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About Our Propagation Lights
Seedlings need steady light from the day they germinate. A windowsill in February rarely gives enough, so they lean towards the glass and go leggy. A propagation light over the tray fixes that. These are the Sanlight Flex II bars, low-wattage strips that hang close over seed trays and cuttings. They run from 9.5W up to 24W, with prices starting at £43.
The Flex II 10 lights a single seed tray. The longer Flex II 20 and 25 cover a full grow cabinet shelf or propagation bench. Each bar runs at 4000K, a balanced white that suits early growth, salad leaves, herbs and microgreens. When seedlings outgrow the tray and move into fruiting, step up to a full LED grow light. Drivers and splitters live in light controllers and accessories. The full range sits under grow lights.
Why We Chose This Range
"Propagation is where a small light earns its keep. You don't need 200 watts to raise a tray of seedlings; you need gentle, even light held close. The Flex II bars do exactly that, and the IP68 rating means I can hang one right over a misted cuttings tray without worry. Start with the 10 for a single tray. Add the longer bars and a driver as your propagation bench grows."
— Matt, Founder of Greenhouse Stores💡 Tip: Hang the bar around 20cm above the tray and give seedlings 14 to 16 hours of light a day. A plug-in timer keeps it regular. Steady light at this stage builds short, sturdy stems that transplant well.
🔧 Matt's Setup Tip: One driver can run several bars
A single Flex II driver powers more than one bar through a Y-splitter. A 150W driver handles a whole propagation shelf of 10s and 20s. Work out your total wattage first, then size the driver in our accessories section to match.
Propagation lights compared
| Bar | Wattage | Length | From |
|---|---|---|---|
| Sanlight Flex II 10 | 9.5W | 547mm | £43 |
| Sanlight Flex II 20 ⭐ Matt's Pick | 19W | 995mm | £63 |
| Sanlight Flex II 25 | 24W | 1345mm | £82 |
Frequently asked questions
What is a propagation light?
It is a low-wattage LED bar for raising seedlings and cuttings. These Sanlight Flex II bars run 9.5W to 24W and hang close over a seed tray. They give gentle, even light so young plants grow short and sturdy.
Which Flex II bar should I choose?
Match the bar length to your shelf. The 547mm Flex II 10 covers a single seed tray. The 995mm Flex II 20 and 1345mm Flex II 25 light a full propagation bench or grow cabinet shelf.
How close should a propagation light sit?
Hang the bar around 20cm above the tray. These bars are gentle, so they sit close without scorching seedlings. Keep the gap steady and raise the bar a little as the plants put on height.
Can I use these in a damp greenhouse?
Yes, every Flex II bar is IP68 rated. That is full protection against damp and splashes, so you can hang one over a misted cuttings tray or in a humid propagator without any worry.
Do propagation lights need a driver?
Yes, the Flex II bars run from a separate driver, sold in our accessories section. One driver can power several bars through a Y-splitter, so size it to your total wattage across the shelf.
What can I grow under propagation lights?
They suit any young plant: vegetable and flower seedlings, cuttings, salad leaves, herbs and microgreens. For fruiting crops like tomatoes and chillies, move up to a full-power LED grow light once seedlings are established.
Need Help Choosing?
Call our team free on 0800 098 8877