Sage Advice

Mind the gap

Callum Halstead

Since coming to Cambo Gardens last summer, I have been working closely with our Head Gardener, Katherine Taylor, to improve the planting in various parts of the garden. Having spent a lot of time looking critically at the existing schemes, I have tried to make sense of what differentiates the successful and welldesigned areas from those that require more work.

Of course, there is more than one way to design a garden, and different areas naturally have their strengths and weaknesses. However, there are a few key attributes that have helped the better designed parts of the garden stand out from the rest. The well designed areas have clearly discernible themes, and the plants complement one another, working harmoniously as an ensemble. In general, they are also more densely planted, and thus look full throughout the season— with at least one or two varieties either flowering, or putting on some other sort of display, at almost any given point throughout the year. In contrast, sparsely planted beds with too much soil on show often look quite underwhelming, and the bare soil tends to act as an open invitation for weeds to invade and gain a foothold— always guaranteed to take the edge off any display.

It is sparse planting that I would like to address this month. As most of us add to our gardens bit by bit over time, rather than designing it all in one go, it’s very easy to end up with empty spaces in borders, where not a lot happens at certain times of the year. So, let’s cast a critical eye over what is going on at ground level, and think about enriching the planting in our borders, filling gaps, and getting more out of the space that we have available.

When planting a border, we should be aiming to create a tapestry of plants that work together to cover most of the soil throughout the growing season. As each month goes by, different plants will take over from one another, each growing taller than the last, creating layers of vegetation. This type of planting is called ‘succession planting’ and, when successfully carried out, it results in displays that have a long season of interest, with the added bonus of being relatively low maintenance. Not only will the beds look full and beautiful, but by covering the soil with plants that you do want, you will be leaving very little room for those that you don’t want. This significantly reduces the amount of weeding that you will have to do, leaving you more time to enjoy the display as its crescendo builds.

As many popular garden perennials will not start to put on much growth until April or May, this leaves plenty of room available to create early season displays, using plants that won’t mind having other things growing over them later in the year. Spring bulbs are a natural choice for filling gaps in the early part of the season. Snowdrops (Galanthus spp.), Crocuses (C. spp.), Scilla (S. spp.), Daffodils (Narcissus spp.), Tulips (Tulipa spp.), and numerous other bulbs can all be planted relatively densely around your other plants, to provide a succession of flowers that will last from Christmas to early summer. When planting Daffodils and Tulips as filler plants, I prefer to select shorter growing varieties so that, when they reach the end of their flowering seasons, their floppy leaves can easily be covered and hidden by the foliage of taller plants.

Anemones are excellent partners for spring bulbs. The many wonderful cultivars of our native Wood Anemone (Anemone nemorosa) will slowly spread to form drifts that will start to flower from mid-March. Anemone ‘Leeds Variety’ is a fine form, with its extra-large, pure white flowers. For a touch of colour, A. ‘Robinsoniana’ has soft, bluish mauve flowers, while the white petals of A. ‘Kentish Pink’ are backed with rich magenta, offering a lovely contrast. If yellow is more your colour, then the closely related Yellow Anemone (A. ranunculoides), also known as Wood Ginger, is an excellent choice. It spreads quickly, but is unlikely to outcompete and dominate its neighbours. We grow all of these varieties and more at Cambo, all mixed in together. The combined effect is just magical.

When spring starts to feel like it might just turn into summer, and my larger perennials finally start to get going, I become less fussed about whether or not my filler plants are particularly showy. Rather than spectacular floral displays, what I really want is good, contrasting foliage that will help to frame and foreground their larger neighbours when it’s their turn to take centre stage. As their neighbours grow taller, the amount of light available for the filler plants will gradually decrease. Consequently, many of the best plants to use in this situation are varieties that don’t mind a bit of shade. A good grass to use is Wood Melick (Melica uniflora f. albida). The popularity of this little plant has soared in recent years, after it appeared in a good number of show gardens at Chelsea a few years ago. Its strappy, vibrant green leaves add a touch of brightness to the shady spots between other plants, and its fishing rod-like panicles of little white flowers will dance elegantly in the lightest breeze.

If you would prefer to cover the ground more completely, another shade-lover that will spread to fill the space between your other plants is the perfectly named Mouse Plant (Arisarum proboscidium). This curious cousin of our native Lords-and-Ladies (Arum maculatum) has bizarre flowers that look exactly like the rear end of a mouse that is swiftly disappearing down a hole. The plant is primarily grown for its low-growing, glossy, arrowhead-shaped leaves, which form an attractive ground cover.

