Tomatoes are the most greenhouse-grown vegetables on the planet. By paying attention to temperatures and ensuring plenty of light, farmers can get two crops of tomatoes per year. Indoor cultivation requires more care and attention, both to avoid disease and to be able to pollinate the flowers successfully.
Steps
Part 1 of 3: Set up
Step 1. Check the temperature
Tomatoes grow best with daytime temperatures of 21-27 ° C and night temperatures of 16-18 ° C. Be sure to maintain such conditions in the greenhouse for several months before deciding to grow your own plants.
- The ideal would be to keep the minimum values on cloudy days and reach the maximum values (or even slightly higher) on clear and sunny days.
- You also need to ensure a humidity of less than 90%, to prevent the leaves from becoming excessively moldy. Provides regular ventilation by letting dry, cool air into the greenhouse, especially on cold, cloudy mornings.
Step 2. Choose the tomato variety
There are hundreds of cultivars of this plant, so you should contact some local grower for more information. However, here are some general guidelines and advice that apply to all climatic regions:
- Varieties specifically indicated for greenhouse cultivation tolerate indoor conditions better;
- The letters VFNT on the package indicate that the variety is resistant to diseases;
- Indeterminate tomato plants grow and bear fruit continuously, offering the advantage of a longer growing season inside the greenhouse. If you have limited space, you should grow the "determined" variety, which does not exceed a certain height.
Step 3. Choose the soil for planting
Tomatoes can grow on any well-draining substrate; you can decide to use an earthless mix or opt for one of these solutions:
- In many areas the cheapest options are represented by bags of perlite or pieces of stone wool;
- Some growers prefer to use a mixture of equal parts sphagnum peat and vermiculite;
- Purchase a sterile potting mix or make your own. Never use soil or garden compost without first sterilizing it. Choose this option if you don't want to install an irrigation system.
Step 4. Install an irrigation system (recommended)
Most growers install drip hoses to supply each individual plant with water; it is also possible to add a fertilizer injector to fertilize automatically.
Tomatoes also grow well with a hydroponic system; read this article for detailed instructions
Part 2 of 3: Planting Tomatoes
Step 1. Fill a germination tray with potting mix
Wash the container thoroughly with soap and water to disinfect it and fill it with any of the substrate solutions described above.
- If you use the earth, make sure it is sterilized.
- If you opt for a soil-less mixture, you need a nutrient solution for the seedlings (read below).
Step 2. Plant each seed in the individual tray
Make a small 6mm notch in each compartment of the tray, insert only one seed in each space and cover it lightly with potting soil.
Plant about 10 to 15 percent more of the seeds you want to grow, so you can discard the less healthy seedlings
Step 3. Wet lightly with water or a diluted nutrient solution
If you put earth, plain water is fine; if you have chosen a soilless mixture, water with a nutrient solution. Either way, wet the seedlings until the potting soil is moist enough to allow you to squeeze out just a few drops when you squeeze a handful. Water regularly to keep the soil moist.
The ideal is to use a 5: 2: 5 nutrient solution containing calcium and magnesium; dilute it following the directions on the package
Step 4. Keep the tray on a warm windowsill
You don't have to put the seeds in the greenhouse until the seedlings have sprouted, so you can check if they get sick or are plagued by pests. Make sure they are adequately exposed to sunlight and maintain a temperature of around 24-27 ° C in the room during the day.
To keep the temperature under control, you need to partially expose the tray to the sun; put it in direct light only when all the seedlings have sprouted; generally, it takes 5-12 days
Step 5. Transfer them to larger containers
About two weeks after germination, place them in small pots inside the greenhouse. After 6 or 8 weeks, when the seedlings are about 10-15 cm tall, you need to transfer them to larger pots or bags. Each seedling needs about 0.02 m on average3 or even less of potting material (14-28 liters). Keep in mind that even the smaller varieties produce less fruit when grown in smaller pots.
- If you see any bugs, mold or diseased areas on a plant, don't take it to the greenhouse.
- Give each plant a space of about 0.4m2; if you bury them too close to each other, you restrict air circulation and encourage the development of some diseases.
