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If you want to make your garden a success, it’s essential to know its soil type. Plants have different requirements regarding moisture, permeability and pH value. In short: different plants thrive in different soil types.

Types of soil are classified by grain size, colour, the amount of organic material and the minerals in it. Also, the percentage of sand, clay and silt is important and lastly, you should know the pH-value of your garden soil.

Nutrition

A plant cannot absorb water and fertiliser in one go. It can’t drink a whole can of water in one gulp and eat a whole load of fertiliser all at once. The soil’s important task is to store liquid and nutrients and deliver them to the plants so that they can have little snacks.

Also, plants cannot take in fertiliser in solid form. To make the best use of nutrients, plants need water as a solvent agent. A plant “eats” and “drinks” mainly with its root system but also little stomata in the leaves absorb a bit of water and nutrients.

The soil is a pantry

The soil is the plant’s pantry. In it, there are cavities (pores) where water, released nutrients and oxygen are stored. The cavities between particles are of different sizes, depending on the soil structure. A fine-textured soil has smaller cavities than a coarse-grained soil. The smaller the cavities, the better the soil can bind nutrients and water. If the cavities are large, water runs through the soil.

Soil structure

Different soil characteristics provide the plants with different prerequisites. When you know and understand your soil, you can easily maintain or improve it and thus offer your plants a suitable environment.

Naturally, soil is built “from below” as well as “from above. The lower part of the soil is based on the bordering rock. Basic mountain rock that was rich in minerals, has weathered and crumbled during millions of years. The upper part, which is known as mother soil, was mixed with organic material from animals and plants that had decomposed and turned into humus.

Thus, the solid parts in the soil consist of minerals and organic material. Between the solid particles, there are pores. At best there are as many pores as particles. The pores’ task is to store oxygen, liquid and nutrients and carry them to the plants’ roots.

Different grain sizes

Rock erodes and breaks down into particles of different particles. The size decreases from stone to gravel, sand and silt to clay. Most garden soils are a mixture of mineral soil and organic material.

Soil types

It is practical to categorize the soil with terms like “silty, slightly loamy soil”. By that, we know what we have and what we can do to improve the soil. Different soils have advantages and disadvantages, especially regarding what you want to plant.

The most common definition of soil types is based on pure mineral soil and uses the grain size as a description.

Sandy soil

Sandy soil has large particles; it is light and porous and can be worked easily. It warms up quickly in spring and cools quickly down in autumn. That makes it especially suitable for sensitive plants that must go into hibernation early to survive the cold season.

On the other hand, sandy soil badly stores liquid and nutrients. It dries out quickly and must be watered often.

Silty soil

The size of the silt grain lies between sand and clay, being smaller than sand and larger than clay. By covering the silty soil with organic material like leaves or bark mull encrustation can be prevented.

Loamy or clayey soil

Loamy soil has small particles that encrust easily. If loamy soil has a clay content of more than 40 % it is practically impenetrable. Loamy soil is nutrient-dense and stores moisture well.

Loamy soil takes longer to get warm in spring but also holds the warmth longer in autumn. Loamy soil has few cavities and thus is sensitive to pressure and trampling.

Chalky soil

As the name indicates chalky soils contain a relatively large amount of chalk which makes them alkaline and thus not very good for plants. They have little nutrients and tend to dry out easily but become a rain-slicked, loamy mass after heavy rains.

Every type of soil can be improved. The goal is to make sure that it can hold optimal amounts of moisture, nutrients and oxygen optimally. It’s great for any soil to add organic material.

How to find out soil types

Often, it’s enough to have a look at the soil to determine its type but to be sure, you can try out the following:

The rolling test

Take a bit of soil (about 1 tablespoon) and roll it between your hands to a “sausage”. If the soil doesn’t form a roll of any kind, you probably have sandy soil. The thinner the “sausage”, the higher the clay content in the soil. Loamy soil yields a roll of 1 mm diameter, 4 – 5 mm characterise silty soil.

The shaking test

Fill a large glass jar with a handful of soil and add water at a ratio of 1 part soil and 2 parts water. Shake it well to mix the soil and water and let it set for 1 – 2 days without disturbing it. Slowly the soil particles will sink to the bottom and layer up there.

Sandy soil leaves the water almost clear; the particles have layered at the bottom.

Silty soil leaves cloudy water and most of the particles at the bottom.

Chalky soil leaves a layer of grit-like particles at the bottom of the jar; the water is a light grey.

Loamy soil shows relatively clear water and the particles are layered by grain size at the bottom with the smallest particles on top.