Sticking with glossy-leaved plants, a somewhat different option is Ajuga reptans ‘Caitlin’s Giant’, a form of Bugle. If this plant had a persona, I would imagine it to be a bit of a goth. Its shiny, near-black foliage reflects deep hues of purple and green, and it has a tendency to creep around in shady spaces. The usefulness of its ground-covering abilities is augmented by the fact that it is more or less evergreen— and, if it creeps somewhere that you don’t want it to go, it’s shallow rooted and very easy to remove. An alternative would be the Spotted Dead Nettle (Lamium maculatum). Varieties such as L. ‘Pink Pewter’, with its light pink flowers, or L. ‘White Nancy’, with white, are both superb options. Although not evergreen, the marbled silver and green foliage will provide a lovely backdrop for your other plants for much of the season. If you do decide to try Lamium, please don’t be put off if the plants you buy look pretty terrible in their pots, as if they are trying to climb out. For whatever reason, Lamium is just one of those plants that never seems to look good when potted. Once in the ground, they will doubtless perk up and start forming attractive carpets of beautifully textured leaves.

White flowers always give shadier spots a bit of a lift. The sweetly scented Lily of the Valley (Convallaria majalis) is a timeless classic that is ideally suited to filling empty space, and is particularly useful for under-planting deciduous shrubs. If the area you need to fill is on the larger side, then the little-known but quite wonderful Large-leaved Pachyphragma macrophyllum could be the plant to use. Over time, it will form a carpet of handsome evergreen foliage that takes on purple tones through the winter. In early to mid-spring, it produces frothy heads of pure white flowers. For smaller gardens, another of my favourites, the Three-leaved Cuckoo Flower (Cardamine trifolia), will create a similar effect on a smaller scale.

I can’t write an article about useful plants for filling gaps and not mention Epimediums (E. spp.). It’s fair to say that I obsess somewhat over these plants: I grow in the region of fifty different varieties in my own garden. So, you can be assured that this recommendation comes from the heart. These plants offer such value to the gardener at all times of year. Every garden should have one— or perhaps five! The varieties that I mention here will spread to fill space, but there are many other tremendous varieties that are clump-forming, so will stay more or less where you put them. The first that I would like to share with you is a widely available variety that has really impressed me at Cambo this year. Its name is a bit of a mouthful: Epimedium x perralchicum ‘Frohnleiten’. It’s an old cultivar from Germany that produces an abundance of heart-shaped leaves, each with a very attractive veined pattern of fresh green over bronze. The vibrancy of its foliage, and its sweet little yellow flowers, work wonders in areas of deeper shade. Epimedium epsteinii is a very low-growing species that will form a dense matt of deep green, spiny foliage, making it very useful at the front of a border. Its flowers are held sparsely, but they are a joy to behold: four pure white outer petals contrast with the inner four spurred and claw-like petals, which are blood red in colour. My final recommendation is Epimedium ‘Black Sea’, named for its robust foliage that turns from green to a deep reddish-purple through the winter months. While the leaves are big and bold, the flowers are comparatively dainty, each one looking hand-painted with raspberry-red over buttermilk-yellow.

Epimediums are semi-evergreen, meaning that they will hold on to their leaves through the winter, but a fresh set of new leaves will appear in mid-spring. You can leave the old leaves on the plant, but I find the older foliage can start to look a bit tired, so I often cut everything back to the ground in late February to refresh them completely each year. A benefit of looking after the plant in this way is that it provides an uninterrupted view of the newly emerging leaves— which are usually a lovely red or bronze colour, before gradually turning green —as well as showing off the colourful, spidery flowers that appear at around the same time.

It’s all very well me giving you lists of plants to look out for but, as some of them aren’t widely available, it would be unhelpful not to also tell you where you might hope to find them. Three of my current favourite nurseries are listed below. Happy plant hunting.

Beth Chatto produces a fine selection of excellent garden perennials. Most of the plants on offer are varieties that Beth herself once grew and rated highly, so you know what you are buying is garden-worthy. www.bethchatto.co.uk

Macplants Nursery in East Lothian is a longestablished, family-run business that offers one of the widest selections of herbaceous perennials in Scotland. Their plants are extremely well looked after, and always arrive in top condition. www.macplants.co.uk

Edrom Nursery poses a real threat to my bank balance. Their website is full of unusual plant varieties that are hard to come by elsewhere. They have a number of plant specialisms, including Snowdrops, Hepaticas and Epimediums— all of which I find extremely difficult to resist. www.edrom-nurseries.co.uk

Images: Callum Halstead (Arisarum proboscidium/ Epimedium 'Frohnleiten’)