A Grower's Guide to Hydroponic Tomatoes

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Everything you need to know to grow delicious tomatoes indoors
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Hydroponic tomatoes are grown in a nutrient solution with water rather than soil. Growing tomatoes hydroponically allows the grower to raise them in a controlled environment with less chance of disease, faster growth, and greater fruit yield. In this guide, we'll walk you through how to set up a hydronic system and grow your favorite tomato varieties at home!

==Growing Tomatoes Hydroponically==vsfv

  1. Opt for a beginner-friendly hydroponic system, like the ebb-and-flow system.
  2. Add a teaspoon of nutrient solution per gallon of water to feed the plant.
  3. Plant tomato seeds into a hydroponic-specific material, like perlite or coconut coir.
  4. Add grow lights to the hydroponic system so the lights stay on for 16 hours daily.
  5. Allow the fruits to grow and harvest after 8 to 12 weeks!yayaay
Section 1 of 3:

Setting Up a Hydroponics System

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  1. Step 1 Construct an ebb-and-flow hydroponic system for indoor environments.
    Ebb-and-flow systems, or flood and drain systems, flood the tomato plant with nutrient solutions before draining the nutrients when it reaches 2 in (5.1 cm) from the top of its container. This type of system is relatively cheap and easy to build, and we'll explain how to set up and use it in this article.[1] All it requires is a submersible pump, a timer, an air pump with air stone, and a reservoir.[2]
    • Note: Hydroponics and home improvement stores may sell a hydroponics kit with everything you need to set up your system. Alternatively, you can purchase each component separately or find some around your house. Clean any secondhand or previously used components thoroughly before building the hydroponics system.

    Alternative Systems:
    Deep water culture: A simple system for cherry tomatoes and other small plants.[3]
    Multi flow: a larger version of the ebb and flow that relies on gravity. It may be more difficult to build, but it supports more plants.
    Nutrient film technique (NFT): Suspends the plants with roots brushing against the slope of trickling nutrients. It's slightly more demanding and expensive but preferred by some commercial growers.

  2. Step 2 Place your ebb-and-flow system indoors or in a greenhouse.
    Hydroponics systems require precise control to function properly, so they should be set up somewhere closed off from other rooms and the outside. This allows you to maintain an environment of 60–70 °F (16–21 °C) and a humidity of 65% to 75% during the night and 80% to 90% during the day for the best growth.[4]
    • It is possible to grow hydroponics using natural light but keep the system under glass or polyethylene covering, such as a greenhouse roof, and not open to the air.
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  3. Step 3 Fill a large plastic container with water to use as a reservoir.
    Opt for a colored plastic container that doesn't filter light to prevent algae growth. The larger the reservoir, the more stable and successful your hydroponics system will be. Each tomato plant requires about 2.5 gallons of nutrient solution.[5]
