How to Use Trichoderma in a Greenhouse: Detailed Solution Preparation Guide

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Closed greenhouse soil is an ideal incubator not only for tomatoes and cucumbers but also for dangerous pathogens. High humidity and stable warmth provoke the rapid development of late blight, cladosporiosis, and root rots. Under such conditions, the soil quickly depletes and accumulates an infectious background.

The soil antagonist fungus Trichoderma is an effective biofungicide and natural biostimulant capable of solving these problems comprehensively. Introducing the preparation into greenhouse practice solves two key tasks:

Biological protection: The fungus suppresses disease pathogens by releasing natural antibiotics and destroying pathogen mycelium.
Fertility enhancement: Trichoderma accelerates organic matter decomposition, converting nutrients into a form accessible to the roots.

Regularly revitalizing the soil with this biopreparation allows for the abandonment of harsh chemicals and guarantees the safety of your harvest.

Section 1: Foundation of Knowledge — How and Why Trichoderma Works

For the biopreparation to work at one hundred percent in closed ground, it is important to understand the biological essence of our invisible ally. The green hyphomycete fungus is not just a "medicine" from a packet, but a living, active organism with its own needs and survival mechanisms. In a greenhouse, where a special microclimate is created, its behavior directly determines the health of tomatoes, cucumbers, and other crops.

In this section, we will examine the inner workings of Trichoderma. You will learn the ways this soil antagonist fungus suppresses pathogens of dangerous diseases, such as late blight and root rots, and under what environmental conditions it maintains maximum activity, helping you revitalize the soil without using harsh chemicals.

1.1. Trichoderma as a Soil Antibiotic: Mechanism of Action

The fungus Trichoderma is an active soil antagonist fungus that works in the rhizosphere according to the "find and neutralize" principle. This natural biofungicide uses three main mechanisms for suppressing disease pathogens:

Direct parasitism (mycoparasitism). The green hyphomycete fungus recognizes phytopathogens (such as pathogens of late blight, fusarium, or root rots), wraps their mycelium with its hyphae, and releases enzymes (chitinases and glucanases) that literally dissolve the enemy's cell walls.
Antibiosis. Trichoderma actively synthesizes natural antibiotics and toxic peptides (gliotoxin, trichodermin, viridin). These block the life processes of pathogenic fungi and bacteria within its habitat radius.
Resource competition. The fungus instantly colonizes organic residues and the plant root system, absorbing nutrients and oxygen faster than harmful microorganisms. Pathogens simply die from nutrient deficiency.

Thanks to this triple action, Trichoderma not only protects the crops but also conducts a deep revitalization of the greenhouse soil.

1.2. Survival Conditions and Optimal Temperature: How to Tell if Your Preparation is Alive

For the soil antagonist fungus to work at full capacity in the greenhouse, it requires strictly defined conditions. Trichoderma is a living organism, and its effectiveness directly depends on the microclimate in the rhizosphere.

Temperature regime: Active fungal development begins at a soil temperature of +10 °C. The optimal range for vigorous mycelial growth and the production of protective substances is +15...+28 °C. When the temperature drops below +8 °C, Trichoderma enters a dormant state (spores), and at temperatures above +35 °C, its life activity is sharply suppressed.
Humidity and acidity: The fungus is extremely moisture-loving. Spores will not germinate in dry soil, so regular moderate watering is mandatory. The optimal soil pH level for colonization is from 5.0 to 7.0 (slightly acidic and neutral environment).

How to check the viability of the preparation at home?

Commercially available biofungicides (powders, tablets like Gliocladine, or liquid concentrates) can lose activity if stored improperly. The quality of the preparation can be checked with a simple test:

Boil a handful of pearl barley or brown rice without salt until semi-cooked, rinse, and cool.
Place the grain in a clean glass jar, sprinkle with a pinch of the preparation being tested, and cover with a clean, breathable cloth.
Place the container in a dark, warm place (+22...+25 °C).

After 3–5 days, a white fluffy coating should appear on the grains, which will soon turn the characteristic emerald-green color and acquire a pleasant fungal smell. If the substrate is covered with black or yellow mold or remains unchanged—the preparation is of poor quality or expired.

