Plant ground-covering perennials in March for a weed-free flowering carpet

Anyone who spends hours on their knees pulling weeds every spring may not realise they are perpetuating an endless cycle. Rather than laboriously removing every shoot, you can plant an area so permanently that weeds barely get the chance to establish themselves. The key is to use particular ground-covering perennials, planted in March, which gradually turn the garden into a continuous carpet of flowers.

Why weeds keep returning despite all the effort

A vast “seed bank” lies dormant in the soil. Every garden bed contains countless seeds of chickweed, orache, thistles, dandelions and more. They need only three things: light, moisture and a patch of bare soil. Many gardeners provide exactly this without meaning to.

Deep hoeing or digging over a large area brings fresh seeds from lower soil layers up to the surface. It also continually creates bare patches where the next seedlings can take hold. The result is that no sooner has a bed been cleared than it looks overrun again after the next rainfall.

Every patch of exposed soil invites weeds in. Keeping the ground permanently planted closes this gap and drastically cuts the workload.

Garden advisers make a clear distinction between annual and perennial troublesome weeds:

• Annual species such as chickweed or purslane germinate in large numbers on open ground, but die after one season.
• Perennial species such as dandelions or cleavers have vigorous roots or runners, and will regrow from even the smallest remnants.

For annuals, a shallow cut just below ground level with a sharp hoe is often enough. The important thing is not to disturb the soil too deeply, otherwise more seeds will be brought into the light. With perennial species, the only effective approach is to lever out as much of the root as possible, ideally when the soil is slightly damp and therefore softer.

Living mulch: ground cover instead of bare soil

Rather than trying to keep bare soil “tidy” every weekend, many experienced gardeners use another approach: they turn open ground into a living carpet of perennials. The principle resembles a layer of mulch, except that it is alive.

These ground-covering perennials grow low or semi-prostrate, branch freely and spread across the soil like a blanket. They allow very little light to reach the surface, making it difficult for weed seeds to germinate. At the same time, they protect the soil from drying out and from erosion caused by rain.

Living mulch works around the clock: it suppresses weeds, retains moisture and brings colour to the border – all without having to carry bags of bark mulch.

Brunnera macrophylla: a spring star for partially shaded beds

One perennial stands out among popular ground covers: Brunnera macrophylla, often known as Siberian bugloss. It emerges early in the year, produces heart-shaped leaves and carries numerous small, sky-blue flowers in spring.

Garden professionals particularly value three characteristics of this perennial:

• It spreads quickly without becoming invasive.
• It copes well with shade and partial shade.
• It flowers for a long period, often from mid-March through to May.

Between woody plants, at the edge of shrubs or beneath lightly shaded trees, it forms a blue carpet that almost entirely displaces weeds. Many cultivars also have strikingly patterned foliage with silvery veins, giving the bed structure even after flowering has finished.

Why March is the ideal month to begin

In March, once the ground has dried out but is not yet bone-dry, the timing works in the gardener’s favour. The perennials then have a full growing season to establish and knit together before troublesome summer weeds reach their peak.

Ideally, prepare the area as follows:

• Carry out one final thorough weeding, removing roots as completely as possible.
• Loosen the soil only at the surface, to a maximum depth of one hand-width.
• Work in a thin layer of mature compost, without digging it over as you would when turning soil.
• Plant fairly densely, so that the foliage will meet within a reasonable time.

The aim is not to create a finely raked plot, but moderately loose, nutrient-rich soil in which perennials can quickly fill the space without vast quantities of new weed seeds being brought to the surface.

Which perennials work as weed suppressors

Not every perennial is suitable as ground cover. Some grow too tall, others remain too sparse, while others are too delicate. Proven choices are robust species that spread over an area yet remain easy to manage.

Using a mixture of several species is worthwhile: it not only creates more varied displays throughout the year, but also leaves the area more resilient to heat, waterlogging and late frosts.

How to plant a flowering carpet correctly

Anyone beginning in March should not be too sparing with the number of plants. Too few perennials leave the soil open for a long time, which only benefits ground elder. As a broad rule of thumb for low ground covers, use:

• Around 7–9 plants per square metre for moderately vigorous species such as Brunnera.
• 10–12 plants per square metre for very delicate species.
• 5–7 plants per square metre for vigorous perennials, such as certain cranesbills.

Water thoroughly after planting so that air pockets in the soil close and the roots make contact with their surroundings. Keep a watchful eye on the area during the first few weeks: remove any weeds that manage to emerge, including their roots, before they can set seed.

Care taken during the first few months will save countless hours of hoeing in the years ahead.

Care through the year: little effort, great effect

Once the carpet has closed over, the workload drops noticeably. Usually, only a few jobs are needed each year:

• Cut back dried stems in late winter.
• Divide and replant patches that have spread too vigorously every few years.
• Occasionally scatter a thin layer of compost.

If you wish, you can add spring bulbs such as crocuses, snowdrops or small daffodils among the plants. They often grow through the perennial cover without difficulty and provide extra splashes of colour from February, before the perennials’ flowering carpet begins.

What living mulch does for soil and climate

Ground-covering perennials do more than simply hold weeds back. They significantly improve the microclimate within a bed. Shaded soil heats up less intensely in high summer, while water evaporates more slowly. During dry periods in particular, this can make the difference between a bed coping and struggling.

At the same time, continuous plant cover provides a safe refuge for many insects and small organisms. This supports long-term soil fertility, as earthworms and similar creatures thrive much more readily in cool, shaded earth than in bare, parched soil.

Mistakes that hold back a flowering carpet

Several common pitfalls arise when gardeners switch to living mulch:

• Planting too late: Starting only in summer gives weeds a considerable head start.
• Leaving excessive gaps between plants: The perennials then take years to meet, allowing weeds to remain dominant.
• Choosing unsuitable species: Planting shade-loving perennials in sunny, dry beds quickly results in weak growth.
• Digging deeply before planting: This awakens huge numbers of fresh weed seeds.

Perhaps the most common misconception is expecting an entirely maintenance-free area. It cannot be achieved with no work at all, but the effort changes substantially. Instead of pulling creeping plants every weekend, it is enough to remove one or two unwanted shoots with a targeted reach a few times a year.

Practical additions: mulch, edging and combination planting

To strengthen the effect further, you can spread a thin layer of mineral mulch or bark mulch around newly planted perennials during the establishment phase. This provides extra suppression of seedlings until the plants have grown densely together. Later, the living carpet takes over this role by itself.

Neat bed edging made from metal, stone or timber prevents turf from pushing into the perennial planting. A clear boundary is particularly worthwhile along paths or lawns, both visually and in terms of maintenance.

Combinations of low ground covers with taller perennials or small shrubs are also effective. The carpet covers the base, while hydrangeas, roses or ornamental grasses provide vertical accents above it. With considered planting design from March onwards, a formerly laborious, weed-ridden bed can become a low-maintenance, multi-layered perennial area that offers something for almost the entire year – and your knees will stay considerably cleaner in future.