    • Many factors can cause the tomato plants to use water faster, so opt for one that can hold "double" the minimum amount of water.[6]
    • You can use a plastic bucket or trash can, but choose a brand-new one to prevent contamination or a lightly-used one thoroughly rinsed with soapy water.
    • Collected rainwater may be better suited for hydroponics than tap water, especially if the tap water is "hard" and has high mineral content.[7]
  4. Step 4 Sit a tray above the reservoir to support your tomato plants.
    This "ebb and flow tray" will be periodically flooded with nutrients and water the tomato roots will absorb. It must be sturdy enough to hold up your plants (or be placed atop additional support) and higher than your reservoir to allow excess water to drain.[8]
    • These are typically built of plastics, not metal, to avoid corrosion that could affect the plants and wear out the tray.
  5. Step 5 Fix a water pump inside the reservoir to circulate the water regularly.
    A water pump sends the water from the reservoir into the flooding tray from one side to the other. Many pumps have a chart listing the water flow at different heights to limit the risk of spillage. Simply immerse the pump beneath the tray and connect the hose to an outlet to pump water.[9]
    • Use a chart listing to find a pump strong enough to send water from the reservoir to the plants' tray. However, the best action may be to pick a powerful, adjustable pump and experiment with the settings once your system is set up.
  6. Step 6 Install a 1⁄2 in (1.3 cm) fill tubing between the reservoir and flood tray.
    Slip a 1⁄2 in (1.3 cm) PVC tube between the reservoir and the tray, and attach one end between the water pump and the tray so it can flood to the height of the plant roots. Position the inlet and outlet pipes at opposite ends of the tray to promote water circulation. Set two airstones at the bottom of the reservoir to introduce oxygen to the water.[10]
    • If using a bin, drill a 5⁄8 in (1.6 cm) hole for the pipe to slip through.[11]
  7. Step 7 Secure an overflow fitting leading back to the reservoir.
    Attach a second length of PVC tube to the tray with an overflow fitting at the bottom of the roots. When the water reaches this level, it will drain back through this tube and into the reservoir. Keep in mind that the overflow tube should be larger in diameter than the inlet tube from the pump to avoid flooding.[12]
  8. Step 8 Attach a heavy-duty 15-amp timer to the water pump.
    A simple adjustable timer intended for light fixtures can power a water pump regularly. Use it to increase or decrease the amount of nutrients delivered depending on the plants' stage of life. Opt for a heavy-duty 15-amp timer with a waterproof cover.[13]
    • Any water pump should have a way to attach a timer if it doesn't come with one already, but the exact instructions vary by model. Ask the manufacturer if you are having trouble with this step.
  9. Step 9 Test the water pump to see where the water goes.
    If a stream of water fails to reach the tray or excess water spills over the edges of the tray, adjust the settings of your water pump or the size of your drain pipe. Once the water is set to the correct strength, check the timer to see if it sets the pump going at the specified times.[14]
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Section 2 of 3:

