Garden Advice

How to Prepare Soil for Planting

Throwing a few seeds on the ground or digging in a plant takes moments. Providing the right environment for those seeds to sprout or that plant to thrive takes a little longer. As with so much in life, preparation is key. If you understand a little about what your garden needs and know how to prepare soil for planting, your chances for success improve dramatically.

All that plants need is a stable ground to support their roots, moisture, food and air. The key to this process is to ensure that those things are freely and easily available.So, whether you’re planting a vertical vegetable garden or planning out your new flowerbeds, soil preparation is essential.

Table of Contents:

Know your soil type

Grab yourself a handful of earth, preferably when it’s a little wet, and squeeze it. Does it clump together and stick, or run through your hands like damp sand? If you’re lucky it clumps a little but can be broken apart. The type of your soil is dictated by the balance of clay, sand and silt particles in it. Needless to say, there are advantages and disadvantages to every type.

  • Clay soil – If your soil clumps together when you do your squeeze test, it has a high proportion of clay particles in it. These tiny, dense particles are good at hanging on to moisture and nutrients, but they can pack together too tightly. Clay soils easily become waterlogged, and when they dry out, they compact, making it hard for air, roots or garden tools to penetrate. Read our guide on how to improve clay soil if you’re finding it difficult to plant in it.
  • Sandy soils – Sandy soils fall apart easily, even when wet. They drain freely, which is great if you have a love of plants that don’t like wet feet, The major problems with sandy, free-draining soils are that they dry out quickly and nutrients can be washed away by the free-flowing water.
  • Silty soils – In size, silt particles fall between sand and clay. Silty soils tend to have a higher natural nutrient content than sandy or clay ones. Some degree of silt is good for plants, but soil with a very high proportion of silt and little else can become close-packed, waterlogged and lacking in air.
  • Loam – If your soil becomes compact under pressure, but then breaks apart easily, you most likely have a loam soil, with a nice balance of sand, silt and clay. Loam soils also have a good amount of humus, that’s decayed organic matter, in them. If you’re lucky enough to have a loamy garden, the work required in soil preparation is greatly reduced.

Test your soil’s pH

Find out if your soil is acidic, alkaline or neutral. On the pH scale, 7 is neutral, anything below is acidic and anything above is alkaline. Most plants will tolerate a range of pH, though the majority prefer soil that’s slightly acidic – between 6 and 7 on the scale.

How to test your soil – You can buy a basic pH testing kit from most garden centres or online. Alternatively, you can send soil samples to a professional laboratory and get a more detailed report, which will cover the pH value, the content of essential minerals and tell you something about how well the soil retains or gives up those nutrients. 

Home testing is adequate for most people, but if you’re starting a garden from scratch or planning to invest in some rare or expensive specimen plants, you might choose to opt for a more detailed analysis. Whether you test at home or send samples to a lab, you’ll need to test more than one area, pH levels can vary more than you might expect, even in quite small gardens.

Soil that’s very acidic, below 5.5 or markedly alkaline, above 7.5 will need correction. You do this by adding aluminium sulfate to lower the pH making the soil more acidic, or adding lime to increase the pH and make the soil more alkaline. Corrections to pH may need to be done over more than one season as it takes a while for things you introduce to be fully incorporated.

You can correct pH to a certain extent, but if your soil is fundamentally quite strongly acidic or alkaline there’s a lot to be said for focusing your garden around plants that will thrive in the conditions you have. It’s always easier to work with nature than to fight against it.

Soil improvement

Once you know what you have, it’s time to set about making it better. Regardless of what type of soil you have in your garden, you can always improve it by adding organic content:

Clay soils – Organic matter works its way between tightly packed clay particles, preventing them from sticking so tightly together. In clay soils, organic materials improve drainage and soil structure and make the garden easier to work in. Here are some extra tips on how to improve clay soil.

Sandy soils – Adding organic matter to sandy soils improves water retention and prevents nutrients from being washed away in heavy rain.

Some common organic materials

Plant materials such as straw, grass clippings or leaves – These should be dug into the garden some months before you plan to plant anything. Most gardeners do this in the late autumn or early winter.

  • Well-rotted manure – Fresh manure can damage plant roots and introduce disease. Well composted manure is another matter. If you’re able to source it, add it to any garden at the rate of around 30-40 pounds per 100 square feet. As with plant materials, manure should be added to the ground some months ahead of planting.
  • Composted sawdust – You can use sawdust to increase the organic content of your soil but it MUST be well-composted first. Breaking down the carbon in sawdust requires nitrogen, so adding fresh sawdust to the soil will ‘steal’ nitrogen that your plants would much prefer to have for themselves.
  • Green manure – Keen gardeners sometimes grow crops just to dig back into the soil. Vetch, various clovers and alfalfa are all popular green manure crops in the UK. They’re generally planted in the spring to be dug back into the ground in the autumn. 
  • Compost – Compost is simply decayed vegetable matter. Every garden benefits from a small area devoted to composting. In a small garden, this could be a compost bin for your kitchen vegetable peelings. In a larger space, you’ll probably want to do more composting, but that’s a subject for another day. To learn more about composting, check out our home composting guide.
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Improving soil by adding organic matter isn’t a once and only thing. As the soil is continually used it will generally benefit from regular treatments to keep it fertile. And, there is such a thing as too much, when you’re adding compost to a soil spread it first. The maximum depth of compost to add to a given area at one time is 4 inches.

Clay soils often benefit from the addition of gypsum – which both adds nutrients and makes the soil easier to work. Clay soils can also benefit from the addition of sand alongside the organic matter. Gypsum should be added at the rate of 3 to 4 pounds per 100 square feet of soil. If you decide to add a sand and organic mix, then 2 inches of sand and 3 of organic matter is a good balance.

Mulch the soil

Digging compost into the soil is one way of increasing the organic content and nutrients in it. Another method is to lay the organic content over the soil, this is known as mulching. Mulching has advantages and disadvantages.

Reasons to try mulching:

  • Digging in organic content needs to be done before planting, mulching can be done at any time of the year;
  • Mulch decomposes naturally over time, releasing minerals in a slow steady flow;
  • Mulch layers suppress weed growth, keep the soil cool and retain water in the earth;
  • If you favour ‘no-dig’ gardening, then mulching is the best way to add organic matter to your soil.

Possible downsides to mulching:

  • Using the wrong materials can release the wrong minerals into the soil or can tie up minerals that your plants need, so make sure you use the right type of mulch;
  • Keeping the soil continually moist has the potential to encourage the development of fungal diseases;
  • Spreading a mulch too thickly can stop air, which plant roots and the beneficial bugs and worm that live in the soil need.

If you decide to build a raised garden bed now or in the future, know that these tips will work for that as well.

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Get some expert help with soil preparation

Getting your garden soil ready for planing isn’t as complex as it might seem at the outset, but if you’re looking for some assistance from professional gardeners with green fingers and strong backs then you always rely on Fantastic Services. Give us a call anytime or use our simple online booking form to set up your first appointment.

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  • Good soil preparation is the key to gardening success.
  • The aim of preparing the soil is to ensure that plants have the water, air and nutrients they need.
  • Before working on your soil, you need to understand it’s basic structure and pH.
  • Add organic matter to improve soil structure and increase the nutritional content.
  • The major methods of adding organic matter are digging in and mulching.

If you’d like to know more about different garden tasks and when to perform them, take a look at our gardening calendar for the UK!

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