Growing Tomatoes Without Soil – What You Should Know


Tomatoes are a staple in most people’s diets. But growing them at home when you don’t have a lot of space can be a concern for many. Fortunately, tomato plants grow very well in containers, especially when combined with a soilless growing system.

Tomatoes grow very well in hydroponic and aeroponic systems. The system used should have space for the plants to grow without crowding others. Dutch buckets, aeroponic buckets, or deep water culture are good options. Using the correct nutrients and the right pH will encourage healthy plant growth.

If you choose to grow indoors versus outdoors there are other factors such as lighting and pollination to consider. Also, the variety of tomato plants and whether you grow from seed or use seedlings can affect the quality of your plants.

5 red tomatoes in a row
ID 4963205 © Scott74 | Dreamstime.com

Hydroponic and Aeroponic Systems for Growing Tomatoes

If you choose to grow your tomatoes without soil you will be using a hydroponic or aeroponic system. Hydroponics is growing plants directly in water, there are many different systems that can be used for this. I’ll briefly discuss the ones I think are best for tomatoes. If you want to learn more about hydroponics, check out my detailed article, What is Hydroponics.

The other option is Aeroponics. This is growing plants in air and the roots are lightly misted with water. It is still technically another form of hydroponics since, of course, water must be used. Learn more about aeroponics in my article, What is Aeroponics.

Dutch Bucket Tomatoes

Dutch buckets are a simple hydroponic setup where each plant has its own bucket. Nutrient-rich water is pumped from a reservoir and then dripped into the bucket several times a day. The growing medium, such as perlite, will be saturated with water keeping the roots wet but also allowing air to the roots.

The water can be recirculated back to the main reservoir or drained away. A dutch bucket system is one of the easiest systems to set up yourself. All you need are buckets, a water pump, grow medium, drain pipe, and irrigation hose.

Deep Water Culture Tomatoes

Deepwater culture hydroponics is what most people think of when talking about hydroponics. In this system, the roots of the plant are constantly submerged in nutrient rich water. The roots of the plant still need oxygen so an airstone and air pump must be added to the system to allow proper oxygenation of the water.

Deep water culture systems can use buckets or other containers to house your plants. Usually, the plant itself is contained in a netcup with a growing medium to support it. Learn more about Deep Water Culture (DWC) in our article, Deep Water Culture (DWC) Ultimate Guide.

Aeroponic Bucket Tomatoes

An aeroponic bucket system is similar to a dutch bucket system but instead of dripping water onto the roots and growing medium, water is sprayed at frequent, short intervals directly on the roots. This is a system we have used with a lot of success in our grow tent.

aeroponic bucket system in a grow tent with tomatoes and cucumber seedlings
Homemade Aeroponic Bucket System

Less grow medium is required and any excess nutrient rich water can be drained back into a central reservoir. Again we used separate buckets for each tomato plant to help with spacing.

Our other favorite way to grow with aeroponics is the Tower Garden. Tomatoes do grow exceptionally well in the Tower Garden but we found the tomato plants crowded many of the other plants. Or maybe we weren’t ruthless enough in our pruning. If you want to learn more about the Tower Garden check out our article, What is a Tower Garden and How does It Work?

Tomato Varieties for Soilless Growing

The two main types of tomatoes are determinate and indeterminate. Determinate tomatoes are bush-like and have a final or determined size to them. Indeterminate tomatoes are vine tomatoes and will grow forever if you let them.

Both types of tomatoes can be used in your soilless growing system. It will depend on your preferences. If you want shorter bushier plants that may need less pruning then determinate are the right variety.

If you want a plant that will grow upwards and you can train along a trellis, then you want indeterminate tomato plants. Indeterminate plants tend to need more pruning to keep them from growing out of control.

Hydroponic Tomatoes from Seeds or Seedlings

After deciding on what type of tomatoes you want to grow, next you need to decide if you wish to grow your tomatoes from seeds or use seedlings. I have done both and both methods have great results.

If you decide to grow your plants from seeds you will have more selection as you can find seeds from online or in your local stores. My favorite place to buy seeds online is True Leaf Market, they sell quality heirloom and organic seeds. They also ship to the US, Canada and many other countries

Generally, you should be able to get seeds for almost any tomato variety out there. But your time from seed to fruit will take longer than if you used a seedling. One benefit of starting your plants from seed is they can be sprouted directly in the grow medium. Your plants won’t have to undergo any shock from transplanting.

Seedlings can be purchased from your local greenhouse or you can get a cutting from a fellow gardener. I have used both methods with success. Another option is to order from an online greenhouse such as Nature Hills. They can provide you with other options especially if you don’t have a quality garden center nearby.

When getting a cutting you will be taking the pruning or “sucker” that the gardener would usually have discarded. Just place the cutting in some water until roots form and then plant in your hydroponic system. You could likely just put the cutting directly in the system if the bottom of the cutting stays wet.

If you buy your seedlings from a greenhouse, most likely they will be planted in soil. I bought one of the 4 packs of little tomato plants for my system. It is a simple but slightly tedious process to remove the soil from the roots of the plant.

