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Healthy Soil – Healthy Gardens Travel to the Sarah. P. Duke Gardens Finding the Best Tree for Your Yard

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Sarah P. Duke Gardnes

20 Words of Wisdom

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Giving Trees


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Great Gardens

Editor’s Note Finding Garden Inspiration

Q&A

Your Questions Answered

Our Favorite Things Staff Picks

SOil Life

At the Root of All Good

Soil Science

Cooking Up Compost


T h e re a re d e f i n i t e s i g n s o f autumn in the gardens these days: leaves changing colors, asters and goldenrods in full bloom and pumpkins, gourds and bales of hay decorating front porches. We’re coming into the Thanksgiving season, a time to reflect and show gratitude for all we have, including our gardens and the happiness they bring. At Great Gardens and Horticulture magazines, we’re especially thankful for the wealth of knowledge that gardeners share with us and we in turn can share with you. In the fall issue of Great Gardens, we share tips on planting and pruning trees and shrubs, how to select the best tree for your yard and how to cook up compost. We also pass along some great garden advice from the experts on everything from winter interest plants, low rainfall plants, native plant selection, how to start a garden design and much more.   Thanks for being here to read it!

—Meghan Shinn :: Editor

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Q&A

Can I prune trees and shrubs in the fall?

A:

It’s usually not a good idea to prune trees or shrubs in the fall, for a couple of reasons. First, pruning can trigger a flush of new growth. If this occurs in the fall, the new growth may not have time to harden before freezing weather sets in, leading to damage. Secondly, if the tree or shrub in question flowers on “old wood” (in other words, it has already set flower buds that will open next spring or summer), then pruning in the fall would remove them and diminish next year’s flower display. Wait until midwinter, when the plant is dormant, to prune trees and shrubs that will form flower buds on new wood, in the spring. Wait until just after the plant blooms to prune those that set buds on old wood (this includes Hydrangea macrophylla, forsythia and quince).

Q: A:

Do you have any advice for growing lawn under trees?

If you think about the natural habitats of trees and turfgrasses, it only makes sense that these two plants do not mix well. Trees are used to forests, where they cover the ground with a dense shade; most grasses are used to prairies, where they’re exposed to full sun. Lawns in wooded landscapes have to compete with trees for nutrients, room for root growth, exposure to sun and access to water. It’s an environment of competition and lost potential. It’s easier to adapt our own expectations and ideals than to try to force the plants to adapt. In the long run, you’ll have most success with minimal repeat effort by making a garden under your trees, rather than a lawn. You can apply mulch around the tree, but make sure not to mound it up around the tree’s trunk. Add shade-loving plants and shrubs. There may be a little competition, but not nearly as much as that between grasses and trees. If you must have turf under the canopies of your trees, you can try to supplement the needs of both plants. You can use sprinklers on your lawn and use time-release deep-root fertilizers for your trees. When the trees shed their leaves in the

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fall, shred them with a mulching mower and leave them on the lawn, rather than raking them all up. They will feed the soil as they decompose and thereby feed your lawn. Make sure you’re using a shade-tolerant mix of grass seed. You can also prune your trees to help alleviate some shade on your lawns, but be careful and prune them properly to avoid damaging them.

Q: A:

Is there any special care I should follow when planting shrubs in the fall?

If yo u p l a n t t re e s o r shrubs this fall, be sure to keep them watered until the ground freezes (if it does in your area), and continue to keep them watered through next spring and summer. Even “drought-tolerant” plants should be treated to supplemental water in dry times until they are well established in the ground, which usually takes at least a full year. Most new plants require an inch of water each week—on a new shrub with a 20- to 24-inch root ball that amounts to 10 gallons of water.

Q:

I am exploring hardscape options. What is decomposed granite, and its pros and cons?

A:

Within the category of hardscapes there are two main options: permeable and non-permeable materials. The term “permeable” simply means the ability to let water seep into the ground beneath the material. Dcomposed granite (DG) is a permeable hardscape. It is broken-down granitic rock, similar to gravel. DG is environmentally safe and comes in golds, reds and

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Great Gardens


Q&A

grays. There are two main types: loose and stabilized. Loose DG is a great option for mulching garden beds, because it is rich in minerals. It isn’t always a great choice for patios, walkways or garden paths, though, because it can be easily eroded. In areas with heavy rain, it often becomes muddy and messy. If it’s placed near your home’s entrance, loose DG can easily be tracked inside, where it can mark hardwood floors. The second type of DG, stabilized, is more expensive than the loose mixture, but is less vulnerable to erosion. This version is better suited for walkways, garden paths and patios. It, too, can mar hardwood floors, but it can be wiped off shoes on a good welcome mat. You can also mix resin into your DG to keep it from sticking to shoes. This is very costly, but it’s the best strategy for driveways and walkways under heavy foot traffic.

Q:

I grew some perennials in containers this year that are not hardy in my area. What should I do with them over the winter?

