Light distance for seedlings

Discussion in 'Indoor Growing' started by asintx, Apr 23, 2006.


Is a 400w MH 36" from my seedlings okay?

  1. Too High

    3 vote(s)
  2. Just Right

    4 vote(s)
  3. Too Low

    0 vote(s)
  1. asintx

    asintx Registered+

    I have some seedlