What Is The Difference Between Potting Soil And Topsoil?

To have a well flowered and productive garden, it is necessary to know the essential notions. For example, the better the soil, the better it is for the plants. Topsoil refers to soil that is rich in humus. Potting soil, on the other hand, is enriched topsoil mixed with fertilizer such as manure or plant debris. The difference between these two types of soil lies in their composition.

What Is The Difference Between Potting Soil And Topsoil?

Potting Soil: modified topsoil

Potting soil, like topsoil, is both highly prized in terms of planting and crop development. What differentiates topsoil from topsoil is its richness in decomposition products. Indeed, potting soil is essential for the stimulation of the plantation at the beginning. Also, it allows a better development of the roots. Potting soil is very popular for vegetable and horticultural crops. Potting soil differs from topsoil in its properties. In this regard, potting soil must have air and water porosity.

This porosity allows the anchoring of the absorbing organs of the plants as well as their contact with the solutions which are necessary for their growth. The potting soil must also allow a good drainage, which is rare in commercial potting soils. Indeed, it is always necessary to add granulometry sand before using this type of product.

The potting soil is essentially made up of blond and black peat, pine bark, composted wood and coconut fibers to lighten the soil and ensure a good porosity of the medium, topsoil, wetting agents, fertilizing materials, magnesia and sometimes dolomitic lime. The latter is essential to provide calcium to the plant.

Topsoil: humus-rich soil

Topsoil is rich in humus. It is also the soil of the garden which is said to be “natural”. It is the type of soil that is mostly found in gardens and everywhere in nature. The components of topsoil and potting soil are not really different. However, topsoil is artificially obtained by assembling various organic and mineral materials. Topsoil, on the other hand, is of natural origin since it is found in its natural state. By definition, topsoil is the soil that comes from humus-bearing surface areas or deep horizons. Topsoil can be mixed with organic matter of plant origin, organic amendments but also mineral matter.

This is why the “topsoil” found in the market is what we call “garden soil”. It is soil to which amendments and organic matter have been added in order to modify its composition. There are various types of topsoil due to the content of its different components: clay, sand, limestone, humus and frank.

Which potting soil to choose for your plants?

What Is The Difference Between Potting Soil And Topsoil?

Potting soil is generally used as a substrate for potted plants or for cultivation in the ground.

But to optimize your crops, you will first have to choose the type of soil that best suits the plants you want to grow. In this regard, it should be noted that there are different types of soil, each with specific qualities. We distinguish between :

  • Universal potting soil: this is the most common and easiest to find in the market. It contains a lot of composted material and is therefore suitable for planting trees and shrubs. Therefore, it is not recommended to use it for repotting flowering plants or plants that need a good soil pH to grow well.
  • Horticultural potting soil: it is composed mainly of peat and composted manure with a lot of nutrients for the good development of flowers. It can also be used for vegetable gardens or for planting fruit trees.
  • Potting soil for seedlings and transplanting: as its name indicates, this type of potting soil is adapted for seed development thanks to the perlite found in its composition. It also allows repotted plants to easily resume their growth.
  • Heather potting soil: its composition is somewhat similar to that of horticultural potting soil. It is composed of a mixture of acidic peat, leaves, stems and roots of heathers. Use it to acidify calcareous soils and to plant plants that need a low pH soil like camellias or magnolias.
  • Vegetable Garden Potting Soil: with its composted and organic matter, this type of potting soil provides the nutrients needed for growing vegetables.
  • Turfgrass potting soil: this is very fine and should be spread in thin layers over newly sodded areas.
  • What type of topsoil for what purpose?
  • As with topsoil, there are different types of topsoil, each with characteristics adapted to a specific use.

The first type is clay soil which is characterized by a high level of fertilizer with the particularity of retaining rainwater. If you plan to plant plants that do not tolerate water stagnation, you should avoid using clay soil.

Then there is the limestone soil which, unlike the clay soil, is dry. You can use it for rock garden plants or for hardy grass. The sandy soil is permeable and quite easy to drain. It is recommended for root vegetables and perennials.

There is also humus-rich topsoil and free soil. The first one is characterized by its composition rich in fertilizing elements. It is also widely used for its great capacity to store water. You can turn to this type of topsoil for tomatoes, for example, or for indoor plants like camellias. Free soil is made of compost and sandy soil. Unlike the other types, it can be used for different crops.

How is topsoil formed?

Topsoil is the layer of soil a few centimeters below the surface just below humus. It is simply soil that is about 20 centimeters deep that belongs to nature, gardens, fields or forests.

If you dig the first few centimeters of natural soil, you will first come across humus. This is the “larder”, composed mainly of dead plants and animals, microorganisms helping to decompose organic matter. The micro-organisms then move deeper into the topsoil layer and provide the nutrients that make it rich, like a kind of “compost”. Among these micro-organisms, you will find fungi and micro-arthropods that crumble and help the degradation of organic matter and earthworms that maintain the porosity by digging galleries.

We are faced with a natural recycling process, humus hosts a whole biodiversity that feeds and enriches the topsoil, this biodiversity then dies out to make way for a new cycle. The topsoil comes from the process of humification, in other words, the metamorphosis of fresh organic matter into humus. As Antoine Lavoisier said, “nothing is lost, nothing is created, everything is transformed.”

What is topsoil and why use it?

Topsoil is composed of topsoil improved with compost and sometimes manure. It is often referred to as a substrate or growing medium to which different mixtures are added depending on the use you wish to make of it. For this reason, there are several types of potting soils. So, if you want to grow plants that need a lot of water or on the contrary that absolutely must be drained, you will not turn to the same soil.

It is mostly used to replace soil that is too poor in nutrients for crops and also for repotting above ground plantings. As you can see, each potting soil will meet the specific needs of your plants. You will need to find out about them beforehand in order to offer them the most suitable substrate.

Universal potting soil is perfectly suited for soil-based crops, mainly for plants and trees, but much less recommended for above-ground plantings.

Choose rather a horticultural potting soil for your pots and planters. It will also be perfect for growing your vegetables. You want to try to transplant plants? The seedling potting soil will be ideal to accompany the development of your cuttings!

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