A:

Often potted perennials are treated as annuals, tossed out in the winter season with plans to add new ones in the spring. However, they can survive the winter with some preparation and care. Container perennials rated one or two USDA Hardiness Zones colder than your area have a good chance of living throughout the winter outdoors. For plants not hardy to your area, you have a few options. You can keep them in an unheated interior location, like a garage

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or a cold frame, making sure they do not dry out completely. Alternatively, you can identify warm microclimates in your garden and try one of the following techniques: Plant the container in the ground just before the soil freezes, with the rim of the pot right above or at the soil line. Cover heavily with mulch. Or remove the perennial from the container and plant it closely together with other perennials in the soil, also adding heavy mulch. Another riskier option is to tightly group all the potted perennials, pile heavy mulch over the top and hope for the best. The best location will be one that’s sheltered from wind and strong sun. It may seem counterintuitive, but up against a north-facing wall or hedge is a better choice than a south-facing wall or hedge. That’s because the north wall will stay fairly consistent in temperature, while the south wall may warm during the day and cool drastically at night. This swing can harm the plants. It is very important to keep in mind the container you have selected for your perennials. Can it survive freezing temperatures, or will it crack or break? As the soil in the pot freezes, it will expand. A pot that’s not very durable may break under the pressure. Fiberglass and plastic pots are least likely to break. Terra-cotta, ceramic and concrete pots may survive the winter; the thicker their walls, the better their chances. •

Got questions? Email us at edit@hortmag.com

Great Gardens


soillife

At the Root of All Good

Peter Garnham embarks on an examination of soil and its importance to plant health “It is not enough to be well intentioned, we need to become well informed.”—Bill Mollison Fact: If we do not actively care for the life in our soils, we cannot get truly healthy plants. Compost, of unknown quality, is not good enough. Amendments added to untested soil may do more harm than good. If we want healthy and highly nutritious vegetables and fruit, we have to get serious about providing an environment in the soil that nurtures the millions of tiny critters that live there. It is natural for us, as gardeners, to focus on the aboveground appearance of our plants. If a plant grows well and looks good, we assume that all is well. But if we analyze the leaves and closely study the roots, we may find that the plant’s health and nutritional value are seriously deficient. This can be done at home with a Brix meter, a small hand-held device also known as a refrac-

tometer. They start at around $120, a great investment. The Brix reading is a measure of total sugars, minerals and other dissolved nutrients in a liquid. To quote ag-usa.net, “Crops with higher refractive index will have a higher sugar content, higher protein content, higher mineral content and a greater specific gravity or density. This adds up to a sweeter tasting, more mineral-nutritious [food] with lower nitrates and water content and better storage attributes.” Maintaining a Brix reading higher than 12 results in greater insect resistance. High solids content in crops creates a lower freezing point, making them less susceptible to frosts. Brix readings are higher when soil nutrients are in the best balance and are available to plants via microbes. For example, compare a good-looking vegetable from three sources: a supermarket, a farmer’s market and a carefully

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managed home garden or small farm. They may look identical to the naked eye, but the Brix reading of each will reveal the true health of the plant and its nutritional value, and give you a hint about the condition of the soil in which it grew.

diving into soil

The basic mineral content of soil is simple: sand, silt and clay. The plant nutrient mineral content of soils is derived from these basic minerals. Those nutrients may be present in large quantities but can be unavailable to plants because of conditions that are within our control, such as soil pH. Other nutrients come from water, air and the decomposition of plant material (often called organic matter) by soil microbes and insects. Soil types vary tremendously across the country and, indeed, from one field to the next. There is no one-size-fits-all recipe for


improving soil health, but it’s not hard to figure it out. The first step has to be a soil test by a reputable laboratory. I like Logan Labs (loganlabs.com) for its focus on mineral-nutrient content. A tiny deficiency of, say, molybdenum can make a lot of difference to the health and success of cabbage, cauliflower and the legumes. A molybdenum deficiency looks a lot like nitrogen deficiency—restricted growth and pale leaves that eventually wither. Flower formation may be restricted. Without a good soil test, there is no way to identify and deal with this. Understanding and, if necessary, correcting these basic facts of soil composition allows us to move on to the next stage, which is the care and feeding of soil life. Every time we harvest a crop we are removing organic matter (the plant itself ) and the mineral nutrients it contains. Just like with a bank account, you cannot keep making withdrawals without also making periodic deposits. An imbalance of mineral nutrients and soil life results in plants that may survive—or not—but will not thrive. And even if they look healthy, they may not be as good for you as they should be.

life below ground

More and more gardeners and farmers are coming to realize and accept that a complete ecosystem exists in soil, and that life underground needs our care and attention. Conventional agricultural practices are literally killing our soils. If we are to survive as a species this has to change. Artificial fertilizers and pesticides have widespread and dead-

ly consequences on soil life. We can break out of this downward spiral, which I think we must, by studying and understanding the needs of soil-living insects and microorganisms. It is just as easy to nurture the life in the soil as it is to correct mineralnutrient deficiencies. We just have to learn how to do it, and that is what this series of articles will seek to explain. Compost is a large part of the answer, but not all of it. Many gardeners think that compost is compost and that’s that. Not so! Compost is, by definition, “the oxidated decomposition of a mix of organic matter.” Good compost is beneficial, but bad compost can be extremely harmful. If you think of the millions of microscopic critters in your soil as your pets, then compost is pet food. Just as you would not feed your cat or dog putrefying garbage, those pets in the soil need a good-quality diet, too. In coming issues, I will describe ways to make good compost, and how to evaluate compost you may buy. Every one of the many species of insects and microorganisms that live in the soil have a specific role to play. Bacteria, fungi, nematodes (good and “bad”), protozoa, arthropods and others interact with each other, and the rest of their environment, to produce plant nutrients. In future articles, I will introduce each of these species, what they do during their short but important lives, and how we can give them what they need. • Peter Garnham is an organic farmer on Long Island, N.Y. In 2014 he is writing a series of articles for Horticulture focused on soil.