Growing the Tomatoes

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  1. Step 1 Plant tomato seeds in a hydroponic-specific growing material.
    Plant the tomato seeds in a nursery tray with rock wool, coconut coir, or perlite mixed with vermiculite. These materials are specific for hydronic systems compared to ordinary soil. Before using, soak the material in water with a pH level between 5.5 to 6.5, aided by a pH test kit.[15] Plant the seed under the soil's surface and keep it under plastic domes to trap moisture and encourage the seeds to sprout.
    • When growing tomatoes, choose to raise them from seeds whenever possible. If you bring plants in from the outdoors, you may introduce pests and diseases to your hydroponic system.

    Growing materials:
    Rock Wool: excellent for the tomatoes, but wear a mask and gloves to avoid irritation.
    Coconut coir: excellent choice, especially when mixed with clay "grow rocks." Low-quality products may require rinsing due to salt content.
    Perlite: cheap and moderately effective, but washes away in an ebb and flow system. Best in a mix with 25% vermiculite.

  2. Step 2 Place seedlings under artificial light for 12 hours once they sprout.
    As soon as the plants sprout, remove the covering and place the seedlings under a light source for at least 12 hours daily.[16]
    • Metal halide lamps accurately simulate sunlight, making them popular for hydroponics systems. Fluorescent, sodium and LED grow lights are also available but may cause slower or differently shaped growth. Avoid incandescent lights, which produce more heat and are inefficient and short-lived compared to other options.[17]
    • Avoid letting the light shine on the roots to avoid damaging them. If roots protrude from the starter material before they are ready to transplant, you may need to soak additional starter material and use it to cover them.
  3. Step 3 Transfer the seedlings into the hydroponic system.
    Wait until their roots start to protrude from the bottom of the nursery tray and the first "true leaf" has grown, larger and different in appearance than the first one or two "seed leaves." This usually takes 10–14 days.[18] When you move them into the hydroponics system, you may place them at 10–12 in (25–30 cm) intervals in a layer of the same material, or transfer them to individual plastic "net pots" containing the same material.
    • If using the ebb and flow system described in this article, the plants are placed on the tray. Other systems may call for the plants placed in a trough, along a slope, or wherever the water and nutrients can reach the roots.
  4. Step 4 Set the water pump to run for 30 minutes every 2.5 hours.
    Keep an eye on the plants: you'll need to increase the watering frequency if they begin to wilt, and decrease it if the roots become slimy or soaked. Ideally, the material the plants are in should barely dry out when the next watering cycle comes along.[19]
    • Even once the watering cycle is established, you may need to increase the watering frequency once the plants bloom and fruit since these processes require additional water.
  5. Step 5 Expose growing tomato plants to 16 to 18 hours of light daily.
    For ideal growing conditions, include a grow light to your hydroponic system to expose growing tomatoes to 16 to 18 hours of light each day. Turn off the lights afterward, allowing them to sit in complete darkness for at least 8 hours. This is optional; however, relying only on sunlight may result in slower production.[20]
  6. Step 6 Stake tall tomato plants to encourage growth and stability.
    There are two kinds of tomato plants: determinate and indeterminate. Determinate tomatoes are stockier, less aggressive vines that stop growing at a specific size. Indeterminate tomatoes require stakes to grow upright. A simple way to do this is through a single-stake system. Place the stake within an inch of the plant's base and stem, and use a string to tie the plant to it loosely.[21]
    • Stakes can be made of wood, plastic, or metal. However, metal stakes are the most durable.
    • Even though determinate tomatoes will grow without staking, you risk lower yields if you do not stake the plants upright. When the plants set fruit, they may droop and come into contact with the growing medium.
  7. Step 7 Prune tomato plants regularly to prevent infestation and disease.
    Prune tomatoes by breaking off all of the lower stems that will come in contact with the water first to prevent disease transmission. Use your hands or take sharp, sterilized scissor-type hand clippers to prune. Remove nonbearing branches and drooping limbs by cutting close to the stem at an angle.[22]
    • Examples of indeterminate tomatoes are heirloom varieties like Cherokee Purple, Stripe German, German Johnson, and Black Krim.
    • Edible Gardening Expert Erin Hosteler recommends avoiding pruning determinant tomatoes. "[These] tend to grow and send out their productive energy both up and out [...] With determinate tomatoes, you get fruit that ripens all at the same time, [so…] those are the ones you would not want to prune because when you [do], you're cutting off growth that's [coming in] horizontally [and] reducing your yields."
  8. Step 8 Brush the tomato plant leaves with pollen daily.
    When the tomato plants bloom, since there are no insects in your hydroponics environment to pollinate them, you'll need to do it yourself. Purchase pollen and wait until the petals bend back to expose the round pistil and the pollen-covered stamens or long, thin sticks at the flower center. Touch a soft paintbrush to each of the pollen-covered stamens, then touch the rounded end of the pistil. Repeat daily.[23]
    • It can take 8 to 12 weeks from the start of planting to fruiting the tomatoes.[24]
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Section 3 of 3:

