Growing Ground Covers
Growing ground covers can be important in a range of settings, in a smaller scale in a domestic garden or at a larger scale. But in order to understand why groundcovers are important, which ones to choose, and where to use them, we need to understand what we actually mean when we talk about ground cover plants, and delve deeper into why and where they are used.
What are Ground Cover Plants?
When we talk about ground cover plants we are simply talking about plants that can successfully spread to cover the soil below. These are plants that we use to protect and potentially improve the precious soil ecosystem.
These plants can be low-growing shrubs or subshrubs, vines that sprawl over the ground, or a range of other herbaceous plants, including flowering perennials, forbs, legumes or grasses. In order to find ground cover plants we need to look at the form and growth habit of plants, to determine whether or not they will be effective in covering the soil in a particular setting.
To choose the right ground cover plants, we need to go one step further and think about the other characteristics of those plants too. Ground cover plants, in addition to covering the soil, can potentially deliver a wide range of other benefits.
Why Grow Ground Covers?
To understand why we grow ground cover plants in many permaculture designs, we first need to think about why it is beneficial to keep the majority of bare soil covered, and why in many situations, it is best to use living plants to do so.
Bare soil should be covered because it:
- Protects the soil from erosion.
- Aids in maintaining fertility in the soil by preventing nutrient losses.
- Maintains moisture levels in the soil, reducing water loss through evaporation.
- Keeps the soil cooler in high temperatures.
- Suppresses the growth of weeds/ unwanted vegetation.
When we leave soil bare, it can be vulnerable to erosion and degradation. And it is important to remember that for most plant growth, we rely on the soil below our feet. Soil is a thriving ecosystem that teems with life, and just like other ecosystems, it should be protected. When we leave the soil bare, we leave it vulnerable. Plants that provide good ground cover are like a protective armour over that soil.
Bare soil can also be covered with a mulch of organic matter, and mulches are certainly regularly used in a permaculture context. However, there are benefits that living plants can provide in addition to those that can be provided by an organic mulch.
Mulches that are carefully chosen for a specific situation can still protect the soil in the ways described above. But living plants with living roots in the soil can deliver benefits over and above the things listed above.
Ground cover plants can:
- Sequester carbon through photosynthesis.
- Create closed loop cycles, returning nutrients to the soil and adding to soil organic matter as they are chopped and dropped, as herbaceous plants break down, and as roots decay over time.
- Promote a healthy soil biome for the proliferation of beneficial micro-organisms in the soil.
- Create habitat for a range of ground-dwelling creatures, and potentially provide shelter, habitat or food for a wide range of other wildlife.
They can also potentially:
- Fix nitrogen in cooperation with bacteria. Some of that nitrogen is used by the plant itself, but some can be made available in the soil for following plants, and potentially for other plants growing close by.
- Improve the soil structure – by breaking up compacted soil, for example.
- Flower (and set seed) to attract pollinators and other beneficial wildlife to the space.
- Provide fodder/ grazing/ pasture for livestock on a property.
- Provide an edible yield, or other useful yields for us.
Looking at the properties and benefits of particular ground cover plants can help us understand where they can be used, and which options might be most beneficial in a particular setting.
Where We Use Ground Cover Plants
In order to understand the use of ground cover plants a little more, let’s take a look at some of their common applications. By looking at how and where ground covers are commonly used in permaculture schemes, we can gain inspiration to help us understand how to use them on our own properties.
Ground Covers in Annual Cultivation
Ground cover plants can often be used in annual cultivation, in a vegetable garden for example, or in arable farming, as cover crops or green manures.
Cover crops are used to cover the soil for a specific period, typically after the main crops have been harvested in a garden or on a farm, or when gaps open up in the space due to the growing calender.
They not only cover the soil and provide the benefits listed above, they are also used to increase fertility and/or to manage a range of soil macro and micro-nutrients.
Crops that are chopped and dropped (or sometimes which die back naturally in winter) are known as green manures. Since they can improve soil for subsequent crops in some way.
Green manures are often legumes, which fix nitrogen and ensure the availability of this nutrient in the soil for grows that follow. However, there are also other green manures used for different reasons.
Another type of cover crop is known as a catch crop. Catch crops (often fast-growing cereals) are used to retain and recycle nitrogen within the soil to prevent it from being leached away. The nitrogen fixed in the biomass of these plants is then released back into the soil when they are chopped and dropped or begin to decompose naturally.
I use Vicia faba (broad beans aka fava beans, and field beans) as winter cover crops in various areas. Winter tares, winter rye, and mustard are other green manures I find useful where I live to protect and improve the soil over winter for the crops to be grown in different areas in spring.
Of course, which cover crops/ green manures are most useful will depend on where you live, and what you are growing. So it is a good idea to research different cover crops that might be used in your area at specific times of year, and where you might use them.
In gardens and on farms, ground cover plants (often known as cover crops/ green manures in these settings) can be crucial in not only maintaining soil health but also in ensuring the long-term fertility of the system.
Ground cover plants can also be used in annual cultivation in companion planting, when they may be used as companion plants, and as a kind of ‘living mulch’ – perhaps between rows of the primary crop.