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soillife

Cooking Up Compost Treat your soil’s hardworking organisms to a high-quality meal

It is now that time of year when the best compost piles are made. We have an abundance of green material that is unavailable for many of us at other seasons, and with a little effort we can find the other essential: brown, or dead, material. Later in the year, we can stockpile dead leaves to use next season. I must begin by explaining what compost is, and what it is not. If you think of all the organisms and beneficial insects in the soil as your pets—as you should!— then think of compost as pet food. Compost is not much of a fertilizer until your pets have done their thing with it. Sure, it increases the organic matter in your soil so that it looks and feels good, and it helps to retain moisture. But that is pretty much all it would do without the help of bacteria, fungi and beneficial insects. Those little critters, most of which are invisible except under a microscope, eat compost. They

also eat each other, multiply, excrete and die. The end products of their activities are plant nutrients. There are many books about compost, ranging from excellent to ridiculous. There are dozens of tools, devices, gadgets and bins that are designed to help with the process, some of which are very useful. By all means, read the books and buy the products, if you have the time and resources to do so. However, once you grasp how “compost just happens” it will seem a lot less complicated, so let us prepare a feast for our tiny pets. I will explain later how it all works and what is going on at various times.

making compost

The main ingredient in compost is brown, dead material such as leaves, wood shavings, sawdust or straw. If you want to get technical, that is called carbon. The second ingredient is green, recently living materials, including

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vegetable waste, pesticide-free grass clippings, weeds that have no seeds. That stuff provides nitrogen. The other essentials are moisture and air. Mix natural materials containing carbon and nitrogen together, add water and air, and you will get compost. How long the process takes and the quality of the finished compost are decided by how much of each ingredient you use and how well you combine them. It is not rocket science, and complicated tools and methods are not needed. Making compost is a bit like cooking. It helps to roughly measure the ingredients, but don’t get crazy about it. The microbes will forgive you.

compost containers and site

You can just toss everything in a heap, but it works and looks better if a compost pile is contained in some way. For practical reasons, the pile should be at


least three feet wide and three feet high; four by four is better. Consider that critical mass. A pile smaller than that will not heat up, and the microbes that decompose everything will not go to work in a meaningful way. Use a circle of wire netting with the ends joined, some wood pallets fastened together to form a square, a concrete-block construction, one of the many attractive compost bins (some made from recycled plastics) or a custom-built deluxe design of solid carpentry. There are also rotating compost bins that tumble the ingredients together, which speeds things along. There is a temptation to put the compost heap at the bottom of the yard. The problem with that is inconvenience—every time you want to add something, whether it is salad trimmings or weeds, you have to take a hike. Think about it a bit, and keep it as close as possible to the sources of materials and not too far from a water supply. It absolutely will not smell if you handle it right.

method

Have a hose with a spray head handy, and a garden fork or compost fork. Form the bottom layer with a dry material, such as straw. About eight to twelve inches is good. Then, as if you are making lasagna, add a three- to four-inch layer of green. Spray it lightly with the hose. Repeat the layers until you have used all your material, sprinkling it lightly with water as you go. Then, as a cook would say, combine thoroughly. Stir it and fluff it and turn it over a few times. Introduce the browns and greens to each other as com-

pletely as you can manage. Now—and this is important— cover it with a tarp, a piece of old plastic, even a piece of plywood. Leave it to work for two or three days, checking it daily for warmth. Carefully thrust your hand into the pile, and you should find a surprising amount of heat. This is called the thermophilic stage, and temperatures can reach 90 to 160˚F. A long-stem compost thermometer is the best way to check. The heat is caused by microbial activity, and it’s enough to kill weed seeds and pathogens. It will cool after a few more days, so then you need to stir it up again. Try to bring the center material to the outside and the outer material into the center. As yet undigested materials will contact each other, and the pile will heat up again. Fluff it up to introduce lots of oxygen, and if it seems dry sprinkle it and mix as you go. If it doesn’t heat up much, it is too dry or there isn’t enough green material. It should smell good, a rich, earthy odor. If it smells off, or stinks, it is too wet or there is not enough dry brown material. Overall, it should be as damp as a wrung-out sponge. Add a light sprinkle of water and some lawn clippings, or a few forkfuls of dry straw or wood shavings, as appropriate. Remember to toss it lightly to introduce lots of air. The more often you turn the pile, the faster you will have usable compost. Shredded or chopped materials also break down more quickly. Don’t rush, however. Unfinished compost, in which there is still lots of microbial activity, can be harmful

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to plants. I like to turn it no more than four or five times, then let it rest and slowly cool down. That’s called the mesophilic stage. Don’t use it in your garden for at least a month or two. There are two reasons to cover a compost pile: it prevents rain washing nutrients through and out of the pile, and it helps to retain the warmth that decomposing microbes favor. As it cools, the larger decomposers—worms, beetles and other smaller critters—will arrive to do their valuable work. When you add the final product to your garden soil, your microscopic pets will thank you. And so will your plants. • Peter Garnham is an organic farmer who lives and works on Long Island, N.Y.