Creating Good Growing Conditions

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  1. Step 1 Use thermostats and fans to regulate the air temperature.
    As a reminder, during "daylight" hours, the air temperature should be 60–70 °F (16–21 °C) and at night 55–65 °F (13–18 °C)[25] Monitor the temperature while the plants grow, as it could change with the climate or tomatoes' life cycle.
    • Pay attention to the growing solution temperature as well. This should be between 68–72 °F (20–22 °C). However, you can keep it within a reasonable range. If it goes slightly outside of it, then that is fine. Avoid letting the growing solution temperature go below 60 degrees Fahrenheit or above 80 degrees Fahrenheit.[26]
    • Running a fan in the room that exhausts to the outside or another room is optional. It can also make pollination easier.
  2. Step 2 Add 1  tsp (4.9 mL) nutrient solution to the reservoir of water.
    Choose a nutrient solution made for hydroponics, not ordinary fertilizer. Generally, 1  tsp (4.9 mL) per 1 gallon (3.8 L) of water is sufficient.[27] But, since your system's needs vary with tomato variety and mineral content of your water, you may need to adjust the amount or type of nutrient solution you use. Follow the instructions on the packaging to determine how much you need to add to the reservoir.
    • Avoid "organic" solutions, which may decompose and complicate caring for your system.[28]
    • Two-part nutrient solutions create less waste and can be adjusted if problems arise simply by mixing them in different amounts, making them preferable to one-part solutions.[29]
    • You may wish to use a growth-focused formula while the tomatoes grow, then switch to a bloom formula once they flower to meet their new nutrient needs.
  3. Step 3 Test the water so it stays between 5.5 and 6.5 pH levels.
    Use a pH test kit or litmus paper to test the pH of your nutrient and water mix once it's had time to become an even mixture. If the pH is not within the range of 5.5–6.5, ask a hydroponics store or gardening store employee about materials to lower or raise the pH. You can adjust the pH of the reservoir with acidic or basic additions.[30]
  4. Step 4 Regularly measure the concentration of nutrients using an EC meter.
    An electrical conductivity meter or "EC meter" may be expensive. Still, it is the best way to measure the nutrient concentration in the water. Results outside the range of 2.0–3.5 indicate that the water should be changed or partially changed.[31] EC meter testing works best when using two-part fertilizers. If you do not have an EC meter, look for the following signs in your tomato plants:[32]
    • Leaf tips curling downward may mean the solution is too concentrated. Dilute with pH 6.0 water.
    • Leaf tips curling upward or a red stem suggest the pH is too low, while yellow leaves indicate the pH is too high or the solution is too dilute. In any of these scenarios, change the solution as described below.
  5. Step 5 Switch the water and nutrient soil every two weeks.
    If the water level in the reservoir drops, add more water, but do not add more nutrients. Every two weeks, or once a week, if your plants do not look healthy, empty the reservoir completely and rinse the support material and roots of the tomato plants with pure, pH 6.0 water to leach away mineral buildup that could cause harm.[33] Fill the reservoir with a new water and nutrient solution, balancing the pH and letting the mixture become even before you start the water pump.
    • You may use the water used for leaching to water regular garden plants.
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Expert Q&A

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  • Question
    Are pesticides necessary for growing hydroponic tomatoes?
    Andrew Carberry, MPH
    Andrew Carberry, MPH
    Food Systems Expert
    Andrew Carberry is a Food Systems Expert and the Senior Program Associate at the Wallace Center at Winrock International in Little Rock, Arkansas. He has worked in food systems since 2008 and has experience working on farm-to-school projects, food safety programs, and working with local and state coalitions in Arkansas. He is a graduate of the College of William and Mary and holds a Masters degree in public health and nutrition from the University of Tennessee.
    Andrew Carberry, MPH
    Andrew Carberry, MPH
    Food Systems Expert
    Expert Answer
    Because they are in a more controlled (indoors) environment, there is less need for pesticides with hydroponic tomatoes.
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  • Question
    How does this work? Why doesn't the plant drown?
    Community Answer
    Community Answer
    The plant doesn't drown because the water is allowed to drain from the plants and medium in the main container into the reservoir below. This allows the plants to receive water and nutrients, but also ample amounts of air. For example, most rockwool mediums are comprised of more than 80 percent air after the nutrient water is allowed to drain. This is because of the many microfibers that make up the rockwool being perfect for retaining water, but allowing it to drain quickly and pull air into the medium as water flows out of the fibers.
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  • Question
    Does the outflow tube need to reach down to the bottom of the tube so that it can fully drain the tub?
    Community Answer
    Community Answer
    Yes. The overflow tube needs to be long enough to go down to the bottom of the tray. That way, when the tray is full, it will automatically make a "siphon" and empty the tray totally, thus avoiding drowning the roots.
    Thanks! We're glad this was helpful.
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References