Section 2: Preparing the Base — Inoculation and Launching the Biological Culture

Moving from theory to practice, it is important to decide on the source of the biopreparation. The effectiveness of revitalizing greenhouse soil directly depends on the quality and concentration of spores that enter the plant rhizosphere. Every gardener faces a choice: trust ready-made industrial compositions or master a simple home laboratory to cultivate the antagonist fungus on available substrates.

Regardless of the chosen path, launching biological activity begins with proper preparation. For Trichoderma to immediately start suppressing late blight and root rots, the dry spores must be "awakened." Let's examine how to profitably obtain a viable culture and correctly convert it into an active liquid form.

2.1. Comparing Sources: Commercial Preparations vs. Self-Cultivation (on Perlite/Pearl Barley)

The choice between ready-made store products and home cultivation of the antagonist fungus depends on the size of your greenhouse, your budget, and your willingness to spend time on laboratory procedures.

Commercial Preparations (Trichodermin, Gliocladine, Trichoderma Viride):

Advantages: Guaranteed strain purity, absence of extraneous pathogenic microflora, and speed of application. This is an ideal biofungicide for spot application in planting holes when transplanting tomato and cucumber seedlings.
Disadvantages: High cost when treating large greenhouse areas, as well as the risk of purchasing an inactive preparation due to improper warehouse storage.

Self-Cultivation (on pearl barley or perlite):

Advantages: Virtually zero cost. One teaspoon of purchased powder can yield kilograms of active mycelium, enough for the total revitalization of the soil in the entire greenhouse complex.
Disadvantages: Requires strict adherence to sterility. With the slightest error, dangerous Aspergillus or Penicillium will grow on the substrate instead of Trichoderma.

For local seedling protection, it is safer to use a certified commercial biopreparation, while for large-scale soil treatment, it is better to master home propagation on sterilized grain.

2.2. Step-by-Step Guide to Preparing the Mother Solution: From Powder to Activated Suspension

Preparing the active mother solution is a critical step. Simply pouring dry powder into the watering tank is ineffective: the fungal spores require time to "wake up" and transition into the vegetative form.

Step-by-Step Algorithm for Activating Dry Biopreparation (Using Trichoderma as an Example):

Water Preparation: Take 1 liter of lukewarm (22–25 °C) non-chlorinated water (settled or rainwater). The optimal pH level is 5.5–6.5.
Nutrient Medium: Add 1 tablespoon of sugar, molasses, or liquid humate to the water. This will serve as an easily accessible source of carbohydrates for a quick start of the microflora.
Preparation Addition: Pour in the dry trichoderma powder (standard dosage is 10–20 g per 1 L of water for the mother concentrate) and mix thoroughly until all clumps disappear.
Incubation: Leave the container slightly open in a warm, dark place for 12–24 hours. The appearance of a slight yeast odor or bubbles indicates that the spores have germinated, and you have a viable activated suspension.

The resulting mother solution is diluted in clean water to obtain the working solution (usually 100–150 ml of concentrate per 10 liters of water) immediately before application.

Section 3: Manual — Applying Trichoderma in the Greenhouse Complex

Transferring the active trichoderma culture from the prepared mother solution directly into the greenhouse soil is a decisive stage that requires a systematic approach. In closed ground, where the infection background is traditionally higher, this beneficial soil fungal antagonist becomes the main shield for nightshade and cucurbit crops. The effectiveness of biocontrol directly depends on the correct application of the preparation at different stages of plant life.

For the beneficial mycelium to successfully colonize the root zone and suppress pathogens, the treatment schedule must be strictly followed. Below are proven practical schemes for applying trichoderma, adapted to specific developmental phases of greenhouse plantings.

3.1. For Sowing and Seedlings: Ideal Application Scheme in Holes and Soil

At the sowing and seedling stage, trichoderma lays the foundation for the immunity of future tomatoes and cucumbers. Introducing the biopreparation at early stages minimizes the risk of developing 'damping off' and root rots.

Scheme 1: Pre-sowing Seed Treatment
To disinfect and stimulate growth, soak the seeds in the working solution (3–5 g of powder or 20 ml of liquid mother concentrate per 1 L of settled water). Exposure time:

Small seeds (tomatoes, eggplant) — 1 hour;
Large seeds (cucumbers, zucchini) — 2 hours.
After the procedure, dry the seeds until crumbly in the shade and sow immediately.