Step 6. Adjust the pH and calcium levels
Before the last transfer, you must check the pH of the soil, which in theory should be between the values 5, 8 and 6, 8. If the soil is too acidic, add about 5 ml of hydrated lime (or slaked lime) for each 4 liters of mixture for the filling; in addition to increasing the pH, this substance also prevents the flowering from rotting later.
- If the pH is within the correct levels, add a mixture of chalk or calcium sulfate instead of calcium, without altering the pH values. Alternatively, you can simply choose a fertilizer containing calcium and apply it every week or two.
- If you have created a hydroponic system, you can provide calcium by injecting calcium nitrate into the fuel system; in this case, however, a second injector is required, because the calcium nitrate cannot be stored with the main fertilizer.
Part 3 of 3: Caring for Plants
Step 1. Fertilize regularly
Start fertilizing the day you transfer the tomatoes to the final pot. Use a complete product, rich in nitrogen (N) and potassium (K), for example a blend with a 15-5-15 or 5-2-5 ratio. Dilute the fertilizer and apply it according to the directions on the package.
Reduce the amount of fertilizer as the fruit ripens. Don't apply it in late fall or winter unless you use artificial grow lights and reliable heaters
Step 2. Remove the suckers every week
Once a week pinch the suckers or side shoots that appear in the area where the leaves join the stem. Leave only the main shoot on the apical part of the stem, as well as the tallest sucker immediately below, to allow the plant to grow upwards, rather than in width.
If the top tip of the plant is damaged, the top sucker can begin to develop a new main stem
Step 3. Stake the tomato plants
Tie the plants loosely to stakes using a string to keep them straight. Use plastic garden clips where the twine needs to be clamped.
Commercial crops save on material by spreading an iron wire over each row, with a support pole every 6 m. Wrap the string around each plant and attach the top end to the wire above
Step 4. Pollinate the flowers
Unlike many other plants, the tomato can pollinate itself, but it needs some help. The pollen from the flower is trapped inside a small tube and is released through vibrations. Since there are no bees in most greenhouses and there is not much wind, you need to pollinate yourself once the flowers have fully opened:
- For best results, purchase an electric vibration pollinator. Place the tool on the stem of each flower every other day at a time between 10:00 and 14:00 (an alternative solution is an electric toothbrush, although less effective).
- To save time, you can use a nebulizer, directing the puff towards each cluster of flowers.
- If you have a large farm, consider keeping your own bees.
- As a last resort, you can try to gently shake each individual stalk; however, keep in mind that this method involves a high risk of damage to the plant.
Step 5. Thin out the leaves and fruits
In addition to removing the suckers every week, there is no need to prune the plants until the fruit begins to form:
- When the tomatoes start to grow, thin out each bunch leaving only 4 or 5 fruits and removing the smaller or deformed ones. If the fruits are very large or you are in the winter season, you should keep no more than three fruits; if you are growing a variety that produces small tomatoes, no thinning work is required.
- As the fruit ripens, tear off the older leaves from the lower clusters to improve air circulation.
Step 6. Reap the rewards as late as possible
The longer they stay on the plant, the more red and pulpy they become. Those who grow tomatoes for commercial purposes usually harvest them when they are at 60-90% of ripeness, to allow them time to turn completely red during transport.
Advice
- While you can harvest the seeds for planting the following year, keep in mind that they are no longer part of the original variety. The new generation always takes on a different appearance or flavor and may not even grow in the same climatic conditions; it could also carry diseases and infect the "mother" plant.
- Commercial growers should send a soil sample to the laboratory for detailed analysis; in this way it is possible to assess exactly which nutrients are needed.
- Unless you're planting them in the winter, greenhouse tomatoes will get all the sun they need. You can install lamps to speed up the growing process and extend the "day" for up to 16 hours, but be aware that this is an expensive method. If you grow tomatoes for profit, it is worth using HID or gas discharge lamps if you plan to get a winter harvest, but only if you are selling locally and your customers are willing to spend more to eat tomatoes in the winter.. Those who grow these fruits for passion can choose cheaper fluorescent lamps if other light than natural is needed.
Warnings
- Always check plants for pests. If you don't inspect any that grow indoors, the insects can develop quickly and eventually you are no longer able to keep them under control. Diatomaceous earth can be a solution to aphids and whiteflies.
- Be careful when removing the suckers; if you accidentally remove the main stem, you can cut fruit production by half.
