How to grow tomatoes

How to grow tomatoes

Like its' relatives chili peppers, potatoes and tobacco, tomatoes originate from South America. The name ”tomato” comes from the word tomatl which means ”the swelling fruit” in the Aztec language. It is a fast growing plant that thrives in hydroponic systems like Botanium.

The familiar tomato smell can be spread by just brushing the leaves of the plant. It comes from a chemical similar to nicotine and is an effective, natural insect repellent.

Choosing a variety

Tomatoes are classified as either determinate or indeterminate. The difference is that determinate varieties grow up to a certain height and then stop, while indeterminate species keep on growing indefinitely. When growing indoors, it is impractical having a plant that gets 2-3 meter tall. Therefore we don’t recommend growing indeterminate varieties in Botanium. Determinate dwarf tomatoes are a much better choice. (See end of the post for recommendations)
Even when growing determinate dwarf tomatoes it is necessary to prune the plant early in their growth.


What makes tomato different from other common plants (like chili peppers or basil) is that they usually need support when they fruit. The branches simply can’t hold the weight of the tomatoes. Therefore it is a good idea to put some kind of stick (around 30 cm or 12” long) in the growing medium early on, after you have planted the seed. Putting in the stick at a later stage is possible but will damage the roots. As the plant grows (and especially when the branches get fruit) attach it to the support with straps or strings.

How to grow from a seed

Planting the seeds: Put 3 seeds one cm (1/2”) below the surface of the growing medium in your Botanium. The seeds usually germinates in 1 week. If you have a cold window sill, you can speed up the germination by putting the Botanium at a warmer spot until It sprouts and need light.

Nutrients: Tomatoes are heavy feeders. For the first month, use 4-5 pipettes of Botanium nutrients for one full water tank. When flowering, use 6-7 pipettes instead. Some people claim tomatoes get better taste by increasing the amount of nutrients even more. When the tomatoes are turning red, experiment with adding up to 10 pipettes for better taste.

Germination:  Usually 2/3 of the seeds germinate within a week. Keep the tallest seedling and (carefully) pull up the other ones. One plant per Botanium is enough since they grow large, and having other plants would only compete for water and light. Make sure the seedlings get a lot of light!

Pruning: Don't skip this step if you grow an indeterminate tomato plant, or you will get large plants that are difficult to support. Determinate tomatoes usually don't require pruning.

As soon as the plant has reached a height of 10 cm (4"), cut off the top quarter of the plant. We know it is hard to intentionally damage your plant that has grown so much, but it will strengthen the main stem and create a more stable plant that can carry the future tomatoes without breaking. 

Flowering: In a few months you will have flowers all over the plant. Since it is growing indoors you need to pollinate it yourself.

Tomatoes are self pollinating, which means that one plant can pollinate itself. Touch the inside of each flower with a brush to spread the pollen. Alternatively, you can carefully flick the flowers. If the plant doesn’t get enough light, the flowers might drop off.

Harvesting: Most tomato varieties turn either red or yellow when they are ripe.

Light: Tomatoes love to get a lot of sun. Using a grow lamp is a must If you plan to grow tomatoes during winter in the north. With too little light, the plants will get long and spindly and will be a mess to support.


Add some basil and mozzarella and make a caprese. Have them in your sallad. Eat them as snacks. Use it as a base for your chili sauces!
Tomatoes lose a lot of taste if you put them in the fridge, so keep them in room temperature. Let them stay on the plant until you are ready to use them.

Recommended varieties:

Balcony red: A compact dwarf tomato that can get up to 30 cm high (12”) with many small red cherry tomatoes. You can buy it here in our webshop

Other dwarf varieties:
Tiny tim
Micro tom

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  • Rasmus

    It’s not a problem until they reach the pump, but it’s best to just rip the roots off whenever they reach the water tank.

  • Bertrand Riché

    I’ve bought some Botaniums and planted tomatoes in them, they’re a month old now and seems to be perfectly healthy! :)
    I have a question though: I’ve seen that one of them has grown a root through the bottom of the growing area and is now sitting right in the reservoir, so it’s constantly in the water.
    Can that harm the plant in any way? Should I cut that root, or can I leave it do its thing in peace?

    Thank you!

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