Before planting
Understand your soil
Soil is the foundation of the garden. Knowing how to read it means knowing what to plant, what to pair, what to improve and which guild to build.
Identify your soil by hand
Four simple tests to do in the garden, with no equipment.
The touch test
Rub a handful of moist soil between your fingers. Smooth and sticky = clay. Rough and gritty = sandy. Soft like flour = silty.
The ball test
Form a moist ball. It holds and moulds = clay. It crumbles = sand. It holds but cracks = balanced.
The visual test
Dark brown / orange = rich clay. Light beige / blond = sand or silt (the touch test tells them apart). Grey-white with small stones = chalky.
The vinegar test
Pour a few drops of white vinegar on dry soil. If it fizzes, the soil contains active lime.
Texture: three main families
Grain size, from sand (the coarsest) to silt (in between) to clay (the finest), governs drainage, water reserve and how easy the soil is to work.
Clay soil
Heavy and sticky, but rich in minerals: a soil you have to earn.
Sandy soil
Light, warm, free-draining: it works well but wears out fast.
Silty soil
Soft as flour, fertile and easy, but it forms a surface cap.
Chemistry: more acidic or more chalky?
Whatever its texture, a soil leans acidic or chalky depending on its pH. The very same silt can be acidic or chalky, and pH is often what decides which plants truly thrive.
Chalky soil
Crumbly, alkaline, easy to work, but often shallow.
Acidic soil
Low pH (< 7): the realm of heath (ericaceous) plants.
What soil near you?
A few broad regional trends to guide you. Pick your country, spot the zone that looks like yours, then open the matching soil entry.
A trend, not a diagnosis. These broad regional trends draw on national and European soil maps (GIS Sol / INRAE in France, ESDAC and national databases elsewhere), drawn at small scale: they cannot be used at garden scale. A few hundred metres away, your soil may be entirely different. Nothing replaces observing your own ground: do the touch and ball tests described above, or a soil analysis for an important project.
11 regions found
Chalky Champagne (Marne, Aube)
high confidenceChalky (chalk)
Reaction: Alkaline
Outcropping Cretaceous chalk: shallow, free-draining, chalky soils.
Source: IGN (sylvoécorégion Champagne crayeuse) ; GIS Sol / INRAE
See the closest soil: ChalkyBeauce, Brie, Picardy plateaus
high confidenceSilty (loess) over limestone
Reaction: Neutral to slightly acid
A veneer of wind-blown silt over limestone: great wheat lands, neither truly sandy nor clayey (silt is intermediate).
Source: INRAE (Mots de l'agronomie, Limon) ; D. Baize (Luvisols)
See the closest soil: SiltyBrittany & Armorican Massif
medium confidenceAcid, silty at the surface (sand over granite, clay over schist)
Reaction: Acid
A siliceous crystalline basement under a surface silt: acidity is the constant trait, the texture varies a lot from one plot to another.
Source: Observatoire de l'environnement en Bretagne ; « Sols de Bretagne »
See the closest soil: AcidicLandes de Gascogne (Gironde, Landes)
high confidenceSandy
Reaction: Acid
Quaternary wind-blown sands, often moist (podzols, an iron-pan layer).
Source: INRAE (sols du massif des Landes de Gascogne) ; IGN
See the closest soil: SandySologne
high confidenceSandy to clay-sandy, moist
Reaction: Acid
Fluvio-lacustrine deposits; impermeable clay at depth (hence the ponds).
Source: IGN (sylvoécorégion Sologne-Orléanais)
See the closest soil: SandyAlsace Plain
high confidenceSilty (loess), very fertile
Reaction: Neutral to acid
A vast cover of Quaternary loess in the Rhine rift.
Source: Référentiel Régional Pédologique Alsace (GIS Sol / INRAE)
See the closest soil: SiltyChalky Provence & Languedoc
medium confidenceChalky (often stony clay-limestone)
Reaction: Alkaline
Plateaus and garrigue on limestone, dry and shallow soils, but neighbouring valleys and 'red earths' are very different.
Source: A. Ruellan (IRD), Les sols calcaires
See the closest soil: ChalkySouth-West hills (Gers, Toulouse area)
indicative confidenceClay-limestone 'terreforts' (slopes) and acid clay-sandy 'boulbènes' (terraces)
Reaction: Variable
Two contrasting soils interlocked: heavy terreforts on the hills, lighter and acid boulbènes on the terraces.
Source: IRD (étude des boulbènes du Sud-Ouest)
See the closest soil: ClayAlluvial plains & valleys (Loire, Garonne, Rhône, Saône)
medium confidenceSilty-clay (fertile alluvium)
Reaction: Often neutral
Low terraces of the great rivers, a shallow water table; narrow ribbons, hard to generalise at a large scale.
Source: BRGM (Infoterre, cartographie des alluvions)
See the closest soil: SiltyMassif Central & crystalline Vosges
medium confidenceAcid, sandy to silty over the basement
Reaction: Acid
Siliceous granites and metamorphic rocks; sandstone in the Vosges. Acidity dominates, the texture varies.
Source: Persée (bilans d'altération des sols vosgiens sur granite) ; BRGM (cartes géologiques du Massif central)
See the closest soil: AcidicJura, Prealps, Grands Causses
medium confidenceChalky
Reaction: Alkaline to neutral
Mountain limestones (Mesozoic); strong variability between slopes and flats.
Source: BRGM (cartes géologiques) ; notices géologiques régionales
See the closest soil: ChalkyThe garden's logic
Once the soil is understood, everything follows naturally.