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FIRST PUBLISHED IN 2024

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DISCLAIMER: While every effort has been made to ensure the accuracy of the information contained in this book, the information in this book is intended by way of general guidance, and does not represent professional advice applicable to the reader’s specific circumstances. In no circumstances will the publisher or the authors accept any legal responsibility of liability for loss or damage (including damage to property and/or personal injury) accidental or otherwise arising from reliance on any of the information contained in this book or from the failure of the reader to properly and accurately follow any guidelines in this book.

Plant data and tolerances will be updated in subsequent editions as more plants are grown and observed in more varied and broader landscapes

Barometer Books www.barometerbooks.com

Barometer Books acknowledges the Traditional Owners of the Country on which we live and work. We pay our respects to all Aboriginal and Torres Strait Islander Elders, past and present.

A catalogue record for this book is available from the National Library of Australia.

ISBN 978-1-7635037-0-0

THE ESSENTIAL GUIDE TO BETTER GARDENS TEENA

EDITED BY Sue Flockhart

PRODUCTION BY Gravity Design SET IN Bernino Sans Narrow Light 8.5/10, Trivia Serif Book and Kelson Printed and bound in China

FOR RICK ECKERSLEY | TC

FOR JOHN AND LIBBY ELLIS | LE

The authors are indebted to the following contributors to Plantology:

our planting design philosophy avoidance of plant prejudice the many factors that contribute to a great garden plantology:

part 1 [plant profiles] and part 2 [plant thesaurus]

plant profiles: introduction

plant profiles: how to use this section

plant profiles: settings and styles

plant profiles: plant lists

plant profiles: cultivation notes

plant profiles: tolerances

plant profiles: plant symbols

plant profiles: species summary

part one: plant profiles

from the authors

Between us we have more than sixty years’ professional experience working with plants in the horticultural and landscaping industries. Plants have been a very big part of both our working and personal lives. Essentially, we are advocates for gardens and for the enriching life experiences they bring. There is great joy experienced when appreciating a garden for its beautiful planting. Our best memories of visiting outstanding gardens are attributable to the clever curation and the quality of the nurturing of plants. When plants are used successfully, they lift the spirit. Plants bring beauty and enrichment to our lives. They provide sanctuary and shade as well as seasonal delight. They are key in their provision of food and habitat to other living creatures including birds,bees and insects. They have a positive impact on our lives and on society. The more plants we use, and the greater the diversity, the healthier our microclimates and environments become.

Knowledge of plants is gleaned from years of observation. Thinking about plants, understanding how they look and perform, and assessing their relative value takes years of study. There is a great deal to know: the stages of a plant’s development, the various ways in which different species can be used, the impact of the seasons, and site conditions. As horticulturists we need to draw on both creative and scientific pools of knowledge.

Our combined efforts and experiences –both as horticulturists practising in the horticultural industry growing plants and in the landscape industry designing gardens – bring different yet complementary perspectives to this book. Each of us has both experimented and refined from our learnings over the years.

There was a great benefit in bringing our two minds together for this project. By pooling our perspectives and experiences we have challenged each other and distilled our thinking. In doing so, we believe that Plantology is a more comprehensive reference work that will be useful to home gardeners, landscape designers and landscape architects, and the nursery production industry.

The information and advice we share with you in this book has been derived from literally hundreds of gardens on different sites. We have many years’ combined experience actively assessing, observing, critiquing, consulting on, commercially growing, and personally gardening in our own different spaces. We have also observed plant performance through changing conditions and increasingly hot summers.

We have discussed and debated the merits and challenges of various plant species, and even ironed out some (though not all!) of our personal prejudices towards certain plants. We have certainly challenged each other in researching and writing this book. Plant selection, the use of plants and their maintenance is a complex and evolving discipline. And one thing is certain: we offer as much of our knowledge as we can, although we do not profess to know it all.

In order for the book to have greater appeal and extended geographic relevance, we invited our industry friends to be a part of Plantology. We are indebted to the extremely talented landscape designers and landscape architects – and their photographers – who offered us photos of their work to help demonstrate the versatility of different plant species and the spectacular results that can be achieved. We would love Plantology to sit on a coffee table, for perusing or bookmarking, as much as we would love the book to become worn and dog-eared over time. It is hoped that this will be an informative and long-lived resource to inspire better plant choices in the making of many beautiful gardens.

We are sure that you will share our delight in a considered and well-planted garden, and we sincerely hope that you find this book as enjoyable and useful as has been our journey in writing it.

