T5 Fluorescent Grow Lights

T5 grow lights give seedlings, clones and mother plants cool, even light that keeps young growth compact through propagation and veg. Choose single strips for trays and shelves, 4 ft multi-lamp fixtures for veg benches, and 6500K or 3000K Interlux tubes to refresh worn lamps.

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T5 Fluorescent Grow Lights

T5 Fluorescent Lights: HO Strips, Fixtures and Bulbs

T5 grow lights are slim fluorescent tubes, 5/8 inch across, sold as strip fixtures or replacement bulbs. They run cool, so seedlings, clones and mother plants can sit close underneath. SunBlaster, Super Sprouter, LuxStar and Interlux cover runs from 18 inches to 4 ft. Compare models in our test of the best T5 grow lights....

T5 grow lights infographic: strip lights, multi-lamp fixtures and HO bulbs, 6500K vs 3000K, hanging height and lamp life

SunBlaster and Super Sprouter strips have the electronic ballast built in, so there is nothing extra to wire. For long benches, see our 4 ft T5 fixtures. The wider fluorescent grow lights range adds CFLs, and propagation lighting covers full seed-starting setups.

Types of T5 Lights

Single-Lamp Strip Lights

SunBlaster T5HO strips come in 3 ft (39W, 2450 lumens) and 4 ft (54W, 3730 lumens) at 6400K. The NanoTech version adds a reflector that SunBlaster says lifts output by up to 48%. Up to eight strips link on one cord. For a small seed-starting shelf, the Super Sprouter 18-inch fixture is the compact pick.

Multi-Lamp Fixtures

The LuxStar 4 ft fixture runs four 54W 6500K Interlux lamps, about 216W in total. Dual switches let you run two lamps over seedlings and all four as plants fill in. Our fixture test found 4 ft multi-lamp T5s suit mother plants and veg benches rather than flowering.

Replacement T5 HO Bulbs

Interlux 4 ft T5 HO bulbs draw 54W in two colors: 6500K for clones and veg, 3000K for bloom. Both fit standard 4 ft T5 HO fixtures, so you can change spectrum without changing hardware.

How Growers Use T5 Lights

T5s carry seedlings, cuttings and mother plants, where gentle, even light matters more than raw intensity. Run strips end to end along a bench. Our test found the light spreads about twice as far across the tubes as along them, so side gaps stay small.

Frequently Asked Questions

What are T5 grow lights?

They are fluorescent tubes 5/8 inch in diameter, sold as bulbs or complete fixtures. Most growers run T5 HO (high output) lamps, where a 4 ft tube draws 54W instead of 28W for a standard T5. They give off little heat, which suits seedlings, clones and mother plants.

How far should T5 lights be from plants?

SunBlaster recommends hanging its T5HO fixtures 6 to 8 inches above the plant canopy. The tubes give off little heat, so they can sit that close without scorching leaves. Raise the fixture as plants grow, and keep the same spacing across the whole bench for even growth.

T5 vs T8 grow lights: what is the difference?

A T5 tube is 5/8 inch across on a miniature G5 bi-pin base, while a T8 is 1 inch across on a G13 base. The two are not interchangeable, so a T5 bulb needs a T5 fixture and ballast. Match HO lamps to HO fixtures, like the 54W Interlux tubes in the LuxStar.

How long do T5 bulbs last?

SunBlaster rates its T5HO lamps at 10,000 hours, about 18 months on an 18-hour veg schedule. Output fades before a tube fails, so replace lamps on a schedule rather than waiting for them to burn out. Keep spare 54W Interlux tubes on hand for 4 ft fixtures.