When used at the same time as the main crops in a bed or in a field, these may provide more, as mentioned above, than the benefits that can be derived from a typical organic mulch.
For example, I sometimes grow cut and come again lettuce crops, chickweed, or other shallow-rooted leafy greens as ground cover between brassica crops, which without increasing competition too much allows me to obtain higher yields from the same amount of space.
However, it will be important to think about competition. Living mulches or ground cover companion plants must not, of course, outcompete or be overly competitive with the main crops in the area.
Ground Covers in Perennial Food Production
Ground cover plants are also often used in perennial food production.
In fruit tree guilds and forest gardens/ food forests, for example, ground cover plants are, of course, one of the layers in the tiered planting that makes up such systems.
Creating the ground layer in a food forest is an important stage in creating a functioning ecological system.
For example, in my own forest garden, I have a number of key groundcover plants. Among those that I find the most useful are white clover (nitrogen fixation and wildlife/ pollinator attraction), alpine strawberry (additional edible yield), dead-nettle – Lamium purpureum – (wildlife attraction, edible and other yields), mints (wildlife attraction, pest control) and self-seeding sorrels – Rumex ssp. – (edible yields).
Several common ‘weeds’ are also useful as groundcover plants within my forest garden, including stinging nettles (wonderful for wildlife and with numerous yields), ground elder (edible yields and wildlife attractant), chickweed (edible), and more…
It is important to note that some really useful ground covers (that spread readily to cover the soil) can also spread out of control and become invasive in some areas, so it is important to select plants carefully. What makes these plants beneficial in some settings can also often make them a potential problem in others.
However, by choosing the right options for a perennial food producing scheme, you can help create a healthy system and increase your yields.
Ground cover plants are also especially useful in perennial food producing schemes into which livestock are introduced, (such as a silvo-pasture scheme) and in any pastures for rotational grazing.
By choosing the right mix of native grasses, forbs and legumes, we can ensure that we create a groundcover or pasture that is well suited to and safe for the animals we keep. And we can maintain a healthy sward within the system over time.
Ground Covers to Replace a Mono-Crop Lawn
One other area where it can be useful to think about groundcover plants is where we wish to replace a mono-crop grass lawn with a more biodiverse and eco-friendly form of planting, such as a wildflower meadow, or prairie scheme, for example.
By choosing plants native to our areas, we can create a more natural groundcover, with a light and relatively open area that is far more attractive and useful than a boring mown grass lawn.
We might also choose to create a lawn using plants other than grass – using low-growing plants better suited to the environmental conditions where we live.
A number of herbs, for example, like creeping thyme or chamomile can be used to create a lawn area in your garden. Mosses might be used where conditions are cool, shaded and damp, and low-growing sedums and other succulent plants where it is warm and dry. These are just a few of many possible examples…
Ground Cover Plants for Pathways & Other Garden Areas
It can also be useful to think about how you might use groundcovers with hardy and low growing foliage to serve as pathways that are not particularly high traffic areas through certain parts of your garden.
I myself create pathways of white clover through certain parts of my space, scything these down when required to allow access to deeper parts of planting schemes for harvesting or other jobs.
The reason why it might be a good idea to add living ground cover as pathways is that this is one more way to maximise photosynthesis and carbon sequestration, and bring the other benefits of living plants.
A path made of wood chip, gravel, rocks or stones, for example, will no doubt be useful in some settings. But where possible, why not add more plants to make sure that this is not in some ways ‘wasted space’?
Even if you do have a gravel or paved pathway, you might grow groundcover plants between paving, or along the edges of the pathway to spread out into it over time. Choose the right plants and this can still be a practical as well as an aesthetically pleasing decision.
Ground Cover in Erosion Control and Slope Stabilization
Another area where it can be helpful to think about the use of groundcover plants is in developing schemes for slope stabilization.
To stabilize slope, it can be very important to make sure that the soil is covered, to increase water infiltration, reduce runoff and prevent soil erosion.
Choosing the right plants to revegetate slope, however, is of course very important. It is important to make sure that we choose by deeper rooted plants and those with extensive root systems, and to introduce a good groundcover, frequently a shallower-rooted species, to anchor and protect the top layers of the soil.
Ground cover plant can also often be used in planting up earth-working schemes designed to effectively manage, flow or direct water on a property – used in the base of a vegetative swale, for example.
Choosing Ground Cover Plants
There are of course many factors to consider when it comes to choosing ground cover plants for any particular scheme. But key things to think about to ensure that you make a considered choice are:
- The environment in which the ground cover plants you are considering will thrive. (Consider native plants first as these will often grow best where you live.)
- The form and growth habit of the plant in question. (Is it low and mat-forming, vining, or taller and more upright? Is it perennial or annual, deciduous or evergreen? Etc…)
- How does it spread/ propagate? (Does it spread through roots/ runners, by seed etc.? How quickly will it spread/ grow?)
- How large will it grow/ spread? (How closely should plants be placed for effective ground cover with the plant in question? How quickly will the plants grow?)
- What benefits (other than ground cover) will the plants you are considering provide?
These are just some of the things to think about when choosing groundcover plants to use in your permaculture planting schemes.