Teena Crawford and Lisa Ellis MELBOURNE, 2024

PLANT LISTS

For each of the plants profiled, additional lists of species are included to help refine the thinking about the use of the plant being profiled.

These are suggested lists of other plants that will work alongside and together with the plant featured, or may replace the hero plant outright. Note that the lists feature suggestions and are not definitive. With these possibilities, an overall plant palette can be developed for planning the structure, look and feeling of an individual garden.

Importantly, these lists are suggestions and not definitive, and clever planting can often come about when plants are used in challenging and surprising ways.

Complementary plants Plants that pair beautifully with the plant in profile.

This is a list of species that work well when planted immediately alongside or close to the plant in profile. They are complementary in nature aesthetically, size-wise, and also possess similar traits (for example, tolerance to sun and wind).

Associate plants Plants that have shared attributes with the plant profiled.

These plants might be considered for inclusion in the same garden but probably should not be planted immediately adjacent to the profiled plant, due to any number of reasons. Essentially this list is a great tool for building a larger vision of the plant species palette of a garden or larger garden bed. Associate plants will usually work within the same garden theme or setting. The plants in this list may be complementary in some ways (for example, flower colour) but thrive in different aspect or light levels. Or the plant in an associate list may simply grow too large to plant alongside the plant in profile, so from a horticultural perspective it is not a sustainable pairing. It will be necessary to do further research into any of the species that are unfamiliar to ensure that they will work as desired in the garden.

Species for substitution

Sometimes it is not possible to source a specific plant when a garden is being planted out.

And at other times it’s great to extend the possibilities of what might be planted in a particular spot. We suggest that if you’re thinking of one plant, then you might consider another. It’s our way of trying to shake up thinking around the use of plants.

The species for substitution list needs to be used judiciously. Some plants are included in this list as they share a single or small set of visual characteristics and/ or tolerances with the plant in profile. For example, a plant in the substitution list may have similar coloured flowers but may favour more sun or shade than the plant in profile. Other plants are suggested as they may reach a similar size at maturity, or may tolerate similar conditions, such as waterlogging. These suggestions are not ‘cut and dried’ solutions but are offered to encourage broader thinking about alternative plant species.

Additional research into plants suggested for substitution is strongly recommended to ensure that the best outcomes are achieved.

plant profiles

Part One:

Here the spotlight is shone on specific plants for detailed examination. This section, of more than 180 plants, is a broad mix of plants comprising both native and exotic species. The collection features trees, shrubs, groundcovers, vines, ferns and grasses that are all excellent plants. Some plants are obvious superstars while others are less showy but highly valuable, given their reliable performance and range of tolerances. The profile on each plant shows a depth of knowledge and information based on years of research and working with these plants in the landscape.

In the descriptions of the plants, we give reasons why each one is worthy of attention, and tips to optimise the use, siting and planting for best effect in the garden.

We explain why we might select the form of one plant over another that on the face of it may seem very similar. Woven throughout the plant profiles are interesting facts and some fascinating stories about their history. We also identify each plant’s native habitat as this can be a key indicator for identifying how best to use a species, and its wider application in designed landscapes. The full plant description is helpful because information found on plant labels, or in books, is often too limited in scope, and in relation to the plant’s likes and dislikes. Sometimes the data supplied is specific to one area and not actually correct for a broader range of landscapes.

As part of the profile focus, complementary species are identified that can be paired with each plant for great visual results. We also include similar species that can be substituted, to provide a fuller understanding of how each plant can be used.

Garden themes are suggested for each plant in the “settings and styles”. For example, a dry Mediterranean garden, a formal garden, or native Australian garden. This selection of styles and garden settings may help the gardener or designer use a plant in a surprising way, to create a different outcome. The overall list of styles is broad, but not all-inclusive. It’s also worth noting that some outstanding gardens feature plants used in unexpected ways.

Agastache ‘Blue Boa’ | GIANT HYSSOP

Agastache ‘Blue Boa’ is a flamboyant plant grown for its striking violet-blue flowers and its vivid green aromatic foliage. It can be a real showstopper in the garden. This plant grows almost like a sub-shrub, with aromatic leaves that are reminiscent of liquorice or even citrus oil when crushed. The dense foliage provides the perfect backdrop to the showy flowers, which bring bees and butterflies to the garden.

