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6 Tips For Growing Great Tomatoes

30 March 2021

Growing tomatoes does not have to be hard or take that much time - and you do not need a greenhouse or a garden. You can cultivate potted tomatoes from a window or on a balcony. To be able to enjoy a ripe tomato, warm from the sun, right from its plant is incredible! Would you like to try growing your own tomato plant from a seed? 

1. Choose tomato varieties based on the space you have 

Growing tomatoes does not have to take up that much space if you choose seeds based on your space. If you have a limited amount of space, Bitonto or Tiny Tim are two good choices. They can be grown by a window or on a balcony, even when they have grown to full-size tomato plants. Romello is also a great alternative if you have limited space, even though they tend to expand in range. 

If you have more space, you can grow tall-growing tomatoes. If so, the plants need large pots to grow in. They also need to be tied up. With tall-growing tomato plants, you can harvest a larger amount of tomatoes, and there are also more varieties of plants to choose from.

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Both tall-growing and smaller tomatoes can be cultivated in a pot. The smaller ones survive a smaller pot. Picture: Anna Lindeqvist.

2. Pre-cultivate the tomato plants indoors 

Once you have your tomato seeds, you will need to pre-cultivate them. This is important in order for the plant to germinate. The chances of germination are very low if you skip this stage. 

Pre-cultivate the tomatoes indoors during March or April in a mini greenhouse with soil. Rootmaster or Plant start plug box are two good alternatives for mini-greenhouses that fit most window sills. You can also use small plastic trays from the vegetable counter. If you want to, you can sow in small pots from the start, but know that it can be difficult to keep the soil most if doing so. To keep the soil moist, you can cover the pot with plastic foil or a plastic bag - but do not forget to make small ventilation holes. 

Keep the plants in a warm spot until it starts to grow. If you have underfloor heating or a window sill above a radiator, those are good spots to place the sowing at. There are also heating pads made for cultivation. Before the plants visibly come out of the soil, they do not need any light - just heat, water, and oxygen. Lift the lid on the mini greenhouse once a day to ventilate.

There should only be one plant in each pot. If more than one tomato plant arises in one pot, you cut off the weakest one - you can replant that one into another pot. Keep the lid on the mini greenhouse for as long as the plants fit underneath it. 

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Tomato seeds are small, and most seeds usually germinate. Consider how many plants you have the space for and how many plants you would like to grow, and then sow a couple of extra ones. They will make a fine gift! Picture: Lovisa Back.

3. Provide the tomato plant with light

The plant does not need as much heat once the seed has germinated. However, it is very important to provide it with lots of light in order for the plant to thrive and not grow too thin and weak. The light from a window is usually enough around April. If you find it hard to provide the plant with light, grow lights can solve that problem.

4. Replant the tomatoes 

Keep the tomato plants in the mini greenhouse until you see another pair of leaves above the first two heart-shaped leaves. It is now time to replant the tomatoes into a pot with more nutritious planting soil. 

Carefully place the tomato plants, with their roots, into a bigger pot with soil. Preferably place the plant deep down in the new pot’s soil; the leaves should hover right above the soil. The plant is able to grow better when planted in that way since it grows roots alongside its stem. 

If the spring weather is nice you can do the replanting outdoors. Although, you should place the plants indoors again afterward, in the brightest window you have. If it is cold outside, the replanting should be done indoors. 

Keep the soil moist and add nutrition, for example, tomato plant food, or other liquid nutrition a couple of weeks into the new pot. Keep fertilizing regularly. When the tomato plant has grown bigger, replant again. Add properly with soil in the new pot, and again, do so until the soil is right below the plant’s lowest pair of leaves.

If you used degradable paper pots for the first replanting, you can place the paper pot into the soil of the new pot you are replanting in. Keep providing the tomato plant with water often and mix the water with liquid nutrition every once in a while.

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Replant the tomatoes gradually. Allow the roots to fill the entire pot before replanting it into a bigger one. Picture: Lovisa Back

5. Gradually accustom your tomato plant to outdoor life

When the night temperature outdoors stays around +8°C or higher, you can place the tomato plants in a greenhouse or at a sheltered, sunny spot by the wall of your house. Accustom the plants to outdoor life by allowing them just a few hours outside for two to four days. Avoid strong sunlight the first days. If you plan on keeping the plants in pots, they will soon need to be replanted into bigger ones. Smaller shrubbed or potted tomatoes need pots of about 5-10 liters of soil, while tall-growing plants need at least 20 liters of soil. Only place one tomato plant in each pot. Water with nutrition during the whole growing season for stronger plants. 

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Sometimes even small tomato plants need support in the beginning. Picture: Lovisa Back. 

6. Prune your way to a strong tomato plant 

Some varieties of tomato plants need pruning to give as big of a harvest as possible. Pruning is the act of snipping small sprouts that tends to grow at the branch fold of the tomato plant. Shrubbed and most potted tomatoes do not need to be pruned, but with tall-growing plants, it is important to remove the smaller sprouts in order for the plant to grow tomatoes.

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Tall-growing tomatoes usually need to be both pruned and tied up. The black tomato variety 'Indigo Rose', and the striped 'Tiger' F1 are both tall-growing varieties. Picture: Lovisa Back och Anna Lindeqvist.