Living mulch in March: Brunnera macrophylla for an almost weed-free garden

Rather than spending every spring weekend on your knees weeding, you can make your garden almost weed-free with a smart planting method.

Instead of carrying baskets full of weeds out of the borders, more and more home gardeners are choosing a living carpet of perennials. Properly selected ground-cover plants, planted closely together, take on the work otherwise done with a hoe and by hand - and March is the best time to get started.

Why weeds keep returning even when you weed constantly

A vast store of seeds lies dormant in the soil. Gardeners call this a “seed bank”. Seeds that have accumulated over decades wait there for light, moisture and air before they begin to grow. That is exactly where the problem starts.

If you hoe deeply or leave beds bare for long periods, you bring these seeds up to the surface. They receive light, germinate - and the weeding starts all over again. In a sense, every major disturbance of the soil reopens the seed account.

Permanently bare soil practically invites wild plants in. Every gap will be occupied - either by perennials you choose, or by what you regard as weeds.

In addition, not every unwanted plant behaves in the same way. Annual species such as chickweed or purslane mainly spread through seed. Perennial plants with taproots, including dandelions or cleavers, grow deep down and can regrow from pieces of root.

A different approach for different weeds

Anyone wishing to reduce the workload needs a basic idea of what they are dealing with. In practice, this simple distinction is often enough:

• Annual wild plants: germinate from seed, flower, die back and leave new seeds behind.
• Perennial deep-rooted plants: develop strong roots and regrow from sections of root.
• Woody seedlings: young trees and shrubs that become difficult to remove if left too long.

It is best to cut annual species just above soil level rather than digging deeply. This destroys the plant without bringing fresh seeds up from below.

Perennial deep-rooted weeds require another method: the soil should be damp but not waterlogged. You can then loosen taproots fairly deeply using a weed puller or a narrow spade. The fewer root fragments left in the ground, the less often the plant will return.

Small seedlings of maple, beech or ornamental shrubs can also become a problem. Ignore them and, within a few years, you will have a root problem in the border. Ideally, pull out these young plants in their first year - later, they will need digging out.

Living mulch: how perennials simply crowd out weeds

The traditional response to unwanted growth is bark mulch. It covers the ground and slows many seeds from germinating. However, it needs topping up regularly, uses up some nitrogen as it decomposes and does not suit the look of every garden.

“Living mulch” is a far more interesting option. This means perennial ground-cover plants that spread across the earth like a green, flowering blanket. They shade the soil, deny seedlings the light they need, and use water and nutrients before unwanted plants can get them.

A dense carpet of perennials allows hardly any light to reach the soil - seedlings simply do not stand a chance.

These plants offer several advantages:

• They keep the soil cool and moist.
• They protect against surface capping and erosion during heavy rain.
• They provide insects with pollen, nectar and shelter.
• Over time, they save considerable effort because very little hoeing is needed.

Brunnera macrophylla - a star among spring ground-cover plants

Among professionals, Siberian bugloss (Brunnera macrophylla) is considered a real workhorse for shady and partially shaded areas. This variety forms dense clumps, spreads readily and makes a strong floral display in spring.

Typical characteristics of this perennial:

Characteristic	Brunnera macrophylla
Position	Partial shade to shade, humus-rich soil
Flowering period	Roughly mid-March to mid-May
Flower colour	Bright blue, resembling forget-me-nots
Growth habit	Forms dense carpets and self-seeds readily
Special feature	Varieties with silver-patterned leaves are also available

Especially in shaded borders, beneath shrubs or along the edge of woody planting, this perennial turns dull earth into an airy carpet of flowers. Where you previously had to hoe between individual plants, a quick check is usually enough later on to see whether a persistent intruder has pushed through.

How to plant ground cover in March, step by step

March is ideal because the soil is usually drying out but still fresh. The plants then have a full growing season to establish themselves before the following winter arrives.

1. Prepare the soil
   On a frost-free day, remove existing weeds thoroughly, including their roots. Loosen only the top layer and do not dig deeply, so that no fresh seeds are activated.

2. Work in compost
   Spread a thin layer of mature compost and rake it in shallowly. This supplies nutrients while keeping soil disturbance to a minimum.

3. Keep planting distances small
   Plant ground-cover perennials deliberately closer together than conventional perennials. Depending on the species, a spacing of 20–30 centimetres makes sense. The aim is for the leaves to touch after just one or two years.

4. Water thoroughly
   Water every plant in well after planting. This washes soil into air pockets between the roots and surrounding earth, helping the plants establish.

5. Support the first season
   During the first year, water occasionally, especially in dry spells, and pull out the few wild plants that emerge as early as possible.

March is considered the “starting signal”: plant carefully once, then the perennials increasingly take over your weeding work.

Which perennials create long-lasting dense cover

Brunnera macrophylla is only one example. Suitable ground-cover plants are available for many different garden conditions, and they work just as reliably.

Suitable species for shade and partial shade

• Siberian bugloss: Flowers early and enjoys humus-rich, slightly moist soil.
• Barrenwort (Epimedium): Produces delicate spring flowers and tolerates dry conditions beneath woody plants surprisingly well.
• Barren strawberry: Evergreen, with yellow flowers, and well suited to more difficult spots under trees.

Sunny positions: flowers instead of gravel

In full sun, you need tough species able to cope with heat and drought:

• Thyme and other mat-forming herbs: Fragrant, flowering and attractive to bees; ideal for edges and dry-stone walls.
• Stonecrop species (Sedum): Cope well with poor soil and store water in their leaves.
• Cranesbill varieties: Form loose yet fairly closed carpets and bring plenty of colour to the border.

It is important to plant several specimens of the same species rather than mixing everything together too randomly. A larger block of one perennial creates a calmer effect and covers the soil more effectively than a collection of individual plants.

Tips for keeping a flowering carpet easy to maintain

Living mulch is not entirely maintenance-free either. However, a few straightforward rules will keep the work to a minimum:

• Do not keep disturbing the soil: The less you hoe, the more undisturbed the soil’s “seed bank” remains.
• Keep an eye on the edges: Simply cut back ground-cover plants that become too vigorous with a spade, then give away the excess or plant it elsewhere.
• Consider light conditions: Perennials in shade often grow a little taller and more openly. In heavily shaded areas, combining different species can be worthwhile.
• Feed selectively rather than excessively: In most gardens, a small amount of compost once a year is entirely sufficient.

If you are unsure how a species will behave, try it in a smaller area first. This quickly shows whether its growth habit, height and flowers suit your own garden style.

What terms such as “living mulch” really mean

The term “living mulch” ultimately describes a simple idea: rather than spreading organic material such as bark pieces over the soil, a layer of plants performs the same role - but with far more life and colour.

For the soil, this means that temperatures fluctuate less and soil life can work more consistently, while earthworms and microorganisms enjoy better conditions. Over the years, this has a positive effect on soil structure. Water drains away more effectively, and both waterlogging and extremely dry, dusty soil occur less often.

The risks are limited, provided you do not choose extremely invasive species. Anyone planting ground covers that spread too enthusiastically, such as some forms of ivy or ground elder, will need to intervene more later. Better choices are species that form a closed cover but can still be controlled.

The concept is also interesting when combined with vegetable gardens. Low-growing, foot-tolerant plants can be placed between taller crops to protect the soil. Examples include low thyme varieties around the edge or clover in quiet corners. This creates a system in which food crops and ground-cover plants work together - and the weeding basket becomes much smaller.