Organic Gardening in a Greenhouse

Using greenhouses noticeably shortens the time to harvest vegetables. This is an undeniable advantage of greenhouse farming. At the same time, gardeners often complain that after a couple of seasons, vegetable yields noticeably decline. This may be due to soil exhaustion. The reason is that within a single greenhouse, in a closed space, the soil quickly "tires". Those who are advocates of organic gardening are thinking about solving this problem.

Temperature Regime

There is a biological temperature maximum and minimum, beyond which plants cannot survive and die. For protected soil, agronomic critical values are used, when the plant does not die. For cucumbers, this indicator equals 8-9 degrees. For comparison, the biological minimum is about 0.6 degrees.

Pollen of some tomato varieties becomes sterile at 30-degree temperature. At 35 degrees, regardless of variety, tomatoes stop forming fruit. All this indicates that in a greenhouse, you need to carefully monitor the temperature regime, including maintaining warmth, and preventing overheating.

Heat Reserve

In cold seasons, the greenhouse "operates" at 15-25-degree temperature inside. Such a temperature regime is achieved by different ways of accumulating and retaining heat. An alternative is heating the space. It is important to consider where most of the solar energy comes from. What do organic gardening advocates recommend here?

The transparent northern side of the greenhouse (traditional variant) does not participate in heating due to rapid cooling. Therefore, it is better to choose a heat-retaining material for this wall. This can be stone or brick. Some place barrels filled with water along the northern wall and insulate them from the inside. In this case, barrels serve as heat accumulators. The larger they are, the slower the temperature in the greenhouse drops. Insulation retains internal heat. You can arrange barrels with water and insulate the northern wall at any stage of greenhouse operation.

Tip: if you have a poultry house, build the greenhouse so that its northern wall adjoins the agricultural structure. By the way, the poultry house will "share" heat with the greenhouse.

Regarding heated greenhouses, it is better to equip them with a "warm floor" at a depth of no less than 50 cm. With such a structural solution, the soil heats up and cools down more slowly, and maintains an optimal microclimate for plants.

To Avoid Overheating

Excess heat in the greenhouse during summer leads to overheating and burning of vegetables.

Important: sunlight before noon is less harmful than in the afternoon and evening.

Light-shielding coverings — these are various blinds (non-woven fabric, dense mesh, or others) in rows, tarps over the greenhouse made of low-light-transmitting materials (camouflage net), latticed pergolas. Glass greenhouses are whitewashed with lime to reduce light intensity.

Ventilation

This is another way to prevent overheating.

In modern factory greenhouses, for example, made of polycarbonate, ventilation is provided by through doors at the ends. Such ventilation harms plants. First, warm air exits the greenhouse not above the door level, but hot air accumulates under the ridge. Second, air exits only from areas near the door, while in the middle section, heating remains intense. Third, due to intensive evaporation of moisture by plants, they quickly dry out.

Ventilation is organized under the ridge, with windows opening from the ridge. Since ventilation must be conducted regularly when temperature exceeds 25-27 degrees, a special thermal automatic device for opening windows will be useful. Check out fully equipped greenhouses https://gtconcept.com.ua/greenhouses.html

Reviving Exhausted Soil

When growing the same crop in a greenhouse, yield decreases each year. This phenomenon is called "soil fatigue" and occurs for several reasons:

• release of organic compounds by higher plants that negatively affect other plants;
• extraction of nutrients, minerals, and microelements from the soil suitable for this type of plant;
• increase in concentration of pests and pathogens that attack this (or similar) plant type.

In such a case, the lifeboat is crop rotation. Organizing it in a greenhouse is not a simple task. Experienced gardeners grow companion crops until planting the main crops.

From mid-February, in heated greenhouses, leafy crops are grown, and onion seedlings are planted for green onions.

In unheated greenhouses, from the end of March, salad and cruciferous crops are sown, and seedlings of cabbage and some other cold-tolerant varieties are planted.

To prevent seedlings from dying from night frosts, they are additionally covered with non-woven fabric or covered with individual caps made from available materials.

Crop rotation in a greenhouse can replace full or partial soil replacement. In the second case, in each hole with a diameter of 35-45 cm and a depth of about 40 cm, half a bucket of compost and fresh soil are added until full. Full replacement means moving soil from beds to the garden and bringing new soil into the greenhouse.

Warm beds as a soil enriching strategy for greenhouses

The strategy for creating a warm bed is simple. In a trench dug to a depth of two to three shovels, organic matter is laid: leaves, straw, plant tops, grass, remnants of plant food. Some greenhouse owners add biologically active preparations (e.g., Baikal) or preparations made from them, and thoroughly moisten this organic matter. After the start of decomposition in this warmed mass, holes are made and seedlings are planted. By autumn, the organic matter in such beds fully decomposes into compost, which can be transferred to the garden, and organic matter is stored in the trenches for the next season.

Cover Crops to the Rescue

In late autumn, a few weeks before the end of the season, rye, oats, rapeseed, or mustard are sown in the rows. These plants are cut and incorporated into the soil. In spring, cover crops are sown before main crops, cut, and used as mulch for beds. Mustard seeds germinate at 1-2-degree temperature, and sufficient green mass is obtained within a month.

By the way, the aforementioned methods of combating reduced vegetable yields positively affect soil structure and humus content.

One of the main goals pursued in organic farming is maintaining beneficial microflora for plants in the soil. For this, biologically active preparations with microbes are used.

Important: simple application of preparations does not ensure the desired result. They are effective only when used together with aeration, measures aimed at protecting the soil from overheating and drying out.

Towards High Yields!

Soil fertility in greenhouses improves after applying local organic fertilizers (manure, compost, herbal infusions).

Important: fresh manure is aggressive due to nitrogen present in it. If you overuse such fertilizer, you may lose all your plants.

Compost is applied both in individual holes for each plant and over the entire bed area. Good results are achieved by mulching with mown cover crops. Also effective is watering once a week with herbal infusions with a small amount of bio-preparations.

To prevent fungal diseases, regular treatment of plants with the preparation Phytosporin is necessary. Against aphids and other pests, you can use Fitoverm or analogs. Do not overcrowd plantings in the greenhouse, as weak air movement creates a microclimate suitable for the development of pathogenic microorganisms. In addition, under heavy crowding, it is harder to detect pest appearance. To prevent phytophthora, it is desirable to sow mustard early in spring as a cover crop: it binds soil iron and thus hinders the development of phytophthora.

Do not forget to use wood charcoal. It has a large surface area for absorption, and beneficial microorganisms settle on it. Also, due to porosity, soil air and water exchange improves, nutrients are adsorbed and do not leach into lower soil layers, from which plants find it harder to extract them. Another advantage: weeds grow worse on soil enriched with wood charcoal.

You can also use preparations based on trichoderma — a soil fungus. They allow you to combat phytophthora, powdery mildew, gray and white rot, black leg, leaf curl, and many other diseases. The principle of action is based on parasitism of the trichoderma mycelium on mycelium of other fungi. They can be applied to seeds before planting, holes into which seedlings are planted, or to disinfect beds before the start of the season. Additional beneficial effect — the preparations help decompose organic matter into compounds easily absorbed by plants, i.e., fertilize the beds.