A vegetable garden in a greenhouse is a useful addition to the outdoor garden. Greenhouses can be used with advantages for various gardening activities. Sensitive plants are grown in it, or vegetables are grown at a time when outdoor weather conditions are less suitable for this. We can choose from many shapes, sizes, and materials, and there is sure to be a combination that suits our needs. The greenhouse will open up entirely new possibilities for growing garden plants. Its most significant advantage is that we will be able to grow and enjoy the produce, even when it is no longer possible to do so outdoors due to the weather.
Experienced grower Klaus Laitenberger shows in the book “Vegetables and Herbs for the Greenhouse and Polytunnel” how to use the shelter and heat of a greenhouse or polytunnel to make a large crop production and supply tasty, healthy food throughout the year.
Space for a Vegetable Garden in a Greenhouse
When choosing a suitable place for a greenhouse, we must consider all the factors that could influence the right decision. An open, leeward, and sufficiently bright place is the most suitable for setting up a greenhouse. This can also be next to a building, but the location should be at least partially shaded so that the greenhouse does not get too hot on hot days despite good ventilation and shading. However, it should not be in the shade for more than a few hours daily. Regarding the utilization of daylight, the direction of installation is also essential. The summer light will be best utilized if the greenhouse is placed on the longer side in the north-south direction, and for cultivation in winter and spring, when the sun is low, the east-west direction is more suitable.
Types of Greenhouses
Considering the price is the main factor in setting up greenhouses, they can be divided into more expensive and cheaper ones. The first ones are made of the best materials and are like glass houses, in which the conditions are excellent for growing even the most demanding plants. With such greenhouses, appearance is also essential, not only practicality, so they are usually part of a decorative garden, and primarily ornamental plants get a place in them. In addition to glass, plastic materials are also used, which have some advantages over the glass but are generally less permeable to light. The frame itself is usually made of wood, aluminum, or steel. Wooden is the most beautiful, while aluminum and steel are more practical and thinner, so more light passes into the interior.
The Practicality of the Vegetable Garden in a Greenhouse
For the most part, gardeners are more interested in the practicality of the greenhouse than in its appearance, which means that it can be easily assembled and disassembled when it is no longer needed. Including a greenhouse in the garden has many advantages, but above all, vegetables can be grown earlier and enjoyed all year round. You don’t have to wait too long in the spring and be in fear that your vegetables will freeze. If we think of the simplest and unheated greenhouse, we grow the seedlings in a warm room, as they need suitable conditions for germination and development, and then we transplant them into the greenhouse. Due to earlier planting, the harvest is also earlier and can be harvested long after the outdoor beds have already been abandoned. It is also essential for greenhouses to be durable enough not to break under the weight of snow or topple over due to strong winds. Lightweight modular ones are also efficient, as they can be assembled on a different garden bed each time, thus taking into account the cycle in the best possible way. They are handy for producing more demanding vegetables, such as tomatoes, which are often affected by potato mold outdoors, but in the greenhouse, the problem with this disease is negligible.
Filling the Beds in the Greenhouse
Due to the small space size, it must be planned appropriately so that the greenhouse is used to the best advantage. Winter salads, radicchio, cruciferous vegetables, and other lettuce will grow beautifully in them, and these can be followed by fruit crops such as peppers, tomatoes, and eggplants. A few winter salad plants can be left on the beds outdoors under the gardening cloth. And when the crop in the greenhouse has grown and we have planted the area in it with fruiting vegetables, the salad boxes outside will be just suitable for use.
The Heating of Greenhouse
Heating the greenhouse is essential and depends on the plants grown in it. The most convenient are electric heaters, which are also the most reliable and efficient and do not emit harmful vapors into the atmosphere, and in summer, they are also used to cool the room.
Unheated Greenhouses
Even though they do not have additional heating, we will grow and harvest crops in them all year round. Sensitive tropical plants have nothing to look for here. Still, the growing conditions will be satisfactory for producing vegetables, such as fruiting vegetables from spring to late autumn and hardier salad plants and other vegetables during the winter cold.
Ventilation in the Greenhouse
Greenhouse ventilation is important for plant growth, as it regulates the internal temperature and humidity and reduces the concentration of various gases. We can choose from many ventilation systems and adapt them to the size of the room. Suction fans are similar to the ones we have in the kitchen and work great in larger greenhouses. It is only necessary to correctly assess the size of the room and choose a sufficiently powerful fan. In the smaller greenhouse, we will ensure ventilation by opening the upper windows and hatches. Ventilation windows at the top of the greenhouse are suitable for summertime, but in winter, flaps that are placed lower are better.
Shading
In addition to ventilation, the temperature in the greenhouse is also controlled by shading. This is especially important in summer when the sun is high, and the plants must be protected from heat and burns. Shades are installed on the outside, as their effect is much worse on the inside, and the intensity of shading depends on the season and plants; cacti need almost no shading, while most other plants should shade around fifty percent of the surface through which light passes.
Irrigation
Due to the closedness of the space, the plants in the greenhouse are entirely dependent on our water supply. In the small one, we will be able to do everything manually with watering, but in the larger one, an irrigation system must be installed, which comes in handy even in our absence. The drip irrigation system is the most widespread way of supplying plants with water in greenhouses. It consists of pipes with many nozzles routed to the plants. At the same time as irrigation, we can fertilize by adding a suitable liquid fertilizer. Since the needs are constantly changing, we must continually control the amount and adjust it to the needs of the plants.
Preparation of Beds
The beds in the greenhouse can be permanent, but plants can also be grown in containers or growing bags; smaller greenhouses can be moved to another bed, etc. It is important to provide plants with good growing conditions. Vegetables need at least a 30 cm thick layer of soil, while 10 to 15 cm will be enough to grow seedlings. The soil in the greenhouse is cultivated shallowly, and organic fertilizers such as compost and stable manure are added (a mixture of horse and cow manure in a ratio of 1:1 is best). After raking, the surface is covered with horticultural fabric for ten days to allow the weeds to emerge, after which the cover is removed. The weeds are also removed with minimal intervention in the growing area. Then vegetables and ornamental plants are sown and planted.