Sowing tomato seeds is easier than you think. Find out all the important steps here so that you can do it successfully behind glass. So the project has a good star right from the start.
What is the best way to sow tomatoes?
Tomato seeds are soaked in lukewarm chamomile tea or diluted garlic juice before sowing. Then you sow them individually in cultivation pots, cover them 0.5 cm high with seed soil and moisten them. Growing behind glass at 18-24°C and sufficient light is ideal.
This pretreatment improves the germination of tomato seeds
The 2-3 millimeter small tomato seeds signal a natural inhibition of germination with their velvety, slightly hairy shell. Before you sow the seeds, it is advisable to stimulate germination.
- Soak tomato seeds in lukewarm chamomile tea for 6 hours
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alternatively place in garlic juice diluted 1:10 at room temperature
Of course, normal tap water is also suitable for pre-treatment. The advantage of the solutions mentioned is the simultaneous prevention of mold formation, which is probably the greatest danger when sowing.
Early sowing behind glass – these steps are key
Regardless of whether you want to cultivate your favorite tomato varieties in a bed or in a container, growing them behind glass is recommended. The best time to start sowing is the end of February/beginning of March. Ideally, a light-flooded winter garden, a bright greenhouse or a spacious windowsill are available.
- Fill cultivation pots or a seed tray two-thirds full with standard sowing soil, coconut fiber, perlite or peat sand
- Sow tomato seeds individually at a distance of 3 centimeters
- fill the seed container with substrate so that the dark germinators are covered by 0.5 centimeters
- moisten the sowing with water from the hand sprayer
An exemplary germination temperature fluctuates between 18 and 24 degrees Celsius. If you keep the growing medium slightly moist at all times, you can look forward to the first seedlings after 10 to 14 days. During this phase, create a warm, humid microclimate on the windowsill, for example with the help of a heated mini greenhouse. Alternatively, simply stretch cling film over each cultivation container.
Compensate for poor lighting conditions
A central factor in growing tomatoes is the lighting conditions. Experience has shown that it is bright enough in the winter garden or greenhouse. On the windowsill, special plant lamps (€79.00 on Amazon) improve the light supply during cultivation. Otherwise, the plants will stretch towards the sun, which will inevitably cause them to rot and fall over. For this reason, we recommend sowing on the windowsill from mid-March at the earliest.
If you then place a mirror behind the seed container, the light-hungry tomato seedlings should no longer go looking for light. Rather, they then adopt the desired compact habitus.
All important steps until planting out
If the conditions are right, the first, tender cotyledons will appear after 2 weeks. Now development is taking place quickly, while the warm, humid climate continues to be maintained. The ventilation flaps in the winter garden or greenhouse should be opened for a few minutes every day. In addition, the substrate and the seedlings must not dry out under any circumstances. As soon as at least one additional pair of leaves has developed above the cotyledons, the time is ripe for pricking out. Here's how to do it:
- Pour compost-based vegetable soil into 9 cm pots and moisten
- lift the strongest seedlings out of the substrate using a pricking rod
- shorten very long root strands with scissors to a length of 2 centimeters
- drill small planting holes with the pricking rod
- place each tomato plant in the soil up to the base of the leaves
- press the substrate and moisten it with a fine spray
Water the tomato plants moderately but regularly. There is no fertilization in this phase of growth. By mid-May the tomatoes have reached a height of around 30 centimeters. Once the ice saints have said goodbye, they are planted out in the bed or in the bucket.
Does direct sowing make sense?
In our latitudes, a tight window of opportunity opens up every year for growing tomatoes outdoors. Direct sowing should not be considered until mid-May at the earliest. In order for the tomatoes to ripen by autumn, good to optimal weather conditions are required. Before you give up on growing tomatoes yourself, it's worth a try with the following precautionary measures.
Choose a sunny, sheltered location. A place in front of the south wall of the house is ideal, ideally under a canopy. Offer heavy feeders nutrient-rich, humus-rich, fresh soil. Protect the seeds with a polytunnel. As a result, you build a tomato roof as protection from the rain. When sowing, proceed as follows:
- weed the bed soil thoroughly and remove roots
- Work garden compost, horn shavings or horn meal into the soil
- Draw a seed trench and sow the tomato seeds in it
- sieve thinly with soil and moisten carefully
- Pricking starts from the second real pair of leaves
Tips & Tricks
The mildly spicy tomato aroma develops even more intensely if garlic broth is used for the watering from the start. To do this, let two cloves of garlic steep in 10 liters of water for 12 hours. Every 14 days, this solution replaces the irrigation water for one pass.
