Preparing Your Garden Soil for Planting

A healthy garden soil is essential for healthy plants. If your soil is rich and nutritious there will be little need for fertilisers, and even pesticides.

We have all heard that compost is beneficial for our gardens, although most of us don’t know just how truly remarkable it is. Compost is decomposed organic matter, such as leaves, twigs and grass clippings. When you mix all these items together in a compost heap, they break down into organic matter that can nourish your garden. Good organic garden soil is loose and fluffy and retains air, nutrients and moisture well. If your soil is heavily clayed or over sandy, work compost into your beds to improve the soil structure and neutralise the pH. This will also increase the variety of beneficial soil organisms in the soil such as earthworms.

Topsoil is the upper-most layer of soil and is usually between 5-15cm deep. If your topsoil is high quality, it will be dark in colour and rich in organic matter.  Some topsoils are very poor quality and lack nutrients. Should this be the case in your garden you will need to purchase a good quality topsoil, either in bulk or bags and work it into your beds together with the compost.  You are also able to buy premixed topsoil and compost from your local GCA Garden Centre. In addition, topsoil is extremely useful for building berms, raising beds and fixing poorly levelled lawns, as it does not break down the way compost does.

Soil pH is a measure of the acidity or alkalinity in soils. The correct soil pH is vital for plant growth as it influences the availability of essential nutrients and affects the activity of soil microorganisms (the bacteria that decomposes organic matter will decline in acidic soil). When planting your new garden, it is beneficial to check the soil pH to see whether it is suitable or needs to be adjusted. To measure your soil pH use a soil pH meter or ask your local Garden Centre GCA, if they can assist you. If the pH of your soil is less than 5.6, it may be too acidic for most plants to grow in. To raise the pH you can add compost and dolomitic lime. If your soil pH is higher than 6.4 you will need to acidify your soil. This may be done by adding ammonium sulphate or acid compost.

When getting down to the dirty work of planting, make sure you have mixed your compost and natural garden soil using a 50/50 ratio. The compost in your hole is going to attract microbes to the roots which is essential for releasing plant nutrients to this area. Superphosphate and bone meal are two external sources of phosphate which is essential for good root growth and ensures that new plants get off to a good start. Bone meal is also an extra source of calcium for plant growth, so don’t forget to add the recommended amount to your planting hole for optimal results.

Moving onto your vegetable garden. Here the soil preparation is extremely important for producing a healthy crop. Adding a generous amount of organic matter in the form of compost, manure and mulch to your good quality topsoil is the best way to prepare the soil. Dig this in deeply (800mm) for best results. For raised vegetable beds a good quality potting mix can be used although a 1-part compost to 1-part topsoil ratio will work better for larger beds. For your herb garden and containers, a premixed herb or potting mix is ideal. Should you wish to improve your soil structure and water holding capacity even further you can add coco peat or sphagnum peat to your mix. These are natural, organic soil conditioners that save water, aerate heavy clay soil, bind sandy soils and reduce leaching (loss of nutrients).

So, if you suspect your current garden soil is not doing the best it can for your plants, bring in some new soil or start composting your own and reap the benefits of a ‘grass roots’ approach!

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