Growing Tomatoes With Grow Lights

Tomatoes Light Requirements

Lighting for longer than 20 hours a day can harm tomato plants.

Tomato plants will thrive under lights that provide:

20

30

 DLI 

DLI (Daily Light Integral) is how we measure amounts of “plant-useful” light. Once we know a plant’s DLI needs we can match it to the ideal grow light setup.

Day Length for Tomatoes

Lighting for longer than 20 hours a day can harm tomato plants.

Tomato plants do best with a lights on for:

14

18

 hours 

Best Grow Lights for Tomatoes

16 hours of light is a pretty good target for tomatoes — particularly if they’re in your living space and you like to sleep.

You’ll need a fairly powerful light to provide 20-30 DLI in a 16 hour period. The Bright Grow recommendation is the GE 24″ LED Fruit & Flower Fixture. Hang the light just three or four inches above your leaves — raising it to stay just at that distance as the plant grows. This will give an optimal amount of light directly under the footprint of the lamp.
Tomatoes, like all fruiting plants, will grow best under a light that's heavy on the red parts of the spectrum. A "fruit and flower" LED grow light is a good choice for growing Tomatoes. High output fluorescent bulbs can work too but they generally provide less of the important red wavelengths.

Temperature for Tomatoes

Nighttime temperatures above 85°F can delay fruiting.

Germination: 

70

 – 

80

°F 

Growth: 

70

 – 

90

°F 

Many plants germinate at lower temperatures and prefer more warmth for their growth. This is how plants have evolved — sprouting early in the spring when the days are cool and growing and producing as the days get longer and warmer.

Size of Tomato Plants

Tomato roots don’t need very much depth but like a lot of space to spread out.
Typically grows 36

60

” tall

Does well in 12

16

” diameter containers

Tomato Varieties

Look for bush varieties — indeterminate (vining) tomatoes can grow extremely tall.
  • Celebrity
  • New Big Dwarf
  • Little Napoli

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