For d r a Aw

N E D GAR

CE N E L EXCEL 2 01 4

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Duke Honoring the latest recipient of the Horticulture Magazine Award for Garden Excellence: Sarah P. Duke Gardens

S

by Meghan Shinn

ince 2003, Horticulture has sponsored the Award for Garden Excellence, with which the American Public Gardens Association calls out one public garden for its commitment to excellence in its displays, practices and relationship with visitors. In 2013, Sarah P. Duke Gardens, on the campus of Duke University in Durham, N.C., received the award. “The American Public Garden Association recognizes the long-term commitment that Sarah P. Duke Gardens has made to conservation, collections management, education and display,” says David Price, chair of the award committee. “The gardens have grown and developed with new programs relevant to today’s society while honoring the historic Ellen Biddle Shipman design. The

Ellen Biddle Shipman designed the Terrace Gardens at Sarah P. Duke Gardens, dedicated 75 years ago this year. The botanic garden has since expanded while still preserving its history.


Clockwise from top: The Page-Rollins White Garden showcases white flowers and plants' forms; the DurhamToyama Sister Cities Japanese Pavilion hosts events of Japanese culture; the Terrace Gardens are a mix of formal elements and exuberant players; the Blomquist Pavilion offers visitors a quiet spot to observe native plants and wildlife.

If you go Sarah P. Duke Gardens Duke University 420 Anderson St. Durham NC 27708 919-684-3698 gardens.duke.edu The grounds are open year-round from 8:00 a.m. to dusk. The Doris P. Duke Center is open Monday through Friday 9:00 a.m. to 6:00 p.m.; Saturday 9 to 5; Sunday noon to 5; it is closed on most national holidays. Double-check open hours when planning your trip. Admission is free.

good design and good horticulture make this one of America’s premier gardens.” In the early 1930s, Dr. Frederic M. Hanes, an original faculty member at Duke Medical School, had the idea to create a public garden on some unused land on campus. An avid gardener, he envisioned a showcase for his favorite flower, the iris. With a generous donation from Sarah Duke, the widow of one of the university’s founders, over 100 flowers beds were created and filled with tens of thousands of irises, flowering bulbs and annuals. Unfortunately, flooding soon destroyed the garden, but like all true gardeners Dr. Hanes was not discouraged. He convinced Sarah Duke’s daughter to create a new garden as a memorial to her mother, who had died in 1936. This garden would be made on higher ground and designed by Ellen Biddle Shipman, a key figure in American landscape history. In 1939, Sarah P. Duke Gardens was formally dedicated. In 2014, Duke Gardens will celebrate the 75th anniversary of this dedication. Today, the gardens, which are funded half by Duke University and half by donors, see over 300,000 visitors each year, welcoming them free of charge. “Duke Gardens’ topography provides vistas of incredible natural beauty and outstanding horticultural display that developed organically over the past 75 years,” says Bill LeFevre, the gardens’ Executive Director. “The fact that 55 acres in the

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center of a major research university were set aside for such an awe-inspiring purpose, with free admission for all, is a gift of immeasurable value.”

The Historic Gardens

Five miles of walking paths wind through the varied sections of Duke Gardens. One might start exploring in the Historic Gardens, where it all began. Dr. Hanes’s flooded iris garden is now the South Lawn, while Ellen Biddle Shipman’s designs can still be admired in the Terrace Gardens. A newer addition, the Frances P. Rollins Overlook, offers a great view of the Terrace Gardens. From the overlook, which uses flagstone recycled from the original terraces, one can see all of the levels at once. (Shipman in fact intended them to be viewed like this, from the west.) The Terrace Gardens feature a strong, straight-lined architecture combined with lush planting combinations and punctuated with containers and structural plants—the style for which Shipman was known. Another piece of history can be glimpsed in the Roney Fountain, which sits at the center of the Rose Garden. The fountain was donated in 1901 to what was then Trinity College. It fell into disrepair over the years, where it sat in a shaded spot on Duke University’s East Campus. When Duke Gardens began looking for a water feature for the center of the Rose Garden, Bill LeFevre thought to simply use

Great Gardens


Top left and bottom right: The new Charlotte Brody Discovery Garden demonstrates organic, sustainable food gardening. Top right: Turk's-cap lily in the Wildlife Garden. Bottom left: Bamboo in the Culberson Asiatic Arboretum. Bottom center: Pitcher plants in the Blomquist Garden of Native Plants.

the Roney Fountain. The fountain, restored using its original molds, looks as though it were custom designed for the garden, which features no-spray and heirloom roses mixed with perennials and annuals. Smaller gardens, including the Leubuscher Rock Garden and the Azalea Court, round out this historic area. Meanwhile there’s much to be seen in Duke Gardens’ newer installations.

Garden Expansions

The main building at Duke Gardens is the Doris Duke Center, a hall used for meetings and events, including weddings. Several distinct gardens lie behind the building, including the Page-Rollins White Garden. This space showcases white flowers and foliage with white variegation. The effect is simple and elegant; the beauty and effectiveness of the plants’ basic shapes is made apparent in the absence of competing colors. The White Garden is a popular spot for outdoor weddings and portrait photography, and its magic shines as a backdrop for evening events, with its flowers and leaves coming aglow. The William Louis Culberson Asiatic Arboretum covers 18 acres of Duke Gardens, serving as a showcase for plants from Asia—familiar favorites like peonies and cherry trees as well as lesser-known garden-worthy species. Design elements common in Asian gardens embellish the Culberson Arboretum, further transporting visitors halfway around the world. For those who wish to experience a piece of Japanese culture, there are traditional Japanese Tea Gatherings at the Durham-Toyama Sister Cities Pavilion and Garden. (For dates and registration, see gardens.duke.edu/programs.) Just as the Culberson Arboretum heralds Asian plants, the H.L. Blomquist Garden of Native Plants celebrates the beauty, diversity and importance of regional endemics. Over 900 species are on display here, including rare and endangered species alongside familiar wildflowers. Visitors see the beauty of Southeastern plants here and glean ideas for using them at home to support birds, beneficial insects and other wildlife. As Sarah P. Duke Gardens embarks on its 75th year, Horticulture salutes its beauty and the people who work to make it such a fantastic destination for gardeners. • Meghan Shinn is Horticulture’s editor.


