Choosing the right plants for your garden starts from the ground up, and understanding your soil is the key to making gardening easier and more successful.
In this guide, author and ecologist Becky Searle explains how working with your soil type can transform the way your garden grows:
Planting for your soil type
One of the most important aspects of gardening, but one that is frequently overlooked, especially by beginner gardeners, is choosing the right plants for the right places. For example, we know that putting sun-loving plants into deep shade will not produce good results. But how often do you think about planting for your soil type? Plenty of plants will thrive in one type of soil but struggle in another. This can be put down to the individual adaptations plants have for life in different soils. Don’t forget that around half of a plant’s biomass is underground, in the soil.
Most plants we buy from garden centres will tell you they enjoy “moist, well-drained soil”. This is the holy grail of soils and is usually achieved by adding plenty of organic matter and letting soil structure build on its own over a period of several years. Some soils are naturally more moist or more well-drained than others, but the addition of organic matter helps to balance this out. For more on how this works, check out my blog on the power of mulching.
The thing with appropriate planting is that once you understand your soil type, growing becomes easy. I’ve said it before and I’ll say it again, there’s no such thing as green fingers, just those who want to learn and those that don’t.
Understanding your soil type
First things first, to make good choices about the plants you grow, you must first of all understand what kind of soil you have. This is the fun part as it involves going outside and getting your hands dirty.
Start by digging a small hole, a few inches deep and scooping out some soil from the bottom. Hold it in your hands and see how it feels. If your soil feels coarse and grainy and falls apart easily, it’s likely sandy. If it is sticky and smooth between your fingers it’s probably clay. If the particles are fine, but don’t hold together very well, it’s likely silt. Next, have a look at the colour. Is it a dark chocolate brown? If so, this indicates plenty of organic matter. If the soil is pale, pallid or particularly rust coloured, it’s likely lacking in organic matter. Now see if you can squeeze it into a ball. If it won't take shape at all it's likely to be sandy and lacking in organic matter. If you can squeeze it into a shape and it stays in that shape easily and does not crumble when squeezed between thumb and forefinger, it’s probably clay.
The next thing you need to do is test your soil pH. This is slightly fraught as soil pH can vary greatly from inch to inch within your garden. So, it's worth taking a few samples from different locations, to be sure. Most soils will be neutral, at between 6 and 7 on the pH scale. However, if you have soil that is below 6 or above 7, it's worth knowing so that you can plant appropriately. pH can determine the nutrient availability within the soil, and also which plants will thrive.
Choosing the right plants for your soil
Let’s look at some of the different types of soil, and how plants have adapted for life in those soils. This may help you to determine which kinds of plants will do well in the soils that you have.
Sandy soils
Plants that are adapted for sandy soils typically have strong, fibrous root systems and waxy or narrow leaves, like we see in lavender. These adaptations help them to stabilise the soil, and minimise water loss through their leaves, as water is often a limited resource on well-drained, sandy soils. Other plants that are adapted for sandy soils may have a deep central taproot, like carrots. These go prospecting for water and nutrients in the lower levels of the soil, while also anchoring the plant to the ground. They often set up strong relationships with mycorrhizal fungi that assist in finding water and nutrients, acting as a secondary root system.
Clay soils
In heavy clay soils oxygen levels can be low especially in winter when the ground is wet. Plants that cope well in these conditions often have robust root systems capable of tolerating temporary waterlogging. Some develop shallow, wide-spreading roots that sit closer to the surface where oxygen is more available. Others can simply shut down root activity until oxygen is more available. Plants such as Iris have this ability and often thrive in boggy or frequently waterlogged conditions.
Nutrients are abundant in most clay soils, as is water, so the problem presented to plants is spreading their roots out in the dense soil structure. By sticking to the upper layers of the soil where it is less compacted, they can achieve this easily. Plants that do well in clay soils include brassicas, hydrangeas and Japanese anemones, amongst others.
Silt soils
Silt soils are rich in nutrients but often prone to waterlogging and surface crusting. Plants that are adapted for silt soils can often tolerate having “wet feet”. Plants like alder, birch and willow can tolerate some waterlogging in the soil through specific root adaptations that allow them to get oxygen even when the roots are wet, temporarily switch off their root respiration, or grow specialised root structures that help them cope with waterlogging for longer periods. Many plants cannot cope with even a few hours of waterlogging, so it’s important that if your silt soils are prone to waterlogging, you get the right plants for the conditions. Silt soils that are not prone to waterlogging are often light and so, plants produce dense root systems that can anchor them securely and help to stabilise the soil.
Another factor with silt soils is that rapid plant growth can easily occur because of the abundance of nutrients. The problem with growth on these soils tends to be more to do with light and space. Many herbaceous perennials thrive in these kinds of soil.
Silt soils often work well for fast-growing plants as they are rich in nutrients that can support fast growth. Annual vegetables and flowers often thrive in silt soils, and during the summer waterlogging is usually not such a problem.
Calcareous soils
Another type of soil that often presents a challenge is calcareous soils. These are alkaline soils and include chalky or limestone soils. These soils are often thin and dry out quickly. They also lack nutrients and have a high pH. So, plants that are adapted for life on calcareous soils are very efficient with their nutrient uptake or have developed strategies to obtain more nutrients from the soil. Wildflowers are often well adapted to calcareous soils, as are many Mediterranean plants such as olives, pomegranate and fig. Plants on chalky soils often form beneficial relationships with fungi to help them find nutrients. Buddleia is another good example of a plant adapted for life on chalky soils.
Loam soil is one of the few soils where most plants will thrive. This is due to its high organic matter content.
Summary
So, if we want to improve our soils and make them more accommodating, it stands to reason that we should be adding organic matter. Dalefoot Compost will do this for you.
However, we also need to ensure that there are live plants in the ground as much as possible to support soil health and minimise soil disturbance. Regular, large-scale disturbance to the soil, such as turning, rotovating or digging over, releases organic matter from the soils and causes a breakdown of the natural soil structure.
Appropriate planting helps us to maintain the health of our plants and our soils as one, making gardening easier and more enjoyable. We can get around this to some extent by building raised beds, growing in containers and improving the soil, so you needn’t feel trapped into one specific type of plant. But if you want healthy plants that thrive easily and naturally, planting for your soil type is essential.
Click on this link for more info on which Dalefoot Composts products to use - https://www.dalefootcomposts.co.uk/our-products.aspx
Becky
Becky Searle is a garden writer and author of Grow a New Garden; Plan, Design and Transform any Outdoor Space. She trained as an ecologist and specialises in soil health and ecosystem gardening. You can follow Becky online at @Sow_Much_More.