Using to much light?Seeds dying

10 years ago

A farm across the street just converted to fruit trees and he has a little green house and offered a light 400w hps he said turn light on and feel how far the heat comes down and lower your 3 more inches and set my domed seedlings at first the stretched real fast , so I think there stretching so I lower it I placed it higher than he said, some burned up so I replanted and raised the light I have corn already touching the lid so I have them out for an hr and see if they handle it then put them into another dome bottom no top and as they others get to tall move them over as well until ready to plant outside...? I wish I had just went with heat pads and low flos but he said this light was great for starting and begging your plants please help before I have to start over

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Comments (5)

digdirt2
10 years ago
Your problem isn't the light but the domes. Domes are NEVER left on after germination occurs. The combination of the trapped moisture and lack of air circulation is death to seedlings. Add the heat from the light and it is a wonder any survived.

HPS lights are great to use for seedlings but they do generate a great deal of heat so they are normally kept much further above the plants.

The formula for HPS light is watts= sq.' footprint. A 400 watt bulb gives you approx. a 4' sq. footprint of effective light - 4' wide, 4' long, and 4' high. Since this is a used fixture/bulb I assume then depending on age the footprint may have shrunk to 3' square. But it is seldom less than that unless the ambient temp in the area is quite cool. If that is the case you can lower the light more. I can't give you an exact height without knowing the age of the bulb and the ambient temps but I would never put one closer than 18" from the top of the plants.

Get the dome off, add a small fan to the area to keep the air circulating and adjust the light accordingly.

Dave
CentralCADad
Original Author
10 years ago
Thanks I think that I'll help a lot still use heating pads? And I just put all new seeds in yesterday so take the domes off still? Or wait for seedlings to pop up? Sorry so many questions but the window sill and direct sow or low flos I've used this is to much he said the bulbs about a yr but when I got it I assumed it was broke so I bought e at Home Depot but when I went to set it up to went on there in a niche in the garage so 66& up easy day add the light ok at night it drops to 60's.
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digdirt2
10 years ago
Wait for the majority of the seedlings to pop up and then remove the dome. The rest of the seeds will follow shortly. Also remove them from the heat once most germinate. Heat, like domes is only used for germination.

60-65 is the ideal growing temps once the seeds are germinated.

If new bulb then no closer than 2.5 feet and on for 12-16 hours, off the rest of the time.

Dave
CentralCADad
Original Author
10 years ago
Thanks I'm gonna run with that thanks again
CentralCADad
Original Author
10 years ago
Sorry I'm posting a pic I'm getting spindle little sprouts that appear to be strectching and most rant coming up. I thought to much mositure with heat I added the fan as directed but nothing is coming out right I miss my flos I have numerous varieties in the same dome. As they pop I'm moving them over to an uncovered dome lower right of pic any more advice?