Words Wisdom of

Gardening tips, design tricks and favorite plants from public-garden professionals across the country compiled by Meghan Shinn

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Challenge: Winter Interest by Bobby Mottern, Director of Horticulture Sarah P. Duke Gardens • Durham, N.C. • gardens.duke.edu

Winter doesn’t have to be a drab time of year in the garden. Here are four sure bets for off-season color—we think of them as the “Final Four” here at Duke Gardens. ‘Concolor’ wintersweet (Chimonanthus praecox ‘Concolor’). This is one of the few large shrubs you detect with your nose and not your eyes—when it’s in bloom, that is. Wintersweet sends a delightful fragrance drifting far through the garden on mild winter days. The 12-by-12-foot cultivar ‘Concolor’ has bright lemony-yellow flowers. It prefers full sun and well-drained soils. USDA Zones 6–9.

winter hazel

lilac daphne

stinking hellebore

photos by Jason Holmes

'concolor' wintersweet

Lilac daphne (Daphne genkwa). Most gardeners are familiar with the sweet smell of the evergreen winter daphne (D. odora), but this 3-foot deciduous relative is heralded for its burst of lilac-colored blooms in late February. It prefers moist, well-drained soils and sun to part shade. Zones 5–7. Stinking hellebore (Helleborus foetidus). Hellebores are a must for winter gardens. This species is a distinctive one, with spidery, dark green leaves that contrast with its chartreuse, belllike flowers during the late winter and early spring. Despite its name, there’s nothing offensive about this plant. It thrives in well-drained soils with light shade. Zones 6–8. Winter hazel (Corylopsis sinensis). A witchhazel relative, this deciduous shrub enlivens the garden in February and March with its mildly fragrant yellow flower panicles that dangle like small lanterns. This 10-by-10-foot shrub grows best in well-drained soils in sun to light shade. Zones 6–8.


Challenge: Low Rainfall by Shelagh Fritz, Garden Manager Gardens of Alcatraz • San Francisco, California • alcatrazgardens.org

While not many people can relate to gardening on an island that was once an infamous maximum-security prison, everyone in California has first-hand knowledge of drought and the need to conserve water. The Gardens of Alcatraz are no exception. We primarily rely on winter rainfall and we’re careful to use it wisely. The restoration of the historic gardens began in 2003, long after the island’s residents left in 1963. Key garden areas were reclaimed from escaped ivy and they now boast flower gardens once again. When planning for the preservation of the gardens,

the Garden Conservancy and partners the Golden Gate National Parks Conservancy and the National Park Service knew that it did not make sense to replant gardens that required lots of water. A 12,000-gallon rainwater catchment was designed to run solely on gravity to get the water to the gardens through garden hoses. Choosing plants for the windy west Prisoners' Gardens proved to be the most challenging. We decided on a palette of drought-tolerant plants that give the look and feel of the 1950s-era garden. The plant list includes Mediterranean plants along

with a few California natives that have evolved to grow in these tough conditions. Our best plants are matilija poppy (Romneya coulteri), Cleveland and Mexican bush sages (Salvia clevelandii and S. leucantha), magenta rockrose (Cistus ×pulverulentus ‘Sunset’), Pelargonium ‘Mrs. Langtry’ and island mallow (Lavatera assurgentiflora). Our garden thrives because we took the time to plan and work with what natural resources we have. That has made gardening on Alcatraz very rewarding. I’m sure even the inmate gardeners were pleased with themselves when their garden bloomed.

working with natural resources makes for higher degrees of success

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Recommended Native Plant: Alabama Croton by John T. Manion, Kaul Wildflower Garden Curator Birmingham Botanical Gardens • Birmingham, Ala. • bbgardens.org

spring foliage

early spring flowers

summer foliage and form

photos by F. R. Spicer, Jr.

fall leaf color

Of all the plants native to Alabama, there is one whose praises we frequently sing. This plant is so special that at our last Central South Native Plant Conference, we sent every participant home with one. Alabama croton (Croton alabamensis var. alabamensis) is one of our state’s 26 endemic plants and a member of the Euphorbiaceae, or the spurge family. Some of the reasons we are so enamored with this plant are its versatility, its durability and its beauty—which is subtle in each season but distinct. We grow Alabama croton in sun and shade, moist and dry soils, and it performs well in all these situations once established. The fragrant flowers appear in early spring. In spring, the foliage has on its upper surface a pleasant Granny Smith apple–green cast, and at all times of the year these somewhat leathery leaves have on their underside a silvery sheen, made visible when a breeze stirs them. In autumn, it looks as if someone took a can of neon-orange paint and sprayed it on some of the leaves. Where this plant is happy, it will drop enough seed so that you will always have seedlings to share. This special plant needs no pampering, and because of its many virtues, we will always grow it and distribute it.