You will gently remove most of the soil from the plant’s roots by hand then place it in a bowl of water. Gently clean the roots of most of the soil. It can be tough to get all the soil off the roots but do your best. A little dirt likely won’t hurt your system but it’s best to have the roots night and clean. Once the roots are free of dirt you can place the plant in your selected growing system with the proper medium.

Remove Soil from Tomato Seedlings
Remove Soil from Tomato Seedlings

Caring for Hydroponic Tomatoes

Much of the care and maintenance that is required for growing tomato plants in soil is the same for hydroponics. You will still need to prune, monitor for pests and disease, and of course, pick delicious ripe tomatoes. But there are a few extra things to monitor in a hydroponic setup like pH and nutrients.

pH Requirements for Hydroponic Tomatoes

Tomatoes grow best with a pH of 5.5-6.5. Checking the pH of your nutrient solution can be performed using a simple dipstick test where you compare the color of the stick to a provided legend. You can also purchase a pH meter, like this one on Amazon, which will give you more accurate results.

It’s good to check the pH of the nutrient reservoir and also the pH of the root zone. You can directly test the water in the bucket of your plants or the water being drained back into the system. By checking the pH of the nutrient solution at the root of your plants you will know exactly the pH level your tomato plant is experiencing.

pH test kit by Tower Garden

Nutrient Requirements for Hydroponic Tomatoes

In hydroponics nutrients need to be added to the water to give the plant all the minerals it needs to grow. Normally these nutrients are added to the soil using fertilizer and many are naturally occuring.

There are many different types of nutrients that plants require to grow well. SOme are classified as macro-nutrients and some are classified as micro-nutrients. Learn more about the nutrients that hydroponic vegetables need in my article, Guide to the Nutrients Your Hydroponic Vegetables Need.

Generally, young plants need a lower concentration of nutrients than adult plants. If the nutrient solution is too strong it can damage your plants.

Tomatoes in the early fruiting stage need higher levels of potassium, nitrogen, and calcium than plants in a vegetative growth stage. This article from Ohio State details specific nutirent concentrations for different stages of the plant.

You can use premixed nutrient solutions or you can mix your own. We had very good success using the Tower Garden’s 2 part nutrient solution. You can also use a 3 part nutrient solution and specialize the mixture based on the stage of growth your plant is in. I like General Hydroponics Flora Grow, Bloom, Micro Combo which can be found on Amazon.

General Hydroponics Flora Grow, Bloom, Micro Combo Fertilizer, 1 gallon...
  • Gh flora series is the original building block nutrient system imitated but never duplicated....
  • Users can adjust mixtures to suit specific plant needs. Enhances flavor, nutrition, aroma and...
  • Contains highly purified concentrates for maximum solubility

Growing Hydroponic Tomatoes Indoors

Hydroponic tomatoes can grow very well both indoors and outdoors. If you choose to grow your tomatoes indoors there are a few more things that you need to consider to make your plants a success.

Lighting Requirements for Indoor Hydroponic Tomatoes

Tomato plants that grow indoors need to have artificial light. Generally, if you keep your lights on for 16 hours and off for 8 hours this will provide the right amount of light for your plants to grow well. You can adjust this timing but it’s a good starting point.

The lights you pick should be a full spectrum LED. Full-spectrum means that different types of light are provided to promote flowering and fruit growth. LEDs are the best option since they use the least amount of energy. Check out my article for more information, Hydroponic Lighting Requirements.

These are the ones we used in our grow tent for tomatoes, Barrina Plant Grow Light, found on Amazon.

Sale
Barrina Plant Grow Light, 252W(6 x 42W, 1400W Equivalent), Full Spectrum,...
  • Full Spectrum - Barrina LED grow lights 4ft provide indoor plants with full-spectrum sunlight...
  • Super Bright and High PPFD - Consuming only 252W with 1152 LEDS totally, replace 1400w general...
  • Easy Installation - With included tape, clips and cable ties, you could install the lights by...

Pollinating Indoor Hydroponic Tomatoes

In the outdoors the bees, insects, and wind all provide methods of pollination. In an indoor setting, you will need to pollinate your tomato plants yourself. Fortunately, tomato plants are known as “self-pollinating”

Self-pollinating plants, like tomatoes, have flowers that contain both female and male parts. The pollen will be transferred from the male part of the flower to the female part flower and fruit will eventually be produced.

With indoor growing, you will need to help the pollen be transferred from one part of the flower to the other. This is done through air movement or gently shaking the plant to get the pollen moving. Some growers will use an electric toothbrush to gently vibrate the plant. Others prefer to have a small fan blowing on their plants. A fan, like this one from Amazon, is useful for pollination and keeping constant airflow on the plant as there would be in mother nature.

Final Thoughts

Tomatoes are an excellent plant to grow without using soil. Hydroponic systems like deep water culture, dutch buckets, and aeroponic buckets are a few ways you can easily grow tomatoes. These systems are pretty simple to set up and tomatoes are a hardy and forgiving plant to grow.

Diane Davies

Diane started out with a not so green thumb. After experimenting with different plants and methods of gardening, she was introduced to the Tower Garden and aeroponics. Now she loves to grow her own food easily on her balcony.

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