How to Improve Garden Soil

Last Updated on 30/11/2022 by Barney

Your garden plants and vegetable garden will never reach their full potential if gardening on poor soil.

improving garden soil for healthy plants

Improving your soil health should be the number one priority in the gardening calendar. Once you have a soil that is easy to work with and is bursting with soil nutrients it is just a matter of a bit of yearly upkeep.

As a professional gardener I have worked on all types of soil and nothing is more soul destroying than trying to plant 500 bulbs in a heavy clay soil or planting up a border with soil compaction.

The holy grail of soil types is loam. A loam soil is fairly light in texture as the soil particles do not stick firmly together like clay soil. This is good for both drainage and oxygen around the roots of plants. Loam soil still needs yearly improvement however, which we have described below.

So, onto the nitty gritty.

Covered in this article are the popular methods to improve soil quality, perfect for vegetable and plant growth.

  • Improving Clay and Heavy soils
  • Improving Loam soil
  • Improving Sandy soil
  • Working with compacted soil

How to improve clay soil with soil improver

improve clay soil with organic matter

Clay soils are rich in nutrients but lack structure. Choice of planting becomes more limited and, lets face it, clay soils can be ugly and working with it becomes a depressing thought, even if it is to only pop out and plant a few bulbs.

Clay soils become frozen in winter, water logged after heavy rain and dry to a rock in summer. So here are your steps to improve this type of soil.

Step 1.

Spread 7 – 10cm of soil improver or organic matter on top of the area you wish to improve garden soil. Lightly dig this into the soil using a garden fork, or spade.

Don’t be too enthusiastic, you are working the soil not beating seven bells out of it. You will damage the existing soil structure especially if the ground is wet or waterlogged. If you have a particularly heavy soil then horticultural grit (not gravel) can also be added to improve drainage.

Step 2.

After you have worked the soil improver into the soil spread another layer organic matter on the soil surface. Another 5cm – 7cm if you have the space as a top dressing.

A quality soil improver will have organic matter blended in with it. This will help with supplying minerals and nutrients, improve aeration and also attract your biggest friend in soil improvement “worms”

Worms do not favor a compacted clay soil however, after you have completed your soil improvement they will multiply in numbers. Earthworms pull plant debris underground and bless the earth with worm poop aka worm casts. Worm casts are very high in minerals and go along way to providing that perfect soil for plants & shrubs.

A worm can eat 4 x its weight in organic matter in a day and what is leaves behind , the poo, or worm castings if you want to be all posh about it is otherwise known as “black gold”. A blackish, sandy loam packed with nutrients for your plants.

How to improve loam soil.

Step 1.

Add organic matter or well rotted manure to a depth of around 5cm over the soil and lightly fork it into the soil.

Step 2

Top dress (mulch) the worked soil with a further 5cm of conditioner / well rotted manure

Although a loam soil is the best soil structure to have but it does not hold nutrients as they leach out over time with rain. Improving a loam soil is fairly straight forward. Spread an even 5cm layer of soil improver or well rotted manure over the soil to be improved and lightly fork it into the soil. This should be carried out yearly to keep your soil in tip top condition. Healthy soil = healthy plants, fruit and vegetables.

 How to improve sandy soil.

Sandy soils do not hold nutrients or water and are therefore a poor planting medium for many plants if the soil quality is not improved.

The soil particles in a sandy soil do not hold together leading to a very free draining soil that is not able to hold water and essential plant nutrients.

Adding organic matter will greatly improve a sandy soils ability to hold onto moisture and nutrients longer.

Step 1.

To improve a sandy garden soil simply spread 5cm evenly over the area to be improved and dig into the soil to an approx depth of 20cm. Do not be tempted to dig more soil improver into the soil than approx 5cm in any one year.

Carry this out once or twice a year for 3 years and your sandy garden soil will be greatly improved.

See below for recommended conditioners for improving soil structure

Dealing with compacted soil

compacted soils need air and water

Compacted soil can be the result of too much foot traffic, working the garden soil at the wrong time and even over working it.

Over worked soil (tilling) without adding organic matter can cause the soil structure to break down and stick together (compaction). Plant roots need an adequate supply of water and air so having a compacted soil is quite disastrous for healthy plant life.

A compacted soil is easily identified when pools of water sit on the soil surface after rainfall.

If this is observed then it is time for action!

Step 1.

Place a 5cm deep layer of organic matter over the soil surface and lightly turn into the soil.

Step 2.

Top dress with a further 5cm of organic matter and let worms do the rest of the work.

Worms will pull down the organic matter deeper into the garden soil and create tunnels which will in turn be beneficial in the transportation of water and air to plant roots.

Do I need a Soil Test?

soil testing can be beneficial in finding out what nutrients your soil holds

You can perform your own soil pH test with readily available kits however these do not report on the soil structure and levels of nutrients contained within.

If you really want to know what your soil is lacking then a soil test can be performed by a specialist company.

A comprehensive report will be produced by sending soil samples.

Expect to pay around £100 for this service.

What is a Soil Conditioning?

Soil conditioning is the term used in improving soil structure by adding and digging in organic matter in garden beds and plant borders to improve soil health and structure.

A good, healthy soil should have the right balance of air, water, nutrients and soil organisms which promote strong plant roots thus healthy plants.

How long does it take before you get a great workable soil?

If diligent in putting a yearly effort into improving garden soil then around 3 years. But, do not stop rest on your laurels there. For plants to thrive they need a constant supply of nutrients that organic matter, well rotten manure, garden compost provides. After this time continue mulching with soil improver or manure and your soil will improve year after year .

What is organic matter?

In gardening, when the term organic matter is used it is referring to material that was once living and now rotten down.

Examples of organic matter are home made compost, well rotted horse manure, mushroom compost, composted bark, composted leaf mould, green manures.

make your own organic matter

Can I make my own organic matter?

You can easily produce your own organic matter with home composting. (and it’s free)

Composted grass clippings, shredded leaves, kitchen waste, cardboard etc make an excellent conditioner to improve garden soil in garden borders, raised beds and and allotments.

I hope we have helped in your quest on how to improve garden soil. Should all your efforts fail we have written a guide to purchasing soil in bulk here. 

It’s A Wrap From Me

Improving soil quality is not an overnight fix. Once the soil is improved make it a yearly gardening task to add a mulch of organic material before the growing season starts. Doing this yearly will keep the soil healthy and also work as a natural weed suppressant.

Let the worms do the rest.