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Great Gardens


Maintenance Tip: Staking Peonies by Andrea Luchini, Horticulturist Hildene • Manchester, Vt.• hildene.org

From late May through early June, thousands of visitors from far and wide come to see the peonies at Hildene, the Lincoln family’s 412-acre estate. More than 175 of our herbaceous beauties, mostly heirloom varieties, need staking each spring. In order to keep our gardens looking as pristine as possible, I minimize the appearance of stakes, maximizing the beauty of the flowers. We do have a few mass plantings in border beds, but for the most part each plant is a large clump within a garden bed and must be staked individually. I have turned a tip from a local plant professional into an easy system for getting all those peonies staked efficiently, with an artistic twist! I stake the plants when they have flower buds so that I can easily tell where to string them. For each peony, I insert five stakes equidistant from each other, just on the outside edge of the clump. Then I take a piece of jute twine and tie it to one of the stakes, a few inches below the flower buds. Going counter-clockwise, I pass the twine through the plant going to every other stake and tautly wrapping the twine once around each, until I’m back where I started. When I’m finished there’s a jute star in the middle of the plant. To catch the outer flowers, I bring the twine around the outside of the plant, wrapping it once around each stake to encircle the entire clump. This method supports the flowers in sections rather than as one big mass.

jute-star staking picture and diagram

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Recommended Native Plant: Flowering Currant by Ty Boland, Horticulture Manager The Oregon Garden • Silverton, Ore. • oregongarden.org

WalterSiegmund

wild flowering currant in spring bloom

One of the most beautiful and dramatic native plants we grow in our garden has to be Ribes sanguineum, otherwise known as flowering currant. It’s easy-care nature and jawdropping spring flower display makes it a favorite of both the visitors and horticulturists here at the Oregon Garden. The shrub does great in partial shade but seems to flower best when placed in full sun. It does not require much water once it is established, making it a great addition to drought-

prone gardens. It is winter-hardy in USDA Zones 6 through 8. This shrub responds very well to aggressive structural pruning, which should be done after the flowering period has passed but before next year’s buds are set. (Spring flowers occur on the previous summer’s growth.) June is usually a good time to start pruning. The best way I have found to propagate flowering currant is to simply stick prepped cuttings directly in the ground in a protected area of your garden where flooding or freezing is

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not a concern. Do this around November and they’ll be rooted by April or May. For whatever reason, they do not seem to like to be pampered in propagation flats with bottom heat! There are several cultivars of R. sanguineum, including ‘Pulborough Scarlet’ and ‘King Edward VII,’ that have dark pink to red flowers. Whiteflowering varieties include ‘Spring Snow’ and ‘Tydeman’s White’. Flowering currant is also one of the best early hummingbird attractors you can add to your garden.


Challenge: Grow As a Gardener by Steve LaWarre, Director of Horticulture Frederik Meijer Gardens & Sculpture Park • Grand Rapids, Mich. • meijergardens.org

Often times, we as gardeners struggle with the simplest things. I’ve developed five rules to make any of us a better gardener. 1. Use what you have. We may love that full-sun perennial, but if our gardens are predominantly in the shade, we should look for plants that do well in the shade. You can bend design rules, but you can’t fudge growing conditions. 2. Keep a journal. Record things like where a plant came from, dates that you plant, divide and harvest. Write down the problems you run into and the solutions you find. You’ll be surprised how handy this becomes

year after year. Problems can be avoided or success can be achieved by reading over past notes. 3. Cultivate friends. One of the most rewarding aspects of gardening is the social aspect. Do you have a neighbor that always raves about a plant in your yard? Share a piece. Perennials love to be divided; this recharges and invigorates the plants. Most of my favorite plants have come to me as starts from family, friends and colleagues. I enjoy returning the favor. 4. Mulch. Top-dressing with good mulch improves gardens. It’s scientific fact. Mulch helps regulate

bleeding heart is a beauty—but not for full sun

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swings in moisture and regulates soil temperatures in every season. As mulch breaks down, nutrients become available to your plants and the microbiology of the soil improves. I like to use a composted hardwood bark. 5. Spend time in your garden. Enjoy the space you’ve created. When we spend time in the garden with our hands in the soil and our knees on the ground, something special happens. We connect with our surroundings in a way that can’t happen from the porch or through a window. I’m not sure who said it first, but this familiar adage is true: The best fertilizer is the shadow of the gardener.


Recommended Native Plant: Apache Plume by Janice Tucker, Volunteer Docent Santa Fe Botanical Garden • Santa Fe, N.M. • santafebotanicalgarden.org

blooms and seed heads of Apache plume

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Every year from spring through fall in and around Santa Fe, the Apache plume (Fallugia paradoxa) returns for an encore performance with its “bloom and plume” show, appearing along the roadsides, in open fields and in home gardens. This showy deciduous to semievergreen shrub typically grows between three and five feet tall but can reach a height of eight feet. The stems have wheat-colored shredded bark. Gracefully arched new stems, growing directly from the roots, surround the older, upright central stems. The small, grayish, downy leaves curve slightly downward. The true beauty of Apache plume lies in its two-inch, yellow-centered, rose-like white flowers followed by silky-plumed seed heads, which cover the branches for several months, giving the whole plant a soft mauve tint. The blooms appear in the spring and sometimes again in the fall, rewarding us with an extended season of visual beauty. The shrub often shows off both its brilliant flowers and feathery plumes at the same time. A member of the rose family, the Apache plume is native to New Mexico, south-central Colorado, southern Utah and Arizona, with a natural habitat of arroyos, dry rocky slopes and woodlands at elevations of 3,000 to 8,000 feet. It is an ideal plant for xeric gardens; because it truly prefers dry conditions, supplemental watering is usually not necessary. It likes full sun and will take temperatures as low as –30˚F. The flowers attract bees and butterflies, and the shrub provides shelter for small wildlife. Birds are attracted to the seeds. This lovely plant lives in the Santa Fe Botanical Garden at Museum Hill and can be enjoyed from May through October there, or wherever it grows naturally.


