If you learn how to grow hydroponic tomatoes, you can have juicy and delicious tomatoes all year round. You will also save a chunk of money in the off-season when tomato prices usually go sky high.
Fresh summer tomatoes are the tastiest, but quite hard to come by in the colder months so hydroponics comes as an economical alternative to stock your fridge with fresh and healthy tomatoes throughout the year.
Introduction to growing hydroponic tomatoes
You do need to have some experience and success in growing leafy greens and herbs in hydroponics before you tackle tomatoes as they are needy as it comes to growing them in a hydroponic system.
Tomatoes need more inputs and care than leafy greens and herbs. They also need more careful monitoring of nutrient mixes, adequate lighting, and a lot of maintenance and pruning.
In addition, tomatoes are vulnerable to a host of different bacteria, virus, fungi, and pests. Tobacco mosaic virus, fungal blight, and various bacterial infections can kill your crop in no time. Whiteflies, many worms, and spider mites can all appear on your indoor grow area, eating and killing your tomatoes.
Fortunately, because they are in a more controlled environment, there is less need for pesticides with hydroponic tomatoes, which is a huge plus.
To reap the benefits of successful hydroponic tomato gardening, you do need to learn the basics of hydroponics using simpler crops like lettuce, kale, basil or thyme which are all less demanding and more resilient.
Should I use seeds or saplings?
Seeds are much safer to start with so we recommend raising your tomato plants from seed whenever possible. If you bring seedlings in from the outdoors, you may introduce pests and diseases to your hydroponics system. A single infected seedling is enough to destroy your entire crop.
If you start with seeds, you will also be able to grow less common and even rare varieties of tomatoes which are not widely available as saplings in nurseries or garden stores.
Determinate or indeterminate varieties
Tomato vines can be either determinate (bush) or indeterminate (vining).
Of these, the determinate (bush) varieties spread and sprawl along the ground, while vine varieties prefer a more vertical growth.
The determinate plants are better for hydroponic gardening, and small indoor grow areas. This is because they grow only to a set height, anywhere from 2 feet to four feet or more. After flowering and bearing fruit, the growth of the plant is greatly reduced.
Popular tomato varieties for hydroponic planting are Brandywine, Matusalah, Giant Beefsteak, Trust, Delilah, Moskvich, Thessaloniki, Brandywine Pinke, Mortgage Lifter and specialty varieties like Cherry Tomatoes, Cocktail tomatoes, Plum Tomatoes, and Italian varieties.
Factors which influence tomato growth
1. Temperature – Tomatoes do well within a temperature range of 55-85 degrees F. Bear in mind that tomato plants can be severely damaged or killed by prolonged cold or even a brief exposure to frost.
2. Nutrients – Tomatoes need properly-designed nutrients which are easily absorbed and well-balanced. You can get by using a general plant nutrient mix designed for hydroponics. However, if you aim for maximum yields, many brands sell specific mixes aimed at tomatoes.
Two-part nutrient mixes are the best for tomatoes. With these, it is easier to achieve the desired level of nutrients. Tomatoes need high levels of phosphorus, nitrogen, and potassium. As for pH, the plants thrive in a slightly higher than average pH of around 5.8-6.3.
EC levels need to be maintained between 2.0-3.5 milliMhos. This can easily be achieved by ensuring the correct mix of nutrients.
If there are any deficiencies in the nutrient levels, pH or EC, the results can be easily noticed on the plants which display the following symptoms:
Yellow leaves - a sign of high pH or low quantity nutrients
Red stems/curled up leaf tips - low pH
Leaf tips curling down - a higher nutrient level than necessary
Early flower falls - potassium deficiency
3. Light – All tomatoes need strong light for at least 8 to 10 hours per day. Fruit production can be maximized by giving 16 hours of light. Some high yield varieties do best with 18 hours of light. Getting the best T5 grow lights is a must!
When tomatoes are fully mature, they also need around 8 hours of darkness for respiration.
