Grow light bulbs don’t last forever. Even if they’re still turning on, their light intensity gradually decreases over time — and that can reduce plant growth and yield.
So how often should you replace your grow light bulbs? It depends on the type of bulb you’re using.
Dual Spectrum Grow Bulbs
If you use a dual spectrum bulb from seed to harvest, it’s recommended to replace it every 3 to 4 growing cycles.
Over time, the light output degrades even if the bulb still works. This drop in intensity can reduce flowering performance and overall yield.
Metal Halide (MH) Bulbs
Metal Halide grow bulbs typically last 2,000–3,000 hours.
Light output starts declining before complete failure. Many growers replace MH bulbs closer to the lower end of that range to maintain strong vegetative growth.
High Pressure Sodium (HPS) Bulbs
HPS grow bulbs generally last 4,000–5,000 hours.
Although they may still illuminate after that period, light intensity drops significantly. Reduced PAR output during flowering can directly impact yield size and density.
Signs Your Grow Light Bulb Needs Replacing
- Slower plant growth
- Reduced flower density
- Color shift in the light
- Noticeable drop in brightness
Need Replacement Bulbs in Glasgow?
If you’re unsure whether your grow light needs replacing, visit:
Grow a Pear Hydroponics
78 Stanley Street, Kinning Park, Glasgow
Phone: +44 141 429 5008
The Grow Shop
Unit 8, Block 8 Spiersbridge Terrace, Glasgow G46 8JH
Phone: +44 141 737 0377
Leave a Reply