Recommended Native Plant: Maples from Minnesota by Peter Moe, Operations Manager Minnesota Landscape Arboretum • Chaska, Minn. • arboretum.umn.edu

Experienced gardeners in Minnesota know the importance of selecting plants that will tolerate very cold winter temperatures and shine in a shorter growing season. Red maple (Acer rubrum) is native from Florida to southern Canada, but many of its commercial cultivars will be injured during a real upper-Midwest winter, when temperatures can reach -30°F. Varieties selected in areas to our south do not have time to develop their characteristic fall color here before short days and freezing temperatures have ended the growing season. In response to the need for cold hardy, well-adapted maples, the Minnesota Landscape Arboretum has released three cultivars that thrive in the upper Midwest. Acer rubrum ‘Northwood’ was selected near the small northern Minnesota town of Floodwood by the first Director of the Minnesota Landscape Arboretum, Dr. Leon Snyder. ‘Northwood’ red maple has excellent form and bright orange fall color. ‘Autumn Spire’ was selected from a group of seedlings grown at the Minnesota Landscape Arboretum from seed collected in north-central Minnesota, near Grand Rapids. It has a narrow columnar form and it colors early in the fall, with leaves turning bright red. Lastly, by crossing ‘Autumn Spire’ with ‘Beebe’, a cut-leaf silver maple, we created ‘Firefall’ Freeman maple (Acer ×freemanii ‘Firefall’). It’s a male selection that produces no messy seed. Brilliant early fall color and strong branch angles distinguishes ‘Firefall’ from other Freeman maples, such as ‘Autumn Blaze’. You can see this tree and several other maple varieties on the grounds of the Minnesota Landscape Arboretum, where you’ll find over 1,100 acres of display gardens and collections.

'firefall'

David L. Hansen

'autumn spire'

David L. Hansen

'northwood'

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Challenge: Starting a Design by Lea Anne Moran, Garden Manager Hill-Stead Museum • Farmington, Conn. • hillstead.org

evergreen hedges make the backdrop of hill-stead's sunken garden

The best place to start when making a new garden is with the structure, or bones, of the garden. Landscape architect Beatrix Farrand was a master at using hedges to frame a garden, and she used them to create a backdrop for her masterful plantings in Hill-Stead’s historic Sunken Garden (circa 1920). A hedge can be formal or left to grow naturally for a more informal look. Choose an evergreen hedge to create a privacy screen, to shield an area from wind or sun or to accentuate the plants within the garden. Use these living fences to create lines that draw the eye to areas in the garden you wish to highlight or to direct visitors to another area in your garden. Hedges can create a sense of mystery or intrigue in the garden, too, by hiding certain parts from view until the visitor is upon them. A tall hedge with a narrow opening might serve to beckon the curious visitor into another room in your garden, where you can place a special planting or garden sculpture to add to the sense of discovery. Use a short hedge as a border or to lead the way along a path, to encircle or divide a garden, giving it a formal and orderly appearance. The bones of the garden will give the garden presence no matter what the season. •

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Giving

Trees How to choose the tree that will most

benefit your garden’s design and its wildlife

P

©J. Frank Schmidt & Son Co.

by Jocelyn H. Chilvers and Debbie Roberts

Cherokee Brave ('Comco No. 1') is a native dogwood selected for its vigor, disease resistance and beautiful red-bracted flowers. Its summer fruit attracts birds.

erennials may be considered the queens of the landscape, but trees are most certainly the kings. No other plant does more to moderate our climate and set the scale of our outdoor spaces. Trees are dynamic, colorful and textural sculptures that control our views, serve as focal points and unify our neighborhoods and cities. Sited properly, they can safeguard the house from harsh winds, provide cooling shade in the summer and allow the sun’s heat to warm the home in the winter. They also absorb noise and purify the air we breathe. Trees play a vital role in garden design. They provide the structure and framework of a garden. Trees can be used to provide privacy, soften the angles of a house or accentuate a view. Trees also have a calming and cooling effect on the garden. Whether it’s a hammock strung between two oak trees or a few Adirondack chairs arranged under the canopy of a maple, we live our lives in the garden among our trees. So, too, do an array of birds and small mammals. Whether they’re hiding in masses of foliage, resting in outer branches or nesting in the crooks and cavities of the trunk, local birds and small mammals turn trees into veritable apartment buildings. Trees should nourish the garden and the larger ecosystem as much as they nourish the gardener. That’s something to consider when selecting a species.

