What Soil Should Be in a Greenhouse? A Complete Guide to Choosing and Preparing Soil

The soil in the greenhouse is the basis for healthy plant growth and a high yield. If the soil in the open ground is renewed naturally, then in the closed space of the greenhouse it is gradually depleted and requires special attention. What should the soil in the greenhouse be like so that the plants grow strong and the harvest is stable? What mistakes do gardeners make when preparing the soil? Let's look into it in detail.

Basic requirements for soil in a greenhouse

The ideal soil for a greenhouse should provide plants with:

• The optimal structure is loose, breathable, non-caking, capable of retaining moisture but not allowing it to stagnate.
• Good moisture capacity - retain moisture, but do not allow it to become over-watered, which leads to root rot.
• Rich composition – contains all the necessary macro- and microelements that provide nutrition to plants.
• Neutral or slightly acidic pH – 6.0 to 7.0 for most vegetable crops, as strong acidity or alkalinity interferes with nutrient absorption.
• Pathogen-free – the soil should be free of fungi, nematodes, pests and pathogens that can spread quickly in greenhouse conditions.

Expert advice: If the soil in the greenhouse is too dense or heavy, add sand, peat or vermiculite - this will improve its structure and air permeability. Check the drainage to avoid stagnant water.

Composition and types of soil mixtures

You can prepare the soil in the greenhouse yourself or use ready-made soil mixtures adapted to specific crops. Let's look at the main components of high-quality greenhouse soil and their effect on plants.

Main components

• Chernozem is a highly nutritious soil with good water-holding capacity, but requires regular loosening, as it becomes compacted over time.
• Peat – retains moisture, makes the soil light, but has an acidic reaction. To neutralize the acidity, lime or dolomite flour is added to it.
• Sand – improves drainage and reduces soil density, preventing it from compacting.
• Humus is rich in organic matter, accelerates plant growth and increases fertility.
• Vermiculite and perlite – increase aeration, prevent soil compaction and promote even distribution of moisture.
• Ash is a natural source of potassium and phosphorus, helps reduce soil acidity.

Optimal soil mixtures for different crops

• For tomatoes: 40% humus, 30% black soil, 20% sand, 10% ash. This composition provides good nutrition and aeration.
• For cucumbers: 50% peat, 30% humus, 15% sand, 5% vermiculite. Cucumbers require light and moisture-retentive soil.
• For peppers and eggplants: 50% black soil, 30% humus, 15% peat, 5% ash. This mixture provides a powerful root system.

Expert advice: Before planting, check the acidity of the soil with pH tests. The optimal pH for most vegetables is 6.0-6.5. If it is higher, add sulfur; if it is lower, add lime.

Preparing the soil in the greenhouse before the season

Soil preparation is an important stage that affects crop yield. Even if the soil was fertile last year, it needs to be renewed before the new season.

Replacing or renewing the soil

• Partial replacement: If the soil in the greenhouse has been used for more than 3 years, it is recommended to replace the top layer (15-20 cm) with a new substrate.
• Complete replacement: Every 5-6 years the soil is completely renewed, as it loses fertility and accumulates pathogenic microorganisms.

Soil disinfection

Old soil may contain fungi, bacteria and pest larvae. The main methods of disinfection are:

• Pouring a solution of potassium permanganate destroys pathogens (1 g per 10 l of water).
• Steam heating is effective in killing pest larvae.
• Fumigation with sulfur checkers – destroys fungi, bacteria and insects.

Expert advice: If the plants were sick last season, be sure to replace the soil and disinfect the greenhouse. You can also use biofungicides such as Fitosporin.

Improving the structure and nutrition of the soil

Even the most fertile soil becomes depleted over time. How can its properties be restored?

Organic fertilizers

• Humus – improves structure, saturates soil with nitrogen.
• Compost is rich in microorganisms that are beneficial to the soil.
• Wood ash is a source of potassium and phosphorus.

Mineral fertilizers

• Nitrogen (urea, saltpeter) – stimulates plant growth.
• Phosphorus (superphosphate) – strengthens the root system.
• Potassium (potassium sulfate, potassium magnesium sulfate) – improves flowering and fruiting.

Expert advice: Organic matter improves the soil structure in the long term, while mineral fertilizers provide a quick effect, so it is better to combine both options.

Selecting and preparing soil for a greenhouse

The right soil in a greenhouse is the key to healthy plant growth and a bountiful harvest. The main principles of its preparation:

• Use a loose, breathable and nutritious substrate.
• Regularly refresh the soil and add organic and mineral fertilizers.
• Monitor pH levels and disinfect soil before planting.
• Avoid preparation mistakes such as over-fertilizing or using heavy soil.

Want to create ideal conditions for growing vegetables in a greenhouse? Greenhouses from NovaTeplitsa will help you maintain a stable microclimate, and high-quality soil preparation will ensure a high yield. Check out our greenhouses on our website and start the season with the best conditions for plants!