Gardener’s Guide to Soil Types
The type of soil in the garden is governed by the proportion of sand, silt, clay and organic matter. The simplest method of assessing the type is to rub a small sample of moist (not wet) soil between your thumb and forefinger. A gritty feeling indicates sand. Smoothness indicates silt or organic matter; these can be distinguished from each other by colour; organic matter being dark brown. Clay also feels smooth but in addition, the surface becomes polished when rubbed. It also moulds easily instead of crumbling.
Sandy Soils.
These soils lack humus (decayed vegetable and animal material) and hence require frequent additions of peat or manure. In addition, they dry out rapidly (although the water holding capacity of these soils can be improved by the addition of organic manures). Such soils are, however, easy to cultivate and provide good drainage, the latter allowing the soil to warm up earlier in the spring. This allows earlier spring sowing and planting than would be possible with a heavy type of soil.
Clay Soils.
These soils are characterised by being heavy and sticky. They dry out very slowly in the spring, are therefore slow to warm up and hence unsuitable for early spring cultivations. When dry they form hard clods which further complicate cultivations. These problems can, however, be overcome to some degree by the addition of organic manures and planting composts which facilitate improved drainage. Lime can also be used for this purpose, but care is needed to ensure that the soil does not become excessively alkaline.
Loams.
Loams contain roughly equal parts of sand, silt and clay. They develop clods when cultivated immediately after rain but break down fairly easily when dry. They are retentive of both moisture and nutrients and can be said to be amongst the most fertile soils in the country. Loams can further be classified into sandy loams, clay loams, etc., the classification obviously depending on the predominating content of either sand or clay.
Peaty Soils.
These soils contain a high proportion of organic matter, are brown or black in colour and rich in nitrogen. They can absorb many times their own weight of water but are easily worked after rain. Peats are very variable, some being acidic, others alkaline. This latter point should be considered when planting lime hating subjects.
Lime‑free peats are ideal for all lime hating plants, which group includes rhododendrons azaleas and certain heathers (erica).
Growing Lime‑hating Subjects in Soil Containing Lime.
For individual shrubs a hole 1m wide and 45cm deep should be dug, then filled with a mixture of lime‑free soil and a planting compost or well rotted leaf mould. After planting, mulch with chipped bark or cocoa shells. If the soil is still limy then Sequestered Iron may be applied, and this can be obtained from our garden centres. For small growing ground covering shrubs which dislike lime, the whole area should be prepared as above to a depth of about 20cm.
Nutrients.
It has been established that for healthy growth all plants require certain essential mineral nutrients. These nutrients can be provided by either the addition of fertilizer to the soil, or liquid fertilizer to the plant.
All of our garden centres carry extensive stocks of organic and inorganic fertilizers, as well as an assortment of composts.