Ground Cover in a Garden
For most people, the aim of ground cover in a garden is to minimize the number of weeds that seed themselves and grow rapidly, marring the appearance of the planting and competing with cultivated plants for moisture, nutrients and, in some cases, light. In the last 40 years or so, as labour has become more expensive, densely leaved low-growing plants have been widely used to accomplish this aim and the term “ground cover plants” has been applied to them.
They are comparatively cheap to buy, easy to plant and available in many different forms: quick or slow to increase; suitable for sun or shade; thriving in freely draining or moisture retentive soils; appropriate to formal or informal schemes, according to species or cultivar. Ground cover plants can be prostrate conifers, shrubs or herbaceous plants, evergreen or deciduous: something to satisfy every need, taste and planting plan.
Ground cover plants quickly colonize sizeable areas and build up a thick thatch of vegetation that suppresses most weeds. The one exception is woody weeds, but these usually appear singly and are easily removed. The perennial quality of most ground cover plants ensures that, with a minimum of pruning and splitting during the winter months, maintenance during the growing season is negligible. Once they are established, there is no longer any necessity to dig and hoe the areas of the garden that are planted with them. The chances of success are maximized if the ground is cleared of perennial weeds before planting. This can be a time-consuming task but it pays dividends.
The art of ground cover lies in spacing the plants correctly to ensure that the ground is covered quickly but without the plants competing for space or losing their characteristic habits from having to spread too far. The estimated spread of a plant can be used as a guide, taking into consideration the means by which it spreads. Those plants that spread by underground or overground runners are, as a rule, the most vigorous. They can be useful when a large area needs to be covered, but the larger plants, in particular, tend to suffocate and choke everything in sight. Clump forming plants are much more containable and there are a number that self-seed as well. These days, when a plant becomes a pest it is possible to eradicate it by painting it out with a glyphosate-based translocated herbicide that is deactivated as soon as it comes into contact with the ground; this should be used sparingly, over limited areas. However, most plants can be kept at bay by digging them up regularly.
The value of leaves cannot be overemphasized when looking at ground cover plants, the different textures and colours being so closely juxtaposed that they create an intricate tapestry. There are greens in every hue, yellow-flushed plants and white-variegated cultivars that prefer shade (for example, Hosta fortunei ‘Aurea’, Lysimachia nummularia ‘Aurea’ and Lamium maculatum); while silvery, yellow-variegated, purple and glaucous foliage perform best in sunshine (Heuchera ‘Palace Purple’, Stachys byzan-tina, Ruta graveolens). Flowers must be woven into the whole scheme, bringing seasonal interest to the composition (Geranium endressii ‘Wargrave Pink’, Helleborus orientalis, Phlox subulata).
Ground cover plants can be used in great informal drifts, covering large areas of the garden. A suitable scheme for a moist shady position would include hos-tas in variety, pulmonarias, hellebores, bergenias, Solomon’s seal and epimediums; in direct sunlight catmints, pinks, thrifts, snow-in-summer, Jerusalem sage and thymes thrive. A steep bank, where it may be difficult to grow grass, can be successfully clothed in a thick mat of St John’s wort (Hypericum calycinum) which carries bright yellow flowers throughout the summer, or periwinkle (Vinca) that raises starry blue eyes over a dense carpet of green leaves in spring -both require pruning in late winter.
In formal designs, where labour-intensive bedding plants might have been used in the past, it is possible to associate neatly clipped cotton lavenders, coloured leaved sages, blue leaved festuca, ivies and chamomile for a pleasing effect.