As for the lighting, metal halides are the best option due to the powerful light outputs. Others like CFLs and LEDs are also available but may result in less growth.
4. Pollination –Tomatoes need to be pollinated in order to bear fruit, Unless you are going to engage in artificial pollination, the plants must be accessible to pollinators, which can include insects and wind. Obviously, it is difficult to provide pollinator access to plants grown indoors or in greenhouses.
5. Overall environmental conditions – Tomato plants suffer when there are windy conditions, extreme heat or cold, polluted air or soils, or presence of insects, blight or disease. Tomatoes need adequate water, but you need to avoid overwatering as much as you need to avoid drought.
6. Growing medium - Tomatoes can deliver high yields with the right kind of support from growing medium. The option of growing medium is also connected to the technique that you plan to use for hydroponics:
- Rockwool - Drip, Ebb & Flow (Flood and drain systems)
- Expanded clay pellets - deep water culture, NFT, Drip systems
- Coco coir - passive hydroponics
- Perlite/Vermiculite - NFT, Drip system, also used with other growing media like Coco Coir
How To Grow Hydroponic Tomatoes Using Ebb & Flow System – A Step By Step Guide
We opted for the Ebb & Flow hydroponic system as it’s fairly easy to set up and very low cost as you can use the materials laying around the home or buy them cheaply in most home improvement or convenience stores.
You will need the following components:
- A large reservoir tray/tote bin, preferably with a lid
- A smaller tray to hold the plants above the reservoir
- Container pots or net pots for individual plants
- A submersible water pump
- Two PVC tubes, one ½ inch for water intake, and a larger tube for draining
- Growing medium - rockwool, clay pellets, or a mix of coco coir+perlite
- Hydroponic nutrient mix for tomatoes
- A simple plug-in timer
Part 1 - Setting Up a Hydroponics System
The ebb & flow system, which is known as a flood and drain system, got the name because it floods the plants with nutrient solution and then the solution drains when it is about two inches from the top of the container.
Hydroponics stores and home improvement stores sell hydroponics kits which include everything you need to set up your system. Alternatively, you can purchase each component separately, or use those you can find in the home.
Make sure to clean previously used components thoroughly before building your new hydroponics system.
Find a suitable location indoor or in a greenhouse if you have one. Hydroponic system for growing tomatoes requires a precise control in order to function properly, so they should be set up somewhere closed off from other rooms and from the outside.
This will allow you to set the lighting, temperature, and humidity to accurate levels needed for the best growth.
Fill a large, plastic container with water to use as a reservoir. You need a plastic container that does not let in any light in order to prevent the growth of algae. The larger this reservoir, the more stable and successful your hydroponics system will be.
Each tomato plant requires about 2.5 gallons of nutrient solution. However, many factors can cause the tomato plants to use water faster. This is why we recommend that you use a container that can hold double the minimum amount of water.
Use a brand-new container to prevent any contamination of the system, or at least a lightly-used one thoroughly scrubbed with soapy water and rinsed well.
Collected rainwater is far better suited for hydroponics than tap water, especially if your tap water is with high mineral content (hard water).
Fix additional tray in place above the reservoir. This will support your tomato plants. It will periodically be flooded with nutrients and water ebb & flow tray that the tomato roots will absorb.
The ebb & flow tray must be sturdy enough to hold up your plants. It also needs to be placed higher than your reservoir to allow excess water to drain down into it. The ebb & flow tray should be built of plastics, not metal, to avoid corrosion that could affect the plants and wear out the tray.
The next step is to install a water pump inside the reservoir. You can buy a water pump at a hydroponics store, or buy a fountain pump at home improvement stores. Many pumps will have a chart listing the water flow at different heights.
Use the listing to find a pump strong enough to send water from the reservoir to the tray containing the tomatoes. The best solution is to pick a powerful, adjustable pump and experiment with the settings once you have your system set up.