Scheme 2: Enriching Seedling Soil
When mixing the soil substrate, add the dry biocontrol agent (e.g., on zeolite or perlite) at a rate of 5–10 g per 10 L of substrate. When transplanting seedlings into individual pots up to 0.5 L, place 1 tablet of Gliocladin at a depth of 1–1.5 cm directly into the root zone.

Scheme 3: Transplanting Seedlings into Greenhouse Holes
When moving plants to permanent beds, use one of the following methods:

Dry Method: Apply 2–3 g of commercial preparation (or 1 tablespoon of homemade trichoderma on perlite) to each hole, making sure to mix it with the soil.
Liquid Method: Water the prepared holes with the working solution (100 ml of activated mother solution per 10 L of water) at a rate of 150–200 ml per plant immediately before planting.

3.2. For Adult Plants and Soil: Proper Root Watering and Spraying

For adult tomatoes, cucumbers, and peppers in the greenhouse, regular support of trichoderma activity is the key to reliable protection against late blight, alternariosis, and root rots.

Root Watering (Soil Remediation):

Working Solution: Dilute 100–150 ml of activated mother solution in 10 L of lukewarm (20–24 °C) settled water.
Application Rate: Apply 0.5–1 L of the mixture under each plant. Watering must be done exclusively on moist soil, as spores quickly die in dry environments.
Frequency: Repeat the treatment every 2 weeks throughout the entire growing season.

Preventive Spraying:
Treating the foliage creates a protective barrier against pathogens on the aerial parts.

Preparation: Use the same working solution, pre-filtering it through cheesecloth to prevent clogging the sprayer nozzles.
Conditions: Spray the plants in the evening or on cloudy days. Direct sunlight and UV rays are harmful to the living fungal culture.

Section 4: Integration into the Protection System — Trichoderma in a Comprehensive Approach

Successful application of trichoderma in the greenhouse is impossible in isolation. In real gardening practice, this beneficial soil fungal antagonist inevitably encounters other elements of plant protection—from popular biopreparations to seasonal structural disinfectants. To transform scattered waterings into a stable ecosystem, it is necessary to correctly integrate the green hypocreal fungus into the overall care calendar.

Integrating the biocontrol agent into a comprehensive approach requires understanding biological relationships. The fungus must not only survive but also work effectively in synergy with your usual helpers, without dying from accidental contact with incompatible chemicals. Below, we examine the key rules for creating tank mixtures and the specifics of seasonal application of the preparation.

4.1. Companions and Compatibility: What to Mix With (Phytosporin, Senna Stick) and What Not to Mix With

The success of applying trichoderma in the greenhouse directly depends on its correct combination with other preparations. This soil fungal antagonist gets along very well with many beneficial bacteria, but it is extremely sensitive to chemical fungicides.

Ideal Companions (What can be mixed):

Senna Stick (Bacillus subtilis, including Phytosporin): This is a classic and very effective tandem. The bacterium and the green hypocreal fungus do not compete for food resources. Senna Stick works quickly on the leaf surface and in the top layer of the soil, suppressing pathogens, while trichoderma actively colonizes the root zone (rhizosphere) and decomposes organic matter. Their combined working solution doubles the protection against late blight and root rots.
Humates and Nitrogen-Fixing Bacteria: Serve as excellent starting nutrition and stimulate mycelial growth.

What must not be mixed:

Chemical Fungicides: Any copper-containing preparations (Bordeaux mixture, HOM, Abiga-Pic) and systemic chemical fungicides completely destroy the living biocontrol agent. The interval between their application and the application of trichoderma must be at least 10–14 days.

4.2. Seasonal Practices: Treating the Greenhouse in Autumn and Spring for Long-Term Protection

Seasonal greenhouse treatments are not a one-time event but a comprehensive cycle that ensures long-term protection and soil health. Trichoderma, as a soil antagonist fungus, works not only at the time of watering but also accumulates colonies in the substrate, creating a constant protective background. Therefore, it is important to conduct preventive treatments at key periods of the year.

