Soil types

Here is a brief outline of the basic soil types – chalk, clay, loam, peaty, sandy and silty. To find out your soil type, take a look at it and feel it. Add some water and try rolling it between your hands. Observe how your soil looks and feels, and whether it’s sticky, gritty, friable, or slimy. This will tell you what type of soil you have.

Heavy soil, like clay, is made up of small particles which bind together easily, making the soil prone to waterlogging. Light soil, like sandy soil, is made up of large particles so is free draining which is generally beneficial, but is prone to leaching nutrients. Your soil can be improved by mixing in organic matter such as manure or homemade compost. It helps bind large particles together, helping retain moisture, but also increases the size of smaller particles, aiding drainage. Adding grit will also help improve the drainage of heavy soils.

If your garden or planting area is big, it may be beneficial to test the soil in different areas, as it can vary across a large site. If possible, create main planting areas where the soil is good, saving poorer conditions for hard landscaping, where soil quality is less important.

Chalky soil
Generally alkaline, stony and free draining, as it often overlays a chalk or limestone bedrock. Minerals such as iron and manganese will quickly leach out of the soil, but this can be remedied to an extent by regularly adding fertiliser.

Clay soil
Warms up slowly in spring and goes hard and cracks when dry. It also drains poorly. Although it’s hard to dig, it’s very high in nutrients. It feels lumpy, slimy and sticky when wet. If you rub it through your fingers you’ll notice it’s made up of very fine particles. It rolls into a ball easily and stays in shape.

Loamy soil
Probably closest to the perfect soil type, as it’s easy to work, is not too free draining or prone to water logging, and is packed with nutrients. Loam is made up of a mixture of clay, sand and silt, which each have differently sized soil particles. This means the soil has an open structure, allowing air through the soil, keeping it healthy. If squeezed, loam holds together but doesn’t stick together like the fine particles of clay. It rolls into a ball easily, but won’t keep its shape as well as clay soil.

Peaty soil
Soils containing lots of peat are not often found in gardens. They are acidic and high in organic matter, but low in nutrients. A peaty soil holds plenty of moisture and can get waterlogged. Peaty soils are dark in colour and feel spongy if squeezed.

Sandy soil
Is free draining, easy to work and warms up quickly in spring. However it dries out rapidly and leaches nutrients when it rains, so it needs plenty of organic matter adding to help retain moisture and feed the plants. It’s gritty to touch as it’s made up of larger particles. A rolled ball of sandy soil will crumble away easily.

Silty soil
Is made from fine particles, so is free draining but also retains moisture. It’s also higher in nutrients than sandy soil. It can get compacted easily. Silty soil is smooth to the touch. It rolls into a ball easily, but won’t keep its shape as well as clay soil.

A bit of context
So what does this mean to you, the budding gardener? Well the key here (and a fundamental key at that) is to make sure you can match your soil with the preferred soil type of the plants you are interested in. A puzzle indeed!
To help in this little game our plant descriptions will always tell you the soil type they are most happy in, for example if the description states ‘well drained soil’ you’ll know now that the plant prefers soils somewhere between sandy or loamy.

If you can’t give the plant its preferred soil then you need to work at improving the soil. Below are a couple of fairly common scenarios of soil and plant incompatibility:

Scenario 1 – agave if you have clay soils
Agaves demand well-drained soil and will be most unhappy sitting in water logged winter soil.

What to do:
– Improve your soil structure to aid drainage by mixing in aggregates such as grit or compost.
– Raise the planting area to aid drainage. This takes your plant above the natural water table.
– Plant out in a pot instead.

Scenario 2 – bamboo if you have sandy soils
Bamboos love to be moist and hate drying out even for short periods. This is important to remember if planting bamboo in pots.

What to do:
– Improve the soil structure by adding large amounts of organic matter, to help retain moisture and clog up the free-draining nature of the soil. This will drastically reduce the amount of watering that is needed and help retain nutrients. Oh how bamboo love nutrients!

So as you can see, it’s not always a matter of buying your favourite plants, and throwing them in your garden. It really is worth a little homework first to make sure your soil type is appropriate and, if not, making it so.