Interestingly Agastache was not grown widely as a garden plant until the 1990s. Since then, the genus has earned huge popularity. Many cultivars have been developed by plant breeders with varying degrees of hardiness, flowering capacity, foliage, and form. These traits of the new cultivars can be attributed to the species used in the breeding process. Importantly, while the parentage of this hybrid is essentially unknown, Agastache ‘Blue Boa’ is one of the best.

When planted in a sunny aspect of the garden it will reward with repeat flowering for many months. Once established the plant requires relatively little maintenance for outstanding floral display.

The iridescent flowers are otherworldly. While the plant takes on an overall blue-purple hue, the base of the flower is matte burgundy-brown which brings a chameleonic quality to the flower colour. In fact this is responsible for the flower throwing to hues of violet, amethyst and even magenta. This makes it a plant that can be used in blue-themed gardens as well as to accentuate purple and pink. The amount of sunlight and the plants beside it will help shape the perception of the flower colour.

It is also a most worthy plant for inclusion in the edible garden for its pollination qualities, and enjoyment of the flowers and leaves in cooking. In Deborah Madison’s book Vegetable Literacy, she writes about the use of the species Agastache foeniculum in the kitchen. One suggestion is to use the leaves and the flowers as a substitute for aniseeds. Foliage and flowers can be used in jugs of iced-water in summer. Flowers can be used to garnish vegetables (and she suggests pairing the foliage with cooked beetroots, or fresh or poached peaches) and the flowers can also be paired with true fennel. Madison also recommends that Agastache is planted in the productive garden alongside flowering chives. She also points out that this herb should not be confused with hyssop which is used in chartreuse and absinthe.

Agastache ‘Blue Boa’ can be employed in perennial, flower and country gardens.

Those keen on long-flowering and showy perennials will be keen to flaunt Agastache ‘Blue Boa’.

settings & Styles

Bee-attracting garden

Butterfly-attracting garden

Container garden

Country garden

Courtyard garden

Edible garden

Flower garden

Gravel garden

Mediterranean style garden

Perennial garden

Pet-friendly garden

Poolside garden

Rock garden

Rooftop garden

COMPLEMENTARY PLANTS

Agapanthus ‘Guilfoyle’

Anemanthele lessoniana

Aster x frikartii ‘Monch’

Calamagrostis Karl Foerster

Ceratostigma willmottianum

Crithmum maritinum

Echinacea purpurea

Eryngium x zabelii ‘Violetta’

Euphorbia dulcis ‘Chameleon’

Miscanthus Yakushima Dwarf Panicum ‘Blue Steel’

Perovskia atriplicifolia

Phlomis fruticosa

Rosmarinus officinalis

‘Prostratus’

Rosmarinus officinalis

‘Tuscan Blue’

Rudbeckia purpurea

ASSOCIATE PLANTS

Agastache Blue Fortune

Agastache ‘Sweet Lili’

Ceratostigma plumbaginoides

Nepeta ‘Walkers Low’

Salvia nemorosa ‘Caradonna’

Symphytum grandiflorum

‘Hidcote Blue’z

Teucrium marum

SPECIES FOR SUBSTITUTION

Agastache ‘Blue Fortune’

Salvia ‘Celestial Blue’

Salvia microphylla

‘So Cool Violet’

species summary

PLANT TYPE perennial, evergreen (herbaceous in cold climates)

DESCRIPTION

semi-evergreen upright and shrubby perennial with aromatic, mid-green leaves, and violet-blue flower spikes from spring to autumn.

SCIENTIFIC NAME Agastache ‘Blue Boa’

PHONETICS ah-GAH-stah-kee ‘Blue Boa’

COMMON NAME giant hyssop hummingbird mint anise hyssop

PLANT FAMILY Lamiaceae – mint family

DERIVATION

Agastache comes from two Greek words: ‘agan’ meaning very much, and ‘stachys’ meaning ear-of-wheat, referring to the flower spikes

ORIGIN Agastache ‘Blue Boa’ parentage is unknown; Agastache species are native to southwestern USA and northern Mexico.

RELATED TO herbs such as thyme, oregano, lavender, sage and mint are members of the Lamiaceae family

cultivation notes

In extremely cold climates Agastache can be treated as an annual. In cold climates Agastache is a short-lived herbaceous perennial. In temperate climates, such as Melbourne, Agastache ‘Blue Boa’ is a reliable evergreen perennial.

Agastache ‘Blue Boa’ will enjoy being planted at the start of the spring season to establish quickly and maximise growth. It should be positioned in full sun or where it will have at least five hours of full sun exposure. It is adaptable to most soil types if welldrained. The garden bed should be prepared by the incorporation of some organic compost or well-rotted animal manure. Plants should be mulched after watering in.