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It is key to ask of any potential garden tree: after the blooms have faded, then what? What does that tree offer to the garden next week, next month or next season? flowering (and more) trees

Ask someone what they want from a garden tree, and flowers will fall high on the list. In Connecticut, where Debbie lives, the vast majority of gardens have either a Bradford pear or a cherry as their spring-flowering tree. They all bloom at once, and then the show is over. It is key to ask of any potential garden tree: after the blooms have faded, then what? What does that tree offer to the garden next week, next month or next season? A great alternative to a Bradford pear or a cherry is serviceberry (Amelanchier spp; USDA Zones 3–8), a native tree. Its early-spring flowers feed the bees, and its summer fruit can entice a whole symphony of songbirds to the garden. Serviceberry also plays larval host to several butterfly species, including the red-spotted purple butterfly. Add in its colorful fall foliage and interesting bark, and you have a tree that contributes value to your garden all year long, not just for a few weeks. Other native alternatives include redbud (Cercis canadensis; Zones 4–8) and Cherokee Brave dogwood (Cornus florida ‘Comco No. 1’; Zones 5–9). White fringetree (Chionanthus virginicus; Zones 3–9) offers many of the same benefits as serviceberry—showy spring flowers, bird-attracting summer fruit and nice fall color—and as an added

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©KENPEI: THIS PAGE, TOP RIGHT. ©DEBBIE ROBERTS: THIS PAGE, TOP LEFT; OPPOSITE PAGE, TOP. ©JOCELYN H. CHILVERS: OPPOSITE PAGE, BOTTOM.


Clockwise from top left opposite page: 'Candymint' crab has spring flowers and fall fruit; serviceberry, a multiseason native; fringetree, which also has berries and fall hue; 'Superba' Hawthorne's main attribute is its bloom; blue spruce.

3 keys to choosing a tree When I'm selecting a tree for a landscape design I focus on these three key criteria:

1 2 3

Cultural compatibility— will it thrive in the site’s soil, sunlight and water availability? Size— will it fit the space and the job for which it’s intended?

Aesthetics— does it have decorative aspects that make it multiseasonal? —JHC

bonus its flowers are fragrant. Its crown tops out at 20 feet tall and wide, making it a good choice for small gardens. It tolerates part shade and clay soil, but it won’t abide by drought.

adding winter interest

The trees mentioned above are all deciduous, dropping their leaves before winter. Such trees can contribute winter interest if they have persistent fruit, a strong branch structure or interesting bark, like London planetree (Platanus ×acerifolia; Zones 4–8), a cross between North American and Asian sycamores. Its bark peels away in large plates to reveal creamy yellow inner skin. This is a yearround feature, but the bark assumes center stage in winter, when it’s not obscured by the tree's foliage or companion plants. Of course, evergreen trees remain most gardeners’ go-to trees for winter color, since they retain their leaves or needles year-round. These plants also provide winter cover for animals. Pinyon pine (Pinus edulis; Zones 5–8) is one evergreen conifer that stands out for its beauty, and it feeds wildlife, too. Native to rocky slopes of the Southwest and West, it easily handles drought, cold and strong sun. Its seeds are edible to humans, but they’re usually devoured by birds and other wildlife.

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©JOCELYN H. CHILVERS: LEFT, TOP LEFT. ©MEGGAR @ THE ENGLISH LANGUAGE WIKIPEDIA: TOP RIGHT. ©KENPEI: BOTTOM RIGHT

Opposite page: This evergreen pinyon pine thrives in a narrow strip adjacent to a hot, sunny parking area. Above: Sycamore bark adds winter interest. Top right: The summer berries of Amelanchier alnifolia. Bottom right: 'Globosa' blue spruce.

Blue spruce (Picea pungens; Zones 2–7), another Southwest native, has earned a place in suburban landscapes because of its nice bluish color, its tolerance for sun and its narrow shape, which allows it to fit into garden spaces. It makes an effective year-round screen. For many homeowners, trees are the biggest investment they will make in plant material. And for many gardeners, the opportunity to plant a tree in their garden is pretty rare. Once you’ve settled on your garden-design objectives, don’t rush out to the nursery and buy whatever happens to be blooming at the time. Take a minute to think about all the important roles trees can play, and choose a species with versatility. • Jocelyn H. Chilvers is a Denver, Col., garden designer who writes on design and plants appropriate for the western U.S. at The Art Garden (jocelynsgarden.blogspot.com). Connecticut-based landscape designer Debbie Roberts writes on native plants, design and more

The value of native trees

What does an ornamental tree offer after its beautiful spring bloom? If it’s a non-native tree, the answer is probably nothing. It’s a one-trick pony that might look great for a few weeks, because many of these lovelies are bred for their interesting flowers, often sacrificing fruit and the later interest that it offers. Many don’t offer much habitat value, either. Locally native flowering trees, on the other hand, which evolved alongside local wildlife, can be a great source of food and shelter for pollinators, songbirds and small mammals. When you choose to plant a native flowering tree in your garden, you provide much, much more than simply a tree. And in return you receive a longer show of interest—from the trees’ fruit or nuts and from the animals that come to enjoy them. To find locally native trees for your garden, visit the USDA Plants Database (plants.usda.gov/checklist.html), where you can search by state, Canadian province or species name. The Lady Bird Johnson Wildflower Center’s Native Plant Database (wildflower.org/plants/) is another very useful interactive tool. Lists of native plant nurseries by state can be found at plantnative.org/national_nursery_dir_main .htm.—DR

at A Garden of Possibilities (gardenofpossibilities.com). Both women contribute to the Garden Designers Roundtable (gdrt.wordpress.com).

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Great Gardens Fall 2015