Growing tomatoes in advance: Here’s how it’s easy

Last updated on October 23rd, 2023 at 08:16 pm

Growing your own tomato plants from seed is not that difficult if you know the needs of the little seedlings and young plants and care for them. Tomatoes do not need it quite as warm and also germinate faster than peppers and chilies – if you still want to sow these peppery fellows, you still have until mid-March to do so.

Everything at a glance

 Sowing
indoors
Germ-
temperature
Temperature
After germination
PrickingPlanting out
TomatoesBeginning of March
till the end of April
20 – 25 degrees18 – 20 degreesfor two foliage leavesMiddle May

Growing tomatoes in advance: Here's how it's easy

The right time

Sowing tomatoes can also start as early as the end of February, but since the seeds germinate quite quickly and the seedlings then need a lot of light, sowing is recommended from the beginning or middle of March. Pre-planting indoors is still possible until the end of April – after that it makes more sense to sow the tomatoes directly from mid-May. Seedlings sown indoors between late April and mid-May are still super small at the ideal time for planting (mid-May), if they have germinated at all. Tomatoes sown directly outdoors from mid-May onward will quickly catch up with this small growth advantage, so preplanting won’t be worth it by then. You can still direct seed tomatoes outdoors until about mid-June, but it’s better to do it sooner than later so the plants still have plenty of time to produce lots of fruit.


The right growing pots

Tomato seeds, depending on the variety, are reasonably large and easy to handle. Different numbers of seeds are sown depending on the size of the pot. In this photo you can see pots with a size of 5 x 5 cm. In each pot we put only one seed:

Growing tomatoes in advance: Here's how it's easy

A standard size for slightly larger, round pots is about 10 – 12 cm, in which you can also sow 2 – 4 seeds. With more seeds, potting will be more difficult later, because the small roots can grow together and you have to be careful not to crush the other plants in the pot.

Quick homemade are upcycling pots from old Tetrapak packaging. Simply cut them off at the desired height, clean them and possibly poke a few holes or cracks in the bottom. But even without drainage, the cultivation succeeds if you water sparingly.

Growing tomatoes in advance: Here's how it's easy
There are also growing pots made of compostable material – here with bell pepper seeds

The right soil

Use special growing soil for sowing, often also called herb soil. This is particularly low in nutrients. Too many nutrients would stimulate the small seedlings to grow much too rapidly: they would shoot up long and sparse. But we want the roots to develop vigorously in search of nourishment.

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Growing soil can also be mixed yourself with a little effort, but this is more something for people with a garden. As a basis for this is best suited loose garden soil, which is conveniently often dug up for us by moles, especially in the spring. This is mixed in equal parts with sand and compost. As compost soil, for example, soil from the leaf compost is very suitable, but you need to create it in time in the fall. Alternatively, you can buy compost in smaller quantities in bags.

Garden and compost soil can be sterilized at 120 degrees for about 30 minutes, so that other seeds contained in it can no longer germinate. However, heat treatment in an oven or microwave will also kill any small soil inhabitants. Alternatively, the soil can be sieved (first) to remove seeds, small stones or bugs.

For old soil that has been overwintered outside in a bag or comes from previously planted containers, sterilization is more advisable to eliminate pathogens such as fungi or small pests. These can quickly kill off young seedlings.


The right sowing

Tomato seeds can be soaked in warm water before sowing. This works well overnight and speeds up germination a bit. If you want to get started right away, this is of course possible without soaking.

Fill the soil into your seed pots. You can leave some air on top, place the seeds on the moistened soil and cover them with a layer of soil about 0.5 – 1 cm thick. Or you can simply press the seeds with your finger deep into the already full pots and cover the resulting holes with soil again.

In any case, the soil can now be moistened again well, this works best with a spray bottle.

If you want, you can cover the pots with foil or put them in transparent plastic bags. This will create a greenhouse climate and the soil will stay moist longer. Otherwise, the soil will dry out quickly, as the seeds like to have it very warm for germination. Temperatures of 20 to 25 degrees are ideal.


