Down to Earth

Autumn is one of the best times of the year for adding new plants to the garden. The soil is wet and warm and anything planted now will have a chance to settle down before it has to start growing again in spring.

This year’s dying foliage can be easily cleared away to reveal those gaps in the borders where new plants are needed to fill out the show and spring bulbs unearthed by accident can be replanted without coming to any harm.

But before planting anything new it’s worth taking stock of what kind of soil you’ve got and using this knowledge to help guide your plant choices.

Soil types range from light sand to clay. Sand is free-draining and low in nutrients while clay is highly fertile but prone to setting like concrete during periods of drought. It is slow to warm up in spring and during wet weather it holds high levels of moisture.

Between these two extremes lie silt and, best of all, loam, the sort of dark and crumbly soil that you find in old walled gardens where generations of cultivation and enrichment have created the perfect conditions for almost everything to flourish.

Chalky soils occur across some of Scotland’s richest farmland and contain high levels of lime, making them good for growing many kinds of vegetable and lime-loving plants such as Lilac.

Then there is peat, which features predominantly along the west coast and in the Highlands and is extremely acidic, which is good news if you want to grow blueberries.

Whatever your soil type it can be improved by frequent applications of organic material. Leaf mould, home made compost, local authority green waste and well-rotted farmyard manure will help to enrich and bulk up light soils and make heavy soils more free-draining.  And you don’t even need to go to the trouble of digging any of these in. Simply spread over the surface as a thick mulch, taking care to avoid the trunks of shrubs and trees and, over time, the worms will do the rest.

SAND
Pour a bucket of water over sand and the water will almost instantly disappear. This kind of soil is quick to warm up in spring but equally quick to dry out during hot spells, making it ideal for lavender, which often struggles in our damp climate.

In fact many Mediterranean plants will flourish here and a good way to tell if something is suitable is by looking at the leaves. Narrow, grey foliage is a sure sign that you are dealing with a plant that doesn’t like to get it’s feet wet. You can create a quick splash on sandy soil by sowing annuals, including Poppies and Nigella.

Plants for sandy soil: Rosemary, Eryngium, Sea Kale, Verbena bonariensis, Chaenomeles (Japanese Quince.)

SILT
Silty soil is similar to sand, but not quite so free-draining so is more effective at holding both water and nutrients. This is useful if you favour the sort of dense planting which needs a good level of organic material in order to retain its vigour. Both silt and sand provide good conditions for tulips, alliums and other bulbs, many of which decline if grown in heavier soil.

Plants for silty soil: Dianthus, Euphorbia characias subs. Wulfenii, Eremurus, Forsythia, Geranium, Acanthus.

CHALK
Chalky soil is light in colour and both nutrient and moisture levels may vary. It is impossible to acidify chalk, so any attempts to grow camellias or rhododendrons will be met with failure and even growing them in containers will only bring short-term results unless they are planted in ericaceous compost and watered only with rain water. However many other plants will grow quite happily in alkaline conditions.

Plants for chalky soil: Ceanothus, Clematis, Flowering Cherry, Buddleja, Aster.

LOAM
If you were to examine loam under a microscope, you’d find a mixture of large and fine soil grains as well as small blobs of a jelly-like substance. This is humus, which is what helps to give loam its wonderful structure, resistant to both waterlogging and drought. Shrubs and perennials of all kinds are happy in loam so gardeners with this kind of soil have a very wide of palette of plants to choose from.

Plants for loamy soil: Narcissus, Delphinium, Geum, Peony, Anemone, Hydrangea, Crocosmia.

CLAY
Although it can be difficult to work, clay soil is rich in organic matter and is good for plants that don’t like their roots to dry output, making it suitable for Hostas, Astilbes and a succession of tough shrubs such as Cotoneaster and Mahonia. Roses love it too.

Digging planting holes into clay can sometimes create sumps that fill up with water, so a better solution is to build up the soil level with organic material and plant on top of it, allowing the roots to find their own way into the clay bel

Plants for clay soil: Acer palmatum, Malus (crab apple), Persicaria, Pyracantha, Alchemilla mollis, Helleborus.

PEAT
There are places in Scotland where the soil is comprised mostly of peat and aside from native heather, all kinds of acid-loving plants will grow contentedly here so long as they are not waterlogged. To get the best out of peat you may have to install drainage

Plants for peaty soil: Rhododendron, Camellia, Erica, Hamamellis mollis (Witch hazel), Sambucus nigra (black Elder.)