  1. ↑ http://www.homehydrosystems.com/hydroponic-systems/ebb-flow_systems.html
  2. ↑ https://www.bootstrapfarmer.com/blogs/hydroponics/start-your-own-ebb-and-flow-system
  3. ↑ http://www.simplyhydro.com/home_grow_tomatoes.htm
  4. ↑ https://cales.arizona.edu/hydroponictomatoes/system.htm
  5. ↑ http://www.homehydrosystems.com/system_plans/Other%20Hydroponics%20Related%20Designs/Tips%20for%20Growing%20Plants%20in%20Hydroponic%20Systems/Tips%20for%20Growing%20Plants%20in%20Hydroponic%20Systems.html
  6. ↑ http://www.homehydrosystems.com/articles/reservoir%20size/reservoir%20size.html
  7. ↑ http://www.hydroponics-simplified.com/hydroponic-solution.html
  8. ↑ http://www.homehydrosystems.com/hydroponic-systems/ebb-flow_systems.html
  9. ↑ https://www.electroschematics.com/water-pump/
  1. ↑ https://fifthseasongardening.com/beginning-hydroponics-walking-through-a-simple-diy-hydro-setup
  2. ↑ https://rgjhydroponics.weebly.com/build-your-system-2.html
  3. ↑ http://www.homehydrosystems.com/hydroponic-systems/ebb-flow_systems.html
  4. ↑ http://www.homehydrosystems.com/
  5. ↑ https://rgjhydroponics.weebly.com/build-your-system-2.html
  6. ↑ https://ohioline.osu.edu/factsheet/hyg-1437
  7. ↑ http://www.simplyhydro.com/home_grow_tomatoes.htm
  8. ↑ http://www.tomatodirt.com/tomato-grow-lights.html
  9. ↑ http://www.simplyhydro.com/home_grow_tomatoes.htm
  10. ↑ http://www.homehydrosystems.com/system_plans/Other%20Hydroponics%20Related%20Designs/Tips%20for%20Growing%20Plants%20in%20Hydroponic%20Systems/Tips%20for%20Growing%20Plants%20in%20Hydroponic%20Systems.html
  11. ↑ https://extension.umn.edu/how/small-scale-hydroponics
  12. ↑ https://extension.uga.edu/publications/detail.html?number=C1150&title=staking-and-pruning-tomatoes-in-the-home-garden
  13. ↑ https://extension.uga.edu/publications/detail.html?number=C1150&title=staking-and-pruning-tomatoes-in-the-home-garden
  14. ↑ https://www.bhg.com/how-to-pollinate-tomatoes-7550565
  15. ↑ https://letpot.com/blogs/hydroponic-plant-growing-knowledge-and-tips/how-to-grow-hydroponic-cherry-tomatoes-indoors
  16. ↑ http://www.simplyhydro.com/home_grow_tomatoes.htm
  17. ↑ http://www.homehydrosystems.com/articles/Nutrient%20Solution%20Temperature/Nutrient%20Solution%20Temperature%20is%20Important.html
  18. ↑ https://extension.umn.edu/how/small-scale-hydroponics
  19. ↑ http://www.hydroponics-simplified.com/hydroponic-fertilizer.html
  20. ↑ http://www.simplyhydro.com/home_grow_tomatoes.htm
  21. ↑ https://ohioline.osu.edu/factsheet/hyg-1437
  22. ↑ https://ohioline.osu.edu/factsheet/hyg-1437
  23. ↑ http://www.simplyhydro.com/home_grow_tomatoes.htm
  24. ↑ http://www.simplyhydro.com/home_grow_tomatoes.htm

About This Article

Erin Hostetler
Co-authored by:
Erin Hostetler
Edible Gardening Expert
This article was co-authored by Erin Hostetler and by wikiHow staff writer, Mason Martinez, BA. Erin Hostetler is an Edible Gardening Expert and the Owner & Farmer of The Patio Farmer, a small business based in Charlotte, North Carolina. With over 10 years of experience working on farms and growing food, Erin specializes in providing consultations, installations, and custom maintenance plans for people wanting to grow food in small (or large) spaces at their homes and businesses. Erin loves teaching other people the magic of growing your own food. She's a firm believer that there is a green thumb in everyone! Erin has degrees from Appalachian State University and King's College London, both of which guided her to start her business. This article has been viewed 581,713 times.
4 votes - 100%
Co-authors: 26
Updated: September 2, 2024
Views: 581,713
Categories: Featured Articles | Growing Tomatoes | Hydroponics
Article SummaryX

To grow hydroponic tomatoes, start your tomato seeds in a nursery tray using rock wool or coconut coir soil. Once your seedlings develop leaves, transfer them to your hydroponic system and add artificial lights. To water your plants, run your water pump at least every 2 1/2 hours. For ideal growing conditions, keep the temperature at about 55 to 75 °F. When your plants flower, pollinate them by hand with a paintbrush. For more from our Gardener reviewer on setting up an ebb and flow system, keep reading!

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