Now install fill tubing between the reservoir and the tray. Using 1/2 inch PVC tubing, or the type of tubing that came in your hydroponics kit, attach one length of tubing between the water pump and the tray, so the tray can be flooded to the height of the tomato plant roots.
Position the inlet and outlet pipes at opposite ends of the tray to enable water circulation.
Install an overflow fitting which leads back to the reservoir. Now attach the second length of PVC tubing to the tray with an overflow fitting, located at a height at the bottom of the roots. When the water reaches this level, it will drain back through this tube and into the reservoir. You get a very simple but effective system.
Bear in mind that the overflow tube should be larger in diameter than the inlet tube from the pump in order to avoid flooding.
Attach a timer to the water pump. A simple timer designed for light fixtures can be used to power the water pump at regular intervals. It needs to be adjustable so that you can increase or decrease the number of nutrients delivered depending on the plants' stage of life.
We recommend that you use a heavy-duty 15-amp timer with a waterproof cover. Any water pump should have a way to attach a timer and some come with one already. Follow the instructions on how to connect and set the timer.
It’s time to test the system. Turn on the water pump and see where the water goes. If a stream of water does not reach the tray, or if excess water spills over the edges of the tray, you will need to adjust the settings of your water pump OR you may need to adjust the size of your drain pipe. Once you have the water set to the correct strength, check the timer to see if it sets the pump starting at the specified times.
Part 2 - Growing the Tomatoes
The initial step is to grow your tomato seeds in a special material. We’ll remind you to raise your tomato plants from seed whenever possible. If you bring plants in from the outdoors, you may introduce pests and diseases to your hydroponics system.
You need to plant seeds in a nursery tray with a special growing material for hydroponics, and not ordinary garden soil. Before using, soak the material with pH 4.5 water, using a pH test kit from a garden store.
Plant the seed under the surface of the growing material, and keep under plastic domes or other transparent material to trap moisture and encourage the seeds to sprout.
You can use the following 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. It works best in a mix with 25% vermiculite.
When the seedlings sprout, place them under artificial lights. As soon as the plants sprout, remove the covering and place the seedlings under a light source for at least 12 hours a day.
Incandescent light bulbs produce more heat than other options so try not to use those if possible. (See our info about light sources in the introduction).
Make sure that the light does not shine on the roots to avoid damaging them. If roots are protruding from the starter material before they are ready to transplant, you may need to soak additional starter material and use it to cover them.
You can now move 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. It will be larger and different in appearance than the first one or two "seed leaves". The “true leaf” will usually grow in 10–14 days.
When you move them into the hydroponics system, you may place them at 10 to 12-inch intervals in a layer of the same material. Alternatively, transfer them to individual plastic "net pots" which contain the same material.
Set the water pump timer. To begin with, try setting the pump to run for 30 minutes every two and a half hours. Do not go more than 2.5 hours without running the pump.
You need to keep an eye on the plants: if they begin to wilt, you'll need to increase the watering frequency. Conversely, decrease the watering frequency if the roots become slimy or soaked.
Ideally, the growing material should just barely dry out when the next watering cycle begins.
You may need to increase the watering frequency once the plants begin to bloom and bear fruit since these processes require additional water.
Set your artificial lights if needed by your setup. For perfect growing conditions, you need to expose growing tomato plants to 16-18 hours of light a day. Then turn off the lights and let them sit in total darkness for about 8 hours. The plants will still grow if you are relying on sunlight, but will likely grow more slowly.
Time will come to stake and prune the tall tomato plants. If you are growing "determinate" varieties, they will grow to a specific size and then stop. “Indeterminate” varieties will continue to grow indefinitely and may need to be gently tied to a stake in order to grow upright. Prune them by breaking off stems with your hands rather than cutting them off.
Bear in mind that even though the determinate tomatoes will grow without staking, there is a risk of lower yields if you do not stake the plants upright. When the plants bear fruit, they may droop and come into contact with the growing medium, which you need to avoid.