Spring Start: Preparing for Active Growth

Spring is a time of awakening and maximum vulnerability for seedlings. The main task is not only to destroy overwintering pathogens (such as late blight pathogens) but also to activate the soil microbiome.

When: 1–2 weeks before transplanting seedlings or sowing seeds.
How: Perform a thorough watering of the root zone and apply the preparation into the planting holes. This "wakes up" the mycelium, allowing it to occupy optimal niches before the first sprouts appear.
Additionally: During this period, Trichoderma can be used in combination with immune-boosting preparations (such as root stimulants) to ensure maximum effect from the "awakening."

Autumn "Hardening": Preparing for Winter Dormancy

In autumn, the greenhouse goes through a period of reduced activity and pathogen accumulation. The goal of the treatment is not only to suppress diseases but also to provide the mycelium with nourishment for winter and to prepare the soil for the next season.

When: At the end of the growing season, after harvesting the main crop, but before severe frosts set in.
How: Perform deep watering and apply the preparation across the entire greenhouse area. This helps the mycelium "settle" into the substrate and prepare for wintering.
Important: Be sure to cover the beds with agrotextile or mulch them with organic matter. This will retain moisture and provide the mycelium with nutritious residues, which is critical for maintaining the colony throughout the winter. This approach ensures that in spring, the fungus will be ready for active work, without expending energy on survival, but immediately starting the fight against pathogens.

Section 5: Safety and Optimization — Your Actions Before, During, and After Treatment

We have thoroughly covered how to prepare the ideal mother solution and studied the methods for applying trichoderma to both seedlings and established soil. However, even the highest quality bio-preparation requires proper handling and consideration of external factors. The effectiveness of trichoderma depends not only on the dosage but also on the conditions in which it is used: from water quality to adherence to personal safety measures. In this section, we will solidify the knowledge on how to minimize risks, avoid common mistakes, and ensure maximum protection for your greenhouse throughout the season.

5.1. Technical Liquids and pH: How to Prepare Water and Soil for Work

The effectiveness of trichoderma directly depends on the quality of the water and the condition of the soil. For the beneficial fungus to activate rather than die during watering, observe three key rules:

Water Quality and Temperature. Never use chlorinated tap water—chlorine is harmful to microflora. Use rainwater, melted snow, or let tap water settle for at least one day. The working solution temperature must be within +18...+25 °C. Cold water reduces spore mobility.
Water Acidity (pH). The optimal range for trichoderma is pH 5.5–6.5. If the pH is above 7, the fungus's activity drops sharply, and at a pH below 5, the spores lose viability.
Soil Condition. The antagonist fungus develops successfully in soil with an acidity of 5.5 to 8.5 pH. Before applying the preparation, ensure the soil is moderately moist, as the mycelium cannot spread in dry soil.

5.2. Myths and Dangers: Common Beginner Mistakes and Precautions

There are many dangerous misconceptions surrounding the use of trichoderma that can negate all efforts or harm health.

Main Mistakes and Myths:

Mixing with chemical fungicides. Simultaneous application of trichoderma and chemical fungicides (especially copper-containing ones) completely destroys the beneficial mycelium.
Applying to dry soil in the sun. Without moisture, spores will not germinate, and UV radiation is harmful to them. Perform the treatment in the evening or on a cloudy day.
Expecting instant results. The fungus requires 14 to 30 days to colonize the substrate and displace pathogens.

Precautions:
Dry trichoderma spores are a strong airborne allergen. When preparing a powder solution and spraying, always use a respirator and gloves to avoid inhaling microspores.

Reference Checklist: Brief Seasonal Treatment Plan

A convenient seasonal plan guide for maintaining trichoderma activity in the greenhouse:

Early Spring (2 weeks before planting): Soil revitalization. Water the beds with a warm trichoderma working solution at a soil temperature of +12 °C.
Seedling Transplanting: Apply the preparation into the planting holes (e.g., a tablet of "Gliocladium" or 100 ml of liquid mother solution per plant).
Summer (Vegetation, every 14–20 days): Preventive watering at the root and foliar spraying to protect against late blight and rots. Compatible with Senna Bacillus.
Autumn (After harvest): Thorough treatment of the soil and plant residues to accelerate their decomposition and destroy overwintering pathogens.