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July 10, 2012

Do you know your soil?

Do you know your soil?

Soils is a mixture of clay, sand, limestone and humus

Get to know your soil and you’ll have a flourishing garden in bloom for the summer

The key to a healthy garden and thriving plants is balanced, nutritious ground.

All soils are a mixture of clay, sand, limestone and humus; the ratio varies depending on where you live and what kind of land you live on. Trying to replace the soil you have with a different variety isn’t the answer – it’s expensive, difficult and may contain weed seeds.

Instead, you need to get your hands dirty and find out which of the six soil types your garden has, so you can select your plants accordingly.

Then you can start to improve your ground by digging in plenty of compost and well-rotted manure – around half a wheelbarrow full per square metre. This will help drainage and aeration on heavy soils and conserve essential moisture on lighter ones. You can buy soil improvers at garden centres, but they are expensive. Much better is a ‘steaming pile’ of horse manure delivered, or using your own compost heap.

Chalky
Texture: Very stony and a light brown colour.

Properties: Chalky soils are difficult to work with. They are alkaline, usually with a pH of 7.5 or more. They become very dry in summer and often overlay chalk or limestone, meaning that they block minerals such as iron and manganese stopping them from reaching the plants which causes poor growth and yellowing of leaves.

Planting: Chalky soils can support a wide range of plants, but avoid acid-loving plants such as rhododendrons and camellias. Achillea, Anchusa, chamomile, cornflowers, lilacs, Lisanthus, Madonna Lily’s, paeonies, poppies, Weigela and Myrtus and mock-orange shrubs will grow best.

Improving: Reduce the alkaline content by regularly adding acidic materials such as compost, fertilisers or leaf mould.

Clay
Texture: Very sticky and lumpy when wet; rock-hard when dry.

Properties: Clay soils are made of very fine particles with few air spaces, so they are hard to work with. They often drain badly but if drainage is improved plants grow well as it holds more nutrients than other soils.

Planting: Perhaps surprisingly, the capacity of clay soil can produce the most beautiful flowers. Perennials such as Aster, bergamot and Helen’s flower will bloom, as do Sedums, Solidagos and flowering Quince and Weigela shrubs.

Improving: Dig in lime to break up the soils heavy structure, and add well-rotted organic matter such as compost to improve the drainage and aeration of the soil. When planting you’re planting shrubs dig grit or sharp sand into the bed to improve drainage.

Loamy
Texture: Smooth with a flour-like texture

Properties: Arguably the perfect soil. Loamy soils are a combination of around 40 percent sand, 40 percent silt and 20 percent clay. It has a good structure, drains well while retaining moisture, is full of nutrients and is easy to cultivate. Better still, it warms up quickly in spring and doesn’t dry out in summer.

Planting: If you’re blessed with loamy soil, you can you have just about any plant in your garden. Black Bamboo, Delphinium, Dog’s Tooth Violet, Rubus, Wisteria are all beautiful plants that grow particularly well in this fertile soil.

Improving: As loamy soil is considered to be the ideal soil, it can’t be improved. So you’ve got complete freedom over your planting.

Peaty
Texture: Dark in colour and spongy to the touch.

Properties: Peaty soil holds more organic material than other types because its acidity slows down the process of decomposition. But it also contains fewer nutrients, and is prone to retaining too much water.

Planting: Many of the prettiest garden shrubs thrive in acidic, peaty soil. Azaleas, camellias, heather, magnolia, Crinodendron, Pernettias, Rhododendron and witch hazel are all well matched and will bloom brilliantly.

Improving: If you improve the drainage by digging sand into the bed and add fertiliser it can be an excellent soil.

Sandy
Texture: Feels crumbly and gritty to the touch.

Properties: Formed from weathered rocks like limestone, quartz, granite and shale, sandy soil dries out fast, warms up quickly in spring and is easy to cultivate. However, it may lack nutrients, particularly in wet weather when they are easily washed through.

Planting: Sandy soil is very sharp draining, meaning it does a poor job of holding moisture, so plants that grow in it must have a tolerance to drought. Adam’s needle, Blanket flower, broom, Hibiscus Sun Rose, tulips, tree mallow, Yarrow and shrubs will all grow well.

Improving: Mix in a layer of loam to improve the soil structure, line the base of a planting hole with newspaper to lessen water loss and add lime to correct the soil’s acidity level.

Silty
Texture: Smooth and soapy.

Properties: Silty soil is very good earth if well managed. One of the most fertile soils, it retains moisture, is rich in nutrients and has good drainage. When dry it has a smooth texture and looks like dark sand. Its weak structure means it is easily compacted and simple to work with.

Planting: Silty soil means you’ll be treated to colourful, blossoming flowers. Mahonia shrub, New Zealand flax, ornamental vine, Hakonechloa and tobacco plants is all well suited to moist, silty soil.
Improving: Add at least one inch of compost or mulch every year. Concentrate on the surface of your soil to avoid crusting.

Mulch your beds
If the plants are already there, adding mulch to the beds will improve the fertility of the soil, contain weeds and store moisture. Dig out perennial weeds and waterbeds before and after applying. You can use anything organic for mulch, including manure, grass clippings, bark, straw, compost and wood chips. Add a four-inch layer to beds and spread fertiliser before the plants begin to grow in early spring. The best time to do it is after rain or water, so that the soil will contain as much moisture as possible. Don’t mulch around stems or trunks as it can cause rot, and make sure you cover plants with an upturned bucket in order to keep leaves clean.