During the first three months, while establishing, some tip pruning may be required to encourage wellbranched, bushy plants.

When flowering has finished in early winter, plants should be tidied and pruned by half. In cold climates, the pruning should be undertaken in early spring. Plants will respond well to fertilising each year in spring and again in late summer.

Deadheading spent flowers regularly will increase quantity and duration of flowering.

‘Blue Boa’ is generally pest and disease free, except when growing in less favourable conditions, i.e. poorly drained soil or too much shade.

The flowers can also be cut and enjoyed indoors.

DIMENSIONS height 700mm x width 400mm

SPACING 400mm

FLOWERING

SEASON mid-spring to end of autumn

FLOWERS broad, twelve-centimetre-long violet-blue flower spikes are borne on stems above the foliage; the two lipped tubular flowers are borne in whorls

FRUIT none

STEMS/BARK square stems, typical of the Lamiaceae family

GROWTH RATE fast

LIFESPAN 5 -10 years, often shorter particularly in cold climates

NOTABLE additional noteworthy CULTIVARS cultivars include:

‘Blue Fortune’ – paler blue flowers and taller growing ‘Sweet Lili’ – pink and apricot flower spikes and grey-green foliage

tolerances

ASPECT full sun afternoon sun part shade

SOIL well-drained soil preferred adaptable

WATER REQUIREMENTS performs best with adequate soil moisture tolerates periods of dryness

WIND EXPOSURE summer wind coastal winter wind rooftop exposure

FROST light tolerance

POLLUTION moderate tolerance

Brugmansia x candida ‘Grand Marnier’

ANGEL’S TRUMPET

The fast-growing Brugmansia x candida ‘Grand Marnier’ can play the role of either an evergreen shrub or small tree, and is prized for its soft large green leaves and pale flamingo-coloured pendant flowers during the warmer months.

All Brugmansia species are native to South America, and particularly Ecuador. Species within the genus can also be allocated to one of two camps. The first is known as the ‘warm group’, which are found growing naturally in tropical coastal areas. The rest belong to the ‘cool group’, which are native to the Andes Mountain region.

All species from both groups hybridise easily with each other, and hybrids produced can also be hybridised further. This has meant that the varied natural habitats and the hybridisation has resulted in many cultivars with varying flower colours, tolerances, and growth habits.

Brugmansia candida was originally described in 1805 as a naturally occurring species. However, in the 1960s it was determined that Brugmansia x candida was a naturally occurring hybrid of two warm region species: Brugmansia aurea and Brugmansia versicolor . ‘Grand Marnier’ is a variety that has been used in garden cultivation since the 1920s. It has been recognised by the Royal Horticultural Society with the Award of Garden Merit.

The mid-green ovate leaves provide an excellent backdrop to its floral show. Brugmansia x candida ‘Grand Marnier’, when established and laden with peachy-pink scented flowers, can be quite breathtaking.

It is excellent for its long-flowering display with as many as several hundred blooms on one plant at a time. The effect can be spectacular when considering that a single pendant flower can be 300mm in length.

In gardens where fragrance is favoured, this is an excellent option; its intoxicating scent pervades the garden, especially on still warm evenings. The perfume attracts pollinating moths to the flowers.

The inclusion of ‘Grand Marnier’ in different style gardens, including Mediterranean style settings, tropical gardens and flower gardens, can be a triumph. Grow it as a small tree canopy in a courtyard garden, or in a large pot on a balcony. In narrow areas between a house and perimeter fence, it is an easy way to bring flowers and foliage outside windows. Judiciously sited in country gardens, and protected from frosts, it will also provide a memorable show.

The spreading habit of Brugmansia x candida makes it perfect for use as a layering plant. Exposing the trunk and lifting the canopy above other species below can bring greater definition and form. The upside of this is that the large pendant flowers appear even more dramatic as they hang down generously from the skirt of the plant into the space underneath.

It is also worth noting that a plant with more yellow-orange flowers sold in Australia is often labelled ‘Grand Marnier’ when in fact this is a different cultivar altogether. The true ‘Grand Marnier’ has peachy-pink flowers; the buds are the palest pink, or even white, and they open to delicious shades of salmon, peach, and soft coral.

Brugmansia x candida ‘Grand Marnier’ is a very useful layering species as well as a spectacular focal point in the garden especially when laden with the generous and beautiful trumpet blooms.