The right location

Place the seed pots in a bright and warm place. Near a heater is ideal. After 7 days you may already see the first tender green growing out of the soil, but it can take up to 14 days. When all seeds have germinated, you can move the pots to a cooler place or turn down the heat. 18 – 20 degrees are now more than sufficient and especially important is the light. The young seedlings should get the brightest place you can find. If they are too warm or dark, they will die. That is, in search of light and stimulated by the temperatures, they become quite thin, long and unstable.

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Growing tomatoes in advance: Here's how it's easy
A bright place in front of a window, preferably facing south, is perfect

The pricking

In a nutshell:

  • Prick out the plantlets when they have their first pair of deciduous leaves.
  • Place them in more nutrient-rich soil and give them more space.
  • Plant them about 1 – 2 cm deeper.

First the so-called cotyledons appear on the plantlets. These always look a little different than the later leaves. After about three to four weeks, most of the plants should have developed a first pair of leaves, which means it is time for pricking out. This means that the plants are transferred to larger pots. However, it is also possible to keep the size of about 10 – 12 cm, but give each plant its own pot. In our example with the smaller growing pots, it is necessary to use larger vessels.

Tomatoes like to be pricked out twice. If you want to prick them only once (which also works), wait until they have developed four leaves instead of two.

The first thing you can do is prepare the new pots. First, fill them completely with soil. Do not use pure growing soil anymore, but mix it with nutrient-rich potting soil. If you mix your own soil, you can reduce the amount of sand or increase the amount of compost. Drill a hole in the center with a pricking tool of your choice (more on this in a moment).

Now move the plants. They are very delicate and must be removed from the soil very carefully. Under no circumstances should you pull on them! What you use for pricking out is a matter of taste. There are special pricking sticks that fit well in the hand. However, thick knitting needles or even chopsticks work similarly well. Flat handles of teaspoons are also suitable, or even a spoon itself. Depending on how big your growing pot is and how dense the plantlets are in it.

The best way is a kind of lever technique: Loosen the soil carefully and place the tool of your choice at some distance from the plant to lever it out of the pot together with the soil. If you pry too closely into the soil, there is a great risk that you will injure the roots.

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Growing tomatoes in advance: Here's how it's easy
With the help of the pricking stick here is prepared a hole for the plant

You can now place the plant about 1 – 2 cm deeper in the new soil than it was growing before. Tomatoes, just like bell pepper plants, can also form roots on the stems when they are in contact with the soil. Thus, the young plant becomes more stable.

You may wonder if it’s even necessary to prick out the plants, but instead just use larger pots right away. This is a good idea in itself, but not for tomatoes. These benefit greatly from being set deeper and having more nutrients available in the new pot. They are heavy growers and would not grow vigorously enough to last the time until planting out otherwise.

Squash and zucchini are also heavy growers, but are not necessarily pricked out. This is not a contradiction, because the cucurbits are sown only from the beginning of April – so their time in the pot is much shorter than tomato, bell pepper & Co.

The time until planting

Congratulations: you have done a good job and successfully raised many seedlings. Your tomatoes are no longer in their infancy, but have already made their first move and are getting bigger every day. Slowly it is time to think about their final move out. In order for them to cope well, you can put them out into the fresh air for a few hours during the day in good weather from mid-April onwards. Very important: It should be at least 15 degrees and the location should be protected from the wind and bright, but not sunny. The wind and strong, unfiltered sunlight are unfamiliar and can damage the delicate leaves.

However, this hardening off is a super thing and will make your plants even hardier. Also, if you don’t have that much time, you can still put them out for an hour in the late afternoon, for example.

In mid-May, the danger of frosty nights is finally over and the big move is on.

Author

  • James Jones

    Meet James Jones, a passionate gardening writer whose words bloom with the wisdom of an experienced horticulturist. With a deep-rooted love for all things green, James has dedicated his life to sharing the art and science of gardening with the world. James's words have found their way into countless publications, and his gardening insights have inspired a new generation of green thumbs. His commitment to sustainability and environmental stewardship shines through in every article he crafts.

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