No matter how many plants we stuff into our gardens, bare patches of soil inevitably appear here and there. Not only does this look unattractive, it also allows space for weeds to flourish. Ground-cover plants, which form low, spreading carpets, are what’s needed. They are usually planted as an understorey to taller clump-forming companions.
Before you venture to the nursery or garden centre you need to know what conditions you are planting into. Is it sunny and dry? Sunny and moist? Shady and moist? Shady and dry? The plant must be happy where you put it if it is to do its job. The other essential thing to do before planting is to clear the area of any perennial weeds and their roots. If the patch is sizeable, buy several plants of the same species — a single plant won’t be enough to cover the whole area in one or two seasons. Here are some of the best carpeters:
For a bright sunny hot spot and free-draining soil
Snow-in-summer, Cerastium tomentosum, is an easily grown silver-leaved plant, 8cm (3in) tall with an indefinite spread that produces masses of star-shaped white flowers in late spring and summer. I plant it under blue-grey-leaved yuccas, red-hot pokers (Kniphofia caulescens) or the blue Mediterranean fan palm (Chamaerops humilis var. cerifera).
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For milder city gardens the Hottentot fig (Carpobrotus edulis) can be used in a similar way. Its long low stems, 15cm (6in) tall, spread and trail about the place and are covered in grey-green slightly curved succulent leaves. Daisy flowers in yellow and hot magenta cover the plant in warm summers.
The houseleeks (Sempervivum spp) are hardier evergreen vigorous succulents that spread and cover the ground with mounds of flower rosettes.
The New Zealand burr Acaena microphylla ‘Copper Carpet’ is an evergreen creeping perennial that reaches 3cm tall and eventually spreads to 60cm or so. It has bronze leaves with small flowers followed by bright red burrs that appear in late summer.
For shadier, darker areas
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Check out Euonymus fortunei ‘Kewensis’, a spindle-tree cultivar. Tiny evergreen leaves 1cm long with pale veins clothe this prostrate shrub. The whole plant is no more than 10cm tall and spreads and scrambles about. It is invaluable as it will grow in the most difficult, darkest, driest, shadiest places. For sharp contrast I like to interplant it with metallic silver Astelia banksia, which tolerates similar conditions.
Euphorbia amygdaloides var. robbiae is another tough plant for dry shade. Growing to about 60cm tall, it produces its lime-green flowerheads in spring above the dark evergreen rosette of leaves.
Black dragon grass, Ophiopogon planiscapus ‘Nigrescens’, prefers a bit more light and moisture but is happy enough without direct sunshine. It is a classic evergreen black strappy-leaved perennial with small lilac flowers followed by long-lasting black berries. It eventually forms clumps 20cm tall by 30cm wide and spreads by underground rhizomes, but is slow-growing to start with, so plant it in clumps or drifts for best effect. For colour contrast pair it with silver-leaved lungworts such as Pulmonaria longifolia ‘Bertram Anderson’.
Mondo grass, Ophiopogon japonicus, is closely related and of similar size and habit but has glossy dark evergreen foliage, small white flowers and wonderful rich-blue berries. I have planted it en masse under hardy but exotic looking trees and it also looks great with the feathery fronds of ferns (shown below).
Ivy has many uses, and as ground cover Hedera helix ‘Très Coupé’ would be an excellent choice for a shady spot under trees or shrubs. It has tiny three-lobed leaves like a bird’s foot and is tougher than its delicate appearance suggests.
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For ground-cover plants delivered to your door find mail-order stockists through www.rhs.org.uk/rhsplantfinder