Healthy, fertile soil is the foundation of every successful garden. Whether you’re growing flowers, vegetables, shrubs or trees, improving your soil will help plants establish more quickly, produce stronger growth and become more resilient to pests, diseases and dry weather.
Healthy soil is far more than just dirt. It is a living ecosystem made up of mineral particles such as clay, chalk and sand, along with water, organic matter and millions of beneficial micro-organisms. In fact, a single teaspoon of healthy soil contains more micro-organisms than there are people on Earth. These tiny organisms, together with worms and other soil-dwelling creatures, break down organic matter into nutrients that plants can absorb while creating spaces for air, water and roots to move freely through the soil.
In this guide, we’ll explore five simple ways to improve your soil, helping you create healthier growing conditions for stronger, happier plants throughout your garden.
Test Your Soil
Many plants including rhododendrons and camellias, hate alkaline soil. These acid loving plants cannot access nutrients in alkaline soil and will grow poorly or die. Other plants like ceanothus and lilacs, prefer alkaline soil. Choose the right plant for your conditions and they will thrive.
Work out if your soil is clay, chalk, sand or loam. Use what you know about the local area and pick up a handful of your damp garden soil and feel it in your fingers. If you can mould it easily its likely to be clay. If it contains white lumps or flints it is likely to be chalky.
Reduce Compaction
Soil becomes compact over time by being trodden on and by the actions of weather, such as drought and heavy rain. Clay soils are the most susceptible. Compact soil is very hard and difficult to dig. It does not drain easily and often forms a hard pan that rain runs off, rather than soaking into. It holds very little air and is often devoid of worms and beneficial creatures. Plants will not root easily into compacted soil, nor be able to access nutrients fully, leading to them starving and dehydrating. Compacted soil needs to be dug over.
For heavy soils, like clay, dig in the autumn and leave clumps exposed to the air for frost to break down. Never dig soil when it is waterlogged or frozen, it is very difficult, demoralising and can make the soil structure worse. For lighter chalky and sandy soils wait until late winter or early spring. As you dig over your soil, mix in plenty of organic matter as you go. Use at least one large bag of compost for every two square metres. Digging is very good exercise, but it generally uses muscles many of us don’t normally notice until we sit down later. It is recommended to do some gentle stretches before and after digging.
Once you have dug over your compacted soil try not to walk on it again. If your border or bed is too wide to reach the middle or back without walking on it, lay a plank on the soil to spread your weight or place permanent stepping stones at intervals. If you follow these guidelines you may never need to dig your soil again except to put in new plants or harvest root vegetables.
Mulch with Organic Matter
Organic matter is the decomposing products of anything that was alive, such as plant prunings, vegetable peelings, shredded leaves, grass clippings and animal manure. It feeds the soil’s micro-organisms, which release nutrients for plants to absorb through their roots. It also acts like a sponge, holding moisture for plants during dry weather, loosens clay soils and helps prevent nutrients being washed out of sandy or chalky soils.
Organic matter is most easily added as compost, well-rotted horse manure or soil improvers. It is best replenished every year, and making your own compost is the most economical way to do this.
Each spring, add a 5cm layer of composted organic matter to the soil surface as a mulch. There is no need to dig it in unless the soil is compacted, as the organisms living in the soil will pull it down naturally.
Digging soil that is not compacted damages its structure and releases carbon dioxide into the air. If you cannot mulch the whole garden every year, apply a 5cm layer to a smaller area and mulch a different section the following year.
Mulching improves soil structure, suppresses weeds, reduces water evaporation and warms the soil slightly in spring. While gravel and stone chippings help retain moisture and suppress weeds, organic mulches also replenish nutrients, making them the better choice.
Only use well-rotted manure from herbivorous animals such as chickens, cows and horses. Bedding from rabbits or hamsters can also be composted if dampened first. Fresh manure can burn plants and may harbour harmful pathogens. Before using horse manure, check it has not come from animals that have eaten grass treated with aminopyralid- or clopyralid-based weedkillers, as these chemicals can persist even after the manure has rotted down.
Rotate Vegetable Crops Each Year
Constantly growing the same crops in the same place can deplete the goodness in the soil and allow pests and diseases to build up in one place. Rotate your crops every year. Mulch the surface, but switch between manure and compost depending on the crop you are planning to grow next. Courgettes, pumpkins and beans, for example are greedy, and like manure added ahead of planting.
Constantly growing the same crops in the same place can deplete the goodness in the soil and allow pests and diseases to build up in one place. Rotate your crops every year. Mulch the surface, but switch between manure and compost depending on the crop you are planning to grow next. Courgettes, pumpkins and beans, for example are greedy, and like manure added ahead of planting.
Too much goodness however, makes carrots and parsnips fork and prone to canker (see image to the left), so they prefer compost. If you manure the soil and grow courgettes one year, follow that with carrots the following year. The roots of peas and beans contain nodules which increase the nitrogen in the soil. Follow them with leafy crops, like salads which will like the extra nitrogen.
Don’t Leave Soil Bare
Bare soil is easily eroded by heavy rain and winds. It also allows nutrients to be washed out and soil becomes compacted. Weeds will quickly move in, increasing your work load. In an empty vegetable bed, grow a cover crop or green manure. They should be chopped down and dug in before they set seed. Alternatively, cover it with a layer of wet cardboard or newspaper and top that with 5 cm of compost or rotted manure. The plant material will decay, improving soil fertility whilst suppressing weeds. Some plants also add to soil health, lupins, peas and nasturtiums for example add nitrogen to soil.
In a flower bed try not to leave big gaps between plants. In spring fill gaps in borders with annuals if you are waiting for newer shrubs and perennials to fill out to their full size.
Continue your Gardening Journey
Need a little extra advice? Visit your local Tates of Sussex Garden Centre today, where our friendly knowledgeable, team will be happy to help you choose the right plants and offer expert guidance.
