Plan ahead. When you plan a vegetable garden or allotment, the time to get started improving your soil is the autumn before you plant (if not earlier). It takes time to build healthy soil. But you and your plants will be much more satisfied with the results than if you wait until the last minute, just before you want to plant.
Observe the existing vegetation. Does your potential allotment currently support a healthy looking crop of plants? Or if it’s a neglected site, a robust population of weeds? If the existing vegetation is weak, it may be a sign that you will have to work harder at improving the soil so your plants will thrive.
Explore the soil. Take a shovel and dig around your potential garden area and explore the soil. Can you dig down 8 to 12 inches or more without hitting hard layers? Do roots from existing plants penetrate that far? The deeper they can go, the better. But it’s the top 6 to 8 inches of soil where you need to focus your attention on soil improvement. Look for earthworms and other signs of healthy soil life.
What color is your soil? You can tell a lot about soil just by looking at its color:
- Dark soil: In general, the darker the soil the more organic matter it contains. Many garden plants perform better in soils that are high in organic matter.
- Brown-red: This is usually a sign that the soil has adequate air and good drainage.
- Blue-green or gray: This is usually a sign that the soil is continuously wet or saturated, a condition that’s not good for most garden plants.
- Yellow: This is usually a sign that the soil is imperfectly drained.
- Mottling or streaking: This is usually a sign of seasonal or periodic drainage problems.
What’s your soil’s texture? At one extreme, soils can be like porous beach sand. At the other end of the texture spectrum, they can be like sticky modeling clay. Neither extreme is ideal, but you need to know your soil’s texture to know the best ways of helping your plants thrive.
So where to start?
Add organic matter. Whether you are trying to get a heavy clay soil to drain better, or light sandy soil to retain water and nutrients, one of the surest ways of improving your soil is to add organic matter. Spread 2 to 4 inches of compost or well-rotted manure, for example, and work it into the soil after you kill the vegetation. Make additional applications as often as you can. Grass clippings, leaves, organic mulches, peat moss, and topsoil are other good sources of organic matter.
Avoid compaction. You’ve worked hard to make your soil nice and fluffy and hospitable to plants. Don’t ruin it by compacting it. When it’s wet, avoid walking on the soil or working it with hand tools or tillers. Create permanent paths separating wide (3 to 4 feet) planting beds, and only walk in the paths. If you make wider beds, place stepping stones strategically to help you reach areas for weeding or maintenance without walking on the soil.
Continue adding organic matter. Every summer, microbes in the soil literally digest and burn up some of the organic matter in the soil. You need to keep adding more to keep improving your soil. In vegetable gardens, where there is an empty bed that will not be used for some considerable period, consider planting cover crops such as buckwheat, annual rye grass, clover or winter rye. You grow these crops to protect the bare soil after you harvest vegetables, then dig them in as another source of organic matter.
When you have done this, then is the time to worry about what fertilisers you may need.