Wildflower Blog

The secret to a resilient garden is to put the right plant in the right place. Simple, isn’t it? But the right place has a few aspects that we will elaborate on in the next few newsletters. Bear with me, it might save you thousands of Rands in the near future. The most obvious place to start is the soil.

We are so used to viewing soil in the landscape as a fairly crude substance we need to stick plants into (exceptions apply) and with enough food and water they will thrive. We even attempt to change the properties of the soil to what we perceive as the ideal multifunctional medium (lots of loam, lots of compost and lots of fertilizer). I think this perception can be traced back to Victorian England when all kinds of weird and wonderful plants started arriving in England from the Colonies. Soils in Britain are apparently not worth much.

Nothing about this perception of soil can be further from the truth. Let us start with the basics.

In terms of nature, we are all accustomed to the concept of an “ecosystem”. In simple terms, an ecosystem is a collection of plants, soils, animals and other non-living entities that interact with each other for every component’s benefit. Such a system is in perpetual flux. Soil is actually the most important ecosystem in our landscape. If this ecosystem does not perform optimally, none of the above-ground ecosystems will. Like any ecosystem, soil can be viewed as an interconnected abiotic (non-living) and biotic (living) system.

To the casual gardener soil can either be classified as sand, loam or clay (or a combination of them). This is not a bad starting point but a very limited view. In the diagram below, the complexity is illustrated but you certainly don’t  have to concern yourselves with it too much.

(Principles of Ecological Landscape Design, Travis Beck, 2013)

Soil also has structure, which simply means that these particles are not evenly distributed but may be aggregated. This allows for more air movement in the soil and also for easier water penetration and movement. It takes a very long time for structure to develop. In Nature, soil also occurs in certain layers (or horisons) that is actually a snapshot of weathering over the years.

This picture was taken at the Vredefort dome site in the Free State.

A typical soil profile includes the following layers: the top layer which is mostly decomposed plant material, the second is a mixed, fertile layer that reflects the original parent material, or transported material like sand. Below that is decomposed bedrock that only contains minerals present in the original bedrock. Many trees and shrubs anchor their roots in this layer. The last layer is normally fairly solid rock. All these layers contribute to plant health.

The fact that is mostly overlooked in soils is the life that soils supports. It ranges from minute bacteria, fungi, small worms, earthworms and many more. It is the interaction between these living elements in the soil and the plants rooted there that keeps the plants healthy, resilient and well fed.

On the Highveld, it is very obvious in early spring. Plants in the veld that have the advantage of a functioning soil ecosystem start to sprout, grow and produce flowers before a drop of rain has hit the ground. By that time, our gardens already received irrigation twice a week. Ironically, many of our garden plants will not sprout again since they rotted in winter when they received water that they could not use.

What should we as gardeners and landscapers do to minimize the impact we have on the most important ecosystem in our artificial landscape? The short answer is NOTHING. Soil and plants complemented each other for millions of years before Homo sapiens even existed. During construction it is accepted that damage to soil and soil structure is unavoidable. What can be done is to store the topsoil (with least impact) separately. Once the landscape needs to be recreated, place the soil back in the reverse sequence of removal. Then it is important to disturb the soil as little as possible. If you till it that will completely destroy the structure and it will lead to compaction and a demise of the soil organisms.  This is the first and most crucial step to ensure that your landscape could adapt to the local climate with the least amount of additional water and fertilizer.

If you really want to be successful and create a low-maintenance landscape, rules about soil apply:

• ONE SIZE DOES NOT FIT ALL
• PLANTS SUFFOCATE/DEHYDRATE IF PLACED IN THE WRONG SOIL MIX
• ADAPT YOUR PLANTS TO THE SOIL TYPE AND NOT VICE VERSA
• RESPECT SOIL AS A LIVING ENTITY. IF YOU KEEP ON SCRATCHING THE SKIN, EXPECT CONSTANT REMEDIAL ACTIONS. RATHER DEVELOP A NATURAL REPLENISHMENT PROCESS.
• MOST PLANTS ARE KILLED BY KINDNESS

Let us look at each of these applications in more detail.

ONE SIZE DOES NOT FIT ALL

All plants have special soil and feeding requirements. If you want to create diversity in your garden, the soil must also be diverse.

ADAPT YOUR PLANTS TO THE SOIL TYPE AND NOT VICE VERSA

Over millennia, plants have adapted to their environment and one of the environmental adaptions that cannot be manipulated very easily is the soil composition. It is therefore much easier to select you plants based on the soil type and not according to your wish-list. Of course soil can be altered on a small and shallow scale where you can plant your perennials and grasses, but when it comes to shrubs and trees with deep root systems, a plant in the wrong soil type is doomed to failure.

RESPECT SOIL AS A LIVING ENTITY. IF YOU KEEP ON SCRATCHING THE SKIN, EXPECT CONSTANTLY REMEDIAL ACTIONS.

Soil teems with life. Over the millennia, plants have adapted to use these life forms in the soil to provide it with nutrients and protect it from pathogens. This intricate network can easily be disturbed and then soil loses its primary function. That means you will have to water more often and supply nutrients more often. The best thing to do is just to cover the soil in winter with a layer of mulch. In winter, the mulch will provide shelter for many insects (which will also be a source of food for some birds) and keep the soil warmer. In summer, the organisms in the soil will start decomposing the mulch and pull it underground where the nutrients will then be available to the plants.

MOST PLANTS ARE KILLED BY KINDNESS

The natural reaction, when you see a plant that does not look too happy, is to water it. In many instances, the plant looks unhappy because of too much water. Use average rainfall as your guide. In the rainy season, does it rain every week? Then your plants need to be watered once week (unless it rained). Most plants are very resilient and can survive drought more easily than flooding. Too much water causes leaching of minerals and oxygen from the soil, resulting in the death of plants due to a lack of minerals and oxygen. (Obviously this does not apply to wetland plants or plants that prefer a heavy clay soil).

So what is the bottom line? USE YOUR COMMON SENSE AND IF IN DOUBT DON’T!

If you feed your soil and also respect it as a complex system that must not be meddled with, your plants will thrive.

I trust that this approach will leave you with more respect for the intricacies not obvious in your garden but will also give you more free time to enjoy it.