Greenhouse lighting: which lamps to choose?
The short answer: for most greenhouses, LED grow lamps are the best long-term choice — they last 50,000–100,000 hours, produce almost no heat and balance blue and red light. Fluorescents remain the budget pick for seedlings, HID suits large growing areas, and incandescents are only worth it as cheap spot lighting. Here is how the four common types compare.
Which greenhouse lamp type is best?
| Lamp type | Lifespan | Heat | Best for |
|---|---|---|---|
| Incandescent | <1,000 h | High | Spot-lighting single plants |
| Fluorescent | up to 20,000 h | Low | Seedlings, small setups |
| HID | Medium | High | Large growing areas |
| LED | 50,000–100,000 h | Almost none | Best overall value |
1. Incandescent lamps
Incandescent bulbs as supplemental light sources.
Often used as spotlights for a single plant or a small group. Hang them at least 60 cm from plants — they run hot — and place them where they won't interfere with greenhouse work.
Pros: the cheapest to buy. Cons: lifespan under 1,000 hours and most of the energy becomes heat, not light.
2. Fluorescent grow lamps
Fluorescent grow lamps.
Ideal for seedlings: they traditionally emit blue-spectrum light, which promotes growth, and run cool enough to sit just 5–10 cm above plants (raise them as plants grow). T-8 and T-12 refer to tube diameters; newer red-spectrum and full-spectrum tubes support flowering, and T-5 tubes produce three times more light than T-8/T-12 at the same energy use.
Pros: efficient, up to 20,000 hours, seedling-friendly. Cons: lower intensity — not enough as sole lighting for large fruiting crops.
3. High-intensity discharge (HID) lamps
HID lamp in a greenhouse.
Built for large growing areas: high output from a ballast lets them hang high above plants, usually with reflectors. Two types exist — metal halide (blue spectrum, close to daylight, good primary lighting) and high-pressure sodium (red spectrum, supports straight, healthy growth and lasts longer). Replace on the manufacturer's schedule: old lamps still light up but give less light for more energy.
Pros: covers big areas with intense light. Cons: emits heat that can burn leaves if hung too low; hanging height depends on wattage.
4. LED grow lamps
LED lamps for greenhouse plant lighting.
LEDs balance blue and red light, are compact and lightweight, deliver high intensity and produce almost no heat — making them highly energy-efficient.
Pros: 50,000–100,000-hour average lifespan and the lowest running costs — the most cost-effective option overall. Cons: the highest upfront price, especially versus T-5 fluorescents.
How can you cut greenhouse energy consumption?
Lighting, ventilation and heating add up, especially in colder regions. The highest-impact measures:
Seal it: eliminate cracks and gaps, seal door frames, repair holes in foundations, coverings and vents, keep doors closed.
Insulate: on new foundations add 2–5 cm of polyurethane or polystyrene at 45–60 cm depth; on existing ones, seal cracks and gaps.
Windbreak the north wall: evergreens or a temporary fence deflect wind over the structure.
Hold night heat: thermal blankets or night curtains prevent overnight losses; IR and anti-condensation films cut radiation losses under polyethylene.
Automate: service heating annually, circulate air with HAF fans, group plants by temperature needs, and use automated control systems — the same principle as sensor-based watering — to run everything only when actually needed. More on airflow in our ventilation and temperature guide.
Frequently Asked Questions
Which lamps are best for seedlings?
Fluorescent grow lamps — blue-spectrum light promotes growth and they run cool enough to sit 5–10 cm above the plants.
Are LED grow lamps worth the higher price?
Usually yes: at 50,000–100,000 hours they outlast fluorescents roughly 3–5× and waste almost no energy as heat.
Does extra lighting change watering needs?
Yes — longer light hours mean more photosynthesis and evaporation, so soil dries faster. Moisture-sensor-based watering adapts automatically instead of needing a manual schedule change.