pexels photo 4199761
pexels photo 4199761

How to Grow Hydroponic Tomatoes

You have decided to grow tomatoes. Great idea! They are delicious and nutritious. Even more intelligent is your choice to cultivate them hydroponically. Here in this article, you will find out how to grow hydroponic tomatoes from seed to fruit

Hydroponic Tomatoes Courtesy of Advanced Nutrients

Why Grow Hydroponic Tomatoes? 

Recently, hydroponic cultivation has been increasing as more people (both commercial and hobby growers) use this method to grow fruits and vegetables. Tomato plants are known to be vulnerable to a lot of pests and diseases. A proper indoor-grown hydroponic tomato has advantages over outdoor, soil-grown tomatoes. 

  • Hydroponic tomatoes that are grown indoors or in greenhouses are free from pests 
  • Indoor hydroponic tomatoes have a longer growing period because appropriate temperatures and other required factors for fruit production can be maintained indoors. 
  • The fruits of hydroponic tomatoes are healthier because nutrients are readily available to the root of hydroponic plants. 

Preparing to Grow Hydroponic Tomatoes 

Are you ready to grow your hydroponic tomatoes? Before you proceed, you should know what you need and how to get the required items. 

You will need: 

  • Tomato seedlings 
  • Hydroponic system 
  • Plant growth medium 
  • Plant trellises or stakes 
  • Water and nutrient solution 

1) Acquire Tomato Seedlings 

Tomato Seedlings Image by Gardening With Children

To grow any crop, you need healthy seeds or seedlings. To get seedlings for hydroponic tomatoes, you should consider sprouting them yourself in a soil-free medium. Seeds grown for hydroponics should not be germinated with soil because they can carry microbes from the soil into the system. 

You can germinate the seed of tomatoes in Rockwool. Make sure that you soak them in pH4.0 water before you cover them. Tomato seeds typically germinate in 5-8 days. When you see the leaves of the young plants, uncover them and place them under a light source. You can give them sun or grow lights.  

After a month (or when you see the true leaves of the plant), your tomato seeds are ready to be transplanted into a hydroponic system. 

2) Choose A Hydroponic System 

There are different types of hydroponic systems, and tomatoes can grow in all of them. Types of hydroponic systems include: 

  • Ebb and flow: Nutrient solution floods and drains in this system 
  • Deep water culture: Plants are fully or partially submerged in nutrient solution 
  • Nutrient film technique: Shallow stream of water passing through the root of plants 

You can purchase a hydroponic system at a local hydroponic store, you can order online, or you can build one yourself. 

The two significant soil functions are to provide nutrients and anchor to your plants. In hydroponic systems, you feed your tomato plants with the nutrient solution while you anchor them with the growth medium. A growth medium prevents your plants from falling over and prevents pests from entering the nutrient solution. 

Recommended growth media are: 

  • Rockwool 
  • Clay pellets 
  • Perlite vermiculite 
  • Coco coir 

You can use any growth medium you prefer 

4) Feed Your Plants a Nutrient Solution 

A nutrient mix or solution is specifically made for hydroponic plants. You should buy a solution that is suitable for tomato plants. Keep in mind that tomatoes require different amounts of nutrients in the various stages of their lifecycle, so you should buy nutrient solutions for the vegetative, flowering, and fruit production stages of your plants. 

Purchase your nutrient mixes at a local hydroponic or gardening shop. Be careful not to buy organic solutions because these solutions decompose and are challenging to maintain in hydroponic systems. 

5) Trellises or Stakes for Your Tomato Plants

There are two types of tomatoes. Determinate or bushy plants reach a specific height and stop growing. Indeterminate or vine plants grow continuously and need to be supported. 

Indeterminate tomatoes are recommended for hydroponics because when they become mature, they continuously produce fruits till they die. If you are opting for indeterminate or vine tomatoes, you should place trellises, stakes, or a cage around your plants so that the vines or branches are supported and contained and still give you space to move around in your greenhouse. 

Have you gathered all the needed items?  

What You Need to Know When Growing Hydroponic Tomatoes 

Have you heard of EC before? What about TDS? Do you know the temperature and pH a tomato plant requires? What about the lighting requirement of tomatoes? Read on to find out more. 

EC and TDS

Electrical Conductivity (EC) and Total Dissolved Solids (TDS) refer to the concentration of nutrients in the nutrient mix. All the elements in the mix make up the TDS while the inorganic salts (that can conduct electricity) in the solution determine the EC. Gardeners often use “EC” because the nutrient mix is inorganic, so it is mostly made of salts (which conduct electricity). 

The EC of your hydroponic tomatoes nutrient mix should be 2.0-5.0. You can measure the EC level of your solution with a digital EC meter. 

Temperature and Lighting 

When it comes to lighting, tomatoes are greedy plants. They need as much light as they can get. Their minimum sunlight requirement is 6 hours. If you are using grow lights, provide 12 to 14 hours of light daily. 