This is the result of the shaking test with my garden soil. Can you see the layers?

pH value

Soil can be acid, alkaline or neutral which can be determined with a pH-test. The pH scale goes from 1 = acid to 14 = alkaline. The middle value 7 indicates neutral. Most plants prefer a pH value between 5.5 and 7.5, with the ideal value between 6 and 6.5. The pH value impacts the plants’ nutrient uptake.

Extreme pH values under 3 and above 8 provide no suitable environment for plants as nutrients become encased and can’t be taken up by the plants. And then it doesn’t matter if or what you use to fertilise.

The pH value also influences the soil’s structure and microorganisms. And, finally, a balanced pH prevents the absorption of dangerous heavy metals from the soil.

First, however, you must know your garden soil’s pH value. To determine that, you can either ask a lab to make a soil analysis or buy some litmus paper and do the tests yourself.

Measuring the pH value

1. Remove the upper soil layer (approx. 3 centimetres / 1 inch) and dig 20 cm / 8 inches deep. You need about 200 ml / 0.5 lb soil.

2. Put the soil into a large jar with a lid. Mix the soil at a ratio of 2/3 water to 1/3 soil with distilled water. (It’s important to use distilled water to make sure that the water’s pH value does not affect the test)

3. Close the jar and shake it for at least 2 minutes.

4. Let the mixture set for at least 10 minutes.

5. Insert the litmus paper into the water above the sediment.

6. Read the result and note it down. Take several soil samples from different places in your garden.

Compare the colour of the litmus paper with the indicator.

Favourable pH-values

Greens: 6.5 – 7.0

Cabbage: 6.5 – 7.5

Potatoes: 5.5 – 6.5

Raspberries: 5.5 – 6.5

Strawberries: 6.0 – 7.0

Berry bushes: 6.0 – 7.0

Blueberries: 5.0

How to improve your soil type

When you know your garden’s soil type, you can take measures to improve it by adding organic materials like compost and manure. Stay patient! building good soil requires time.

Sandy soil

As said before, sandy soil can’t store water very well because due to the sand’s large grain size, water will run through it. To improve moisture retention capacity, we can dig in plenty of bulky organic material like compost or well-rotted manure.

Always keep the soil surface well covered, either with mulch or with groundcover plants. Sow green manure between vegetables, cut it off when it becomes too large and use it as mulch. Leave the roots in the earth. They will stabilise the soil and help to store moisture.

Nevertheless, sandy soil will always need more fertiliser than other soil types. Fertilise sandy soil several times during the cultivation season and with relatively low amounts. If you give sandy soil more nutrients than it can store, they will be washed out.

Silty soil

Silty soil has a lot of nutrients and holds moisture well. It can be easily cultivated as long as it is well drained.

To improve drainage, dig in organic material like compost.

Chalky soil

Chalky soils have larger particles and are stonier than other soils. It is alkaline and, depending on its clay content, may be light or heavy.

First, we must lower the pH value by digging in lots of organic materials like compost or well-rotten manure but also half-rotten compost of conifers. Mulching with conifers in addition to other organic materials also improves the pH value long-term.

To break up the soil and add nitrogen, sowing leguminous plants is recommended.

Loamy soil

Loamy soil is usually a great mixture of sand, silt and clay. It’s nutritious and holds water easily. It warms up relatively quickly in spring and is easily cultivated.

Although loamy soil is already nutritious, it’s important to keep it that way. This is usually carried out best by adding organic material like compost and manure to the soil, making sure that it’s always covered with plants (green manure if necessary) and well-mulched. To aerate the soil, dig into it with a digging fork and jiggle it slightly. This is best done in autumn and early spring to ensure that enough oxygen gets into the soil without digging it up.

What to do to raise your soil’s pH?

If your soil’s pH is too low, that is if your soil is too acidic, you can add lime to your soil. But be careful, a too-high pH is equally unfavourable as a too-low pH. There are, however, good reasons to add limestone to your garden: it adds micronutrients to your soil which results in the plants not taking up too many heavy metals. especially loamy soil is better aired, more loose and thus easier for the roots to penetrate.

Different forms of lime

Lime is sold in different grain sizes. Powdered limestone has the smallest particles, granulated limestone consists of processed powdered limestone. the latter does not make a lot of dust and dissolves quickly into the soil. You can also buy lime chippings, but they dissolve relatively slowly.

Time and dosage

The best seasons to add lime are autumn and winter when rain and snow transport the lime into the soil.

The amount of lime you need depends on the soil type. Loamy soils usually need more to adjust the pH, sandy soils need less. As the lime products differ in their ingredients, you must follow the instructions valid for your product. If you prepare a new garden, you’ll need more lime than just for maintenance.

Conclusion

The first step for a healthy garden is determining your soil type. Different soil types require different improvement and maintenance methods. Every soil can be improved so that your garden provides the best conditions for your plants.