Lighting for Hydroponic Tomatoes

Tomatoes need a lot of light, which can present a challenge to hydroponic growers.

When you grow tomatoes in the garden, they receive adequate light from the sun to support their growth, as long as you plant them in a full-sun location. With many hydroponics systems, the issue of light isn't so simple. Hydroponics eliminate many of the disadvantages of growing in garden soil -- pests, diseases and space constraints -- but require careful control of factors like light access that you can usually leave to nature. Tomatoes require high amounts of light to grow, so before planting your first seeds, make sure you've provided adequate light for your plants to thrive.

Things You'll Need

• Light meter
• Artificial lights (metal halide or fluorescent)
• Reflective panels

Instructions

1. Assess the amount of light available in the space where you plan to grow your hydroponic garden. The University of Missouri Extension website recommends using a light meter to measure the amount of light available in footcandles or calculating the wattage available to your plants per square foot. As plants with high light needs, tomatoes require 1,000 footcandles or 20 watts per square foot.

2. Choose an artificial lighting system. As flowering plants, tomato plants require both red and blue wavelengths, which promote the growth of flowers -- which develop into tomatoes -- and leaves, respectively. The Hydroponics Online School recommends high-intensity discharge (HID) lamps if you have no source of natural lighting available to your plants. Metal halide lights -- a type of HID lamp -- provide a good source of both red and blue wavelengths. If you do have a source of natural lighting, you may be able to supplement it with fluorescent tubes, which provide a good source of blue wavelengths for a relatively low cost.

3. Place the lights 6 to 12 inches above the tops of the tomato plants. Plants benefit from being as close to the light source as possible, but be sure to monitor the plants so that the heat from the lamps doesn't burn the leaves. Raise the lamps periodically as the plant begins to grow.

4. Surround your hydroponic garden with panels covered in aluminum foil or another reflective surface in order to maximize the light the plant receives. The Hydroponics Online School also recommends a rotating light so all plants and parts of plants receive adequate light.

Tips & Warnings

• Although effective, artificial lights aren't the most economical choice in most areas, warns the University of Arizona's Controlled Environment Agricultural Center. If you're growing hydroponics for fun, the cost of providing artificial lighting may not be an issue for you, but if you're raising hydroponic tomatoes for a profit, you should consider ways to utilize natural lighting instead to cut costs.

References

• Virginia Cooperative Extension: Home Hydroponics
• Hydroponics Online School: Photosynthesis and Light 7-4
• University of Missouri Extension: Lighting Indoor Houseplants
• University of Arizona Controlled Environment Agricultural Center: Hydroponics
• Hydroponics Online School: Photosynthesis and Light 7-5