How to Choose your Groundcovers

Many perennials and bulbs ‘cover’ the ground effectively and are often included in this plant category, but, for this article, we focus on plants that typically grow close to the soil surface but can range in size from 10 cm to around 30 cm. They differ widely in foliage colour, texture, density, woodiness of stem, succulent or grassy characteristics, and so their effect, both aesthetic and environmental, varies too. And, while we so often choose plants for their attractive flowers - and why not - our focus here is, function; what does this plant need to do? Then match it to a plant’s ability to cope with the sun, wind exposure, soil type, aspect and gradient, drought and wet conditions.  

For example:

• Rocky slopes where lawn maintenance is tricky: Choose plants that need little management, spread quickly, have strong roots that will withstand the pressure of moving water and wind, are evergreen, and long-lived.

• Between pavers: Clumping or non-vigorous species able to cope with the reflective heat off pavers, and perhaps take some light foot traffic.

• As a no-mow lawn: Evergreen, mat-forming, plants that don’t die off from the centre, take foot traffic and trimming.

• Beneath trees: Plants for shade and dry soils if beneath dense, evergreen canopies.

• Between shrubs: Takes some shade, won’t compete too much with the shrub for water and nutrients and is happy to spread across the ground rather than using other plants as a jungle gym.

• To edge a flower bed: Not too vigorous, and won’t clamber into shrubs or smother perennials.

• On seasonally/ periodically wet ground: Choose groundcovers that cope with damp and dry conditions, preferably evergreen to prevent soil erosion, compaction and cracking in the dry season.

• As living mulch: Dense, mat-forming leaf growth, spreads quickly, and is evergreen.

• To prevent soil erosion: Plant with strong roots, grows readily on sloping ground,  has dense, mat-forming foliage and stems that spread quickly, is evergreen, handles high winds and heavy rains.

Their variety and problem-solving versatility provide gardeners with a plant for almost every situation. But take note; while the majority are low-maintenance, they are not no-maintenance. That said correct choice reduces the management required.

Space plants according to their rate of growth and how rapidly you want to cover the soil. Consider water availability (drought conditions and water restrictions) and size of the area which affects your budget. Highly visible beds – entrance, entertainment area - may need fast cover, as will areas prone to erosion, like banks, or expansive newly landscaped beds. That said you could establish large areas gradually to limit water use and plant costs and cover the balance of the ground with thick mulch that is easily removed when you’re ready to plant again. Plus, this organic cover will provide you with crumbly, healthy soils for the new plants. Planting in staggered rows covers ground more rapidly, plus helps to reduce erosion on slopes.

Another cost-saving measure is to use cuttings of succulent groundcovers and plant them close together to ensure rapid cover.  Firm around the stems to provide good soil-root contact. If planting many, water small groups as you go to prevent them drying out. Make use of cuttings only in your regions rain season as they will need regular watering for the first few weeks. High heat also affects cuttings and landscapers tend not to plant them in January and February.

Watering:  It is difficult to find the  balance between too much and too little water during the establishment phase; too much and plants may not establish a deep-spreading root system. Too little, on the other hand, encourages shallow rooting resulting in plants that dry out rapidly and drought-prone. So, how much is enough? Keep a watch on your regions weather report and try to establish plants just before rain is due. They will still require water as you plant out, around 2 - 3 cm of water per plant to moisten the entire root zone for the average plant. Add a thick mulch layer to prevent water evaporation.

Mulch depth: A mulch layer 5 – 8 cm deep is enough to block light and suppress weed germination, and prevent soil-borne diseases spreading onto plants from rain splash. Too thick a layer – over 10 cm – limits or blocks oxygen from getting to plant roots. This anaerobic environment suffocates roots causing root rot. Symptoms can include; yellow foliage, lack of growth, dieback, and small leaves.

Control weeds that will compete for water, nutrients and sunlight. Weeds can also suppress strong growth preventing a dense mat-forming.

Trimming and deadheading:

Pruning, or trimming, help stimulate growth by causing new buds to grow from the base or along the plant stem. Annual trimming slows the development of woody growth and keeps them attractive. Cutting back can induce repeat flowering in some species like Dianthus. Cut off infected foliage immediately.