Some plants adapt to all soils. Others, on the other hand, are very demanding. The most typical example is that of so-called heathergrass plants (rhododendrons, azaleas, etc.) that normally thrive only in acidic conditions. They die and die quickly in limestone soil. You must therefore, before considering a plantation, know your soil.
Determine the nature of the soil in your garden
Two complementary resources are available to you: observation and analysis.
Observation is looking around you, questioning your neighbors. Spontaneous plants give a first piece of information. So grow:
In calcareous earth
Ononis or stinger, borage, sanve or wild mustard, marigold, elderberry, laburnum, cantaurea, sainfoin.
In terra acid
Gorse, heather, foxglove, horsetail, chestnut, sheep sorrel.
In clay soil
Wild chicory, mauve, large-leaved plantain, coltsfoot or pas-d'âne, bulbous buttercup.
In siliceous earth
Matricaria, wild pansy, lanceolate plantain, harvest chrysanthemum.
In wet earth
Cardamen or watercress, ficaire or false reconcule, rush, horsetail, reed.
In dry earth
Cutthroat, nettle, cirse.
With these wild plants, you have a first indication of the nature of your soil, but only one indication. The terrain could be modified by man, superficially or very locally. The plants were able to find in a small place favorable conditions for their establishment. Your judgment may be skewed.
The physical aspect of the soil
The physical aspect of the soil adds to these first observations. A brown or blackish colored earth announces a richness in humus, often a neutral earth or with tendency to acid. A whitish earth is probably rich in limestone. A soil that sticks to shoes or clumps if you mix it contains a lot of clay. Water there
stays on the surface after a heavy rain.
A rough ground to the touch, which crumbles easily, is rich in sand. It dries quickly after a rain.
Look also at your neighbors, ask them what they planted, their successes and failures. Deduce information on the basement of your land. The rooting of certain plants is indeed very deep and the composition of the subsoil is not without a strong influence on their behavior.
If you learn that pear trees, peach trees and rosebushes chlorate, it is because the subsoil is certainly limestone. On the other hand, if the chestnut behaves well, the limestone is absent.
Soil analysis
Usefully complete all these indications with a soil analysis. Have it done by a specialized laboratory that will tell you how to carry out the soil sampling. It is best if the test is applied to the soil and subsoil (to a depth of 80 cm to 1 cm) when planting trees or shrubs.
You will have a good knowledge of your field. From there, two solutions are available to you:
- use plants whose requirements match the nature of your soil;
- modify the soil.
This second solution is very expensive because to be truly valuable, it must interest the soil and the subsoil to a significant depth. It involves the removal and replacement of a considerable volume of land.
More economically, you can simply change the land or improve it on small sites (for example for a heather land plant, or a bed of roses).
In general, humus, in all its forms, is the universal soil improvers.
In acid earthyou must also bring lime or materials containing it. In calcareous earthadd peat, heather or woodpile. In sandy soilLightly give body with clay soil. In contrast, clay soilBring coarse sand at a high dose to lighten it.
By all these modifications you must tend to get closer to a neutral earth or almost, which is neither too acid nor too alkaline. Its pH should be between 6.5 and 7.5. This notation is, it may be said, a measure of the acidity, neutrality or alkalinity of a soil. You find it in all the analyzes. A low figure (pH 5 or 6) indicates a very acidic soil; a strong figure (pH or 8.5), a very alkaline earth. Besides its neutrality, the ideal soil of a garden must be a harmonious mixture of 60 to 70% of sand, 20 to 25% of clay, 5 to 1096 of limestone and 5 to 10% of humus. It is the so-called free land of the best growing regions. Alas, we do not find it everywhere.
Be careful in choosing plants
So, for the most part, taking into account the conditions of your garden and without having to make too much soil changes, it is better to choose plants that behave the best.
Always be careful before starting a plantation, especially of plants that should remain in place for a long time (especially trees and shrubs).
They can grow normally for several years, as long as their roots are in good soil, on the surface, and then quickly withering in contact with the subsoil. You only have to do the planting again: waste of time and money. On the other hand, for the annual plants, do not hesitate to try some tests.
A failure only affects one season and you will often have happy surprises. Many plants are less difficult for the soil than they say.