When the tomato plants bloom, since there are no insects in your hydroponics environment to pollinate them, you will need to do it yourself. You must wait until the petals bend back to expose the round pistil and the pollen-covered stamens, or long, thin sticks at the flower center.
Pollination is easy: all you need to do is touch each of the pollen-covered stamens (the male reproductive part of a flower) with a soft paintbrush and then touch the rounded end of the pistil (the female reproductive part of a flower). Repeat this daily with all plants.
Part 3 - Creating Good Growing Conditions
You need to control the temperature. During "daylight" hours, the air temperature should be 65 to 75 degrees Fahrenheit. At night it should be 55 to 65 °F. Use thermostats and fans to regulate the air temperature.
You need to monitor the temperature while the plants grow, as the temperature could change with the climate or tomatoes' life cycle.
Make sure to monitor the growing solution temperature as well. It should be between 68 to 72 degrees Fahrenheit. You do not need to keep it exactly within this range. If it goes slightly outside of it, then that is fine. Just avoid letting the growing solution temperature go below 60 degrees Fahrenheit or above 80 degrees Fahrenheit.
Run a fan in the room might be necessary in some cases. A fan that exhausts to the outside or another room may help keep the temperature even throughout the room. The air flow the fan creates may also make pollination easier, although to be certain that your fruits will grow, you may wish to pollinate by hand anyway, as described above.
Add a nutrient solution to the reservoir of water. Choose a nutrient solution made for hydroponics, not ordinary fertilizer. It may sound strange and counterintuitive but you should avoid "organic" solutions as they decompose and make caring for your system more complicated.
Since the needs of your system will vary with tomato variety and mineral content of your water, you may need to adjust the amount or type of nutrient solution you will be using. For a start, follow the instructions on the packaging to determine how much you need to add to the reservoir.
Two-part nutrient solutions create less waste and can be adjusted if problems arise simply by mixing them in different amounts. This makes them preferable to one-part solutions.
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.
Use a pH test kit to test your nutrient and water mix once it has become an even mixture. If the pH is not within the range of 5.8–6.3 you can adjust the pH with acidic or basic additions to the reservoir. Phosphoric acid can be used to lower pH, while potassium hydroxide can be used to raise it.
Installing grow lights is recommended. Artificial "grow lights" will allow you to simulate ideal growing conditions year-round, providing your tomatoes with many more hours of "sunlight" than the garden outside may be getting.
This is one of the major benefits of an indoor growing system. However, if you are using a greenhouse or other area that receives high amounts of natural light, you may accept a shorter growing season and save money on electric bills.
Metal halide lamps simulate sunlight most accurately, making them the most popular choice for hydroponics systems. Fluorescent, sodium, and LED grow lights are also available but may cause slower or differently shaped growth. Avoid incandescent lights, which are inefficient and short-lived compared to all other options.
Monitor the water regularly. An electrical conductivity meter or "EC meter" may be expensive, but it is the best way of measuring the concentration of nutrients in the water.
The results outside the range of 2.0–3.5 indicate that the water should be changed completely or partially. EC meter testing works best if you are using a two-part fertilizer. If you do not have an EC meter, look for the following signs in your tomato plants:
Leaf tips curling downward - the solution may be is too concentrated. Dilute with pH 6.0 water.
Leaf tips curling upward or a red stem - the pH is too low
Yellow leaves - the pH is too high or the solution is too dilute.
In any of these scenarios, change the solution as described below.
Change the water and nutrient solution regularly. If the water level in the reservoir drops, add more water but do not add more nutrients.
If your plants do not look healthy, you should 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.
You may need to do this every two weeks, or once a week.
Simply fill the reservoir with a new water and nutrient solution, making sure to balance the pH and let the mixture become even before you start the water pump. You can use the water used for leaching to water regular garden plants.
This is about it, our fellow gardeners. We hope this article will help you set up a great hydroponic system which will yield delicious and fresh tomato fruit all year around!
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