The various temperatures most suitable for tomato plants are: 

  • Daytime: 65°-75°F (18°-24°C) 
  • Nighttime: 55°-65°F (12°-18°C) 
  • Nutrient mix: 68°-72°F (20°-22°) 

Never allow the temperature of your nutrient mix to fall below 60°F (15.5°C) or rise above 80°F (26.6°C). Consider buying a thermometer for checking it. 


PH is the measure of acidity or alkalinity. The pH of your nutrient mix is a critical factor. Tomatoes require a slightly acidic solution (5.5-6.5). If the pH of your solution is too high (i.e., it is alkaline), you can use phosphoric acid to reduce it. You can use potassium hydroxide to increase the pH of your solution if it is too low. Test the pH of your solution with a digital pH meter. 

You now have the basics and are ready to grow your hydroponic tomatoes.  

Growing Hydroponic Tomatoes: A Step-By-Step Guide 

1. Transfer Your Tomato Seedlings into Your Hydroponic System 

Once you have germinated your seeds, and they have developed true leaves, you are ready to transfer them. Use only seedlings germinated in a soil-free medium. If you must use seedlings grown in soil, examine the plants for signs of disease. If the plants are disease-free, rinse the roots with pure water before you introduce them into the hydroponic system. 

2. Maintain Healthy Conditions for Your Tomato Plants 

You have learned the requirements of tomato plants. You must maintain the temperature, lighting, pH, and EC in the system. Healthy tomatoes need a lot of water, so you should top up the water regularly. Be sure to measure the EC frequently. With the EC measurement, you will be able to tell if the system needs more nutrients or water. 

If the EC level drops and the water level is high, add nutrients into the solution. If the water level drops and the EC level is high, add water into the solution. 

Do not drown your plants. Tomatoes (like every other plant) can only survive if their roots have a supply of oxygen. Here are a few of our recommendations: 

  • Always make sure that your water drains completely in ebb and flow systems. 
  • In passive systems, leave breathing space for the roots (i.e., do not fill the container with nutrients) 
  • Insert aerators into your system if you are using deep water culture or nutrient film technique 

The type of nutrient mix you should buy should correspond with the age of your tomato plants. If your plants are young, give them growth-focused nutrition. When they start to flower, switch to a flowering solution. 

3. Hand Pollinating Your Tomatoes to Produce Fruits 

Tomato Flower by Green My Lift India

Outdoor tomatoes are pollinated by insects or wind, so gardeners do not have to worry about pollinating their plants. Indoor hydroponic tomatoes, however, should be pollinated by hand. If you are growing your plants in a passive system like a bucket, you can take the plants outside.  

Hand-pollinate your hydroponic tomatoes by rubbing a small paintbrush inside the flowers of tomatoes. Use the same paintbrush and switch between flowers. Tomatoes do not need to cross-pollinate to produce fruits, so you do not need to rub a paintbrush in flowers from different plants. 

4. Prepare the Growing Conditions for Tomato Fruit Production 

Tomatoes are cultivated for their fruits. Unlike herbs and vegetables, tomatoes need special nutrients and other conditions when they produce fruits. The levels of potassium and phosphorus in your nutrient mix should increase when you see flowers. Go to a local gardening or hydroponic shop to purchase nutrients for fruiting tomatoes. 

Tomatoes will not produce fruits if the temperature is below 60°F (15.5°C) or higher than 80°F (26.6°C). Hydroponic tomatoes come with an advantage because the temperature of the room can be set to trigger fruit production even if it is winter. 

Depending on the variety of tomato, you will have fruits in 45-70 days. Congratulations!!! Enjoy your tomatoes. 

Troubleshooting Issues Growing Hydroponic Tomatoes 

Here are some common issues with growing hydroponic tomatoes and some recommended solutions to help:

Issue #1 The Seeds Will Not Germinate 

If your tomato seeds did not germinate after two weeks, try again with new seeds. Remember to soak them in pH 4.0 water before you cover them with Rockwool.  Note that tomato seeds germinate quickly in 70°-80°F (21°-26°C).  

Issue #2 Algae in Hydroponic System 

If algae is in your hydroponic system, that tells you that light is reaching the nutrient. Cover the solution to keep it in the dark.  

Issue #3 Brown Roots 

If the roots are brown, they have died. Did you transfer plants germinated with soil into your system? Are you using an organic fertilizer? Is the temperature, pH, EC of the system just the right amount for your plants? You might need to begin again. 

Other Issues 

If you have considered the questions above and you think that everything is the way it should be, your tomato plants may be lacking a nutrient or are stressed due to pH or EC. Here are some signs tomatoes show in various unfavorable conditions: 

  • pH is too low: Leaf tips curl upwards 
  • EC is too concentrated: Leaf tips curl downwards 
  • High pH or low-quality nutrients: Yellowing of leaves 
  • Potassium deficiency: Yellowing of leaves, flowers fall early 
  • Nitrogen Deficiency: Stunted growth and yellowing of leaves 
  • Phosphorus Deficiency: Abnormal coloration, stunted growth 

Have you ever grown your tomatoes hydroponically? Please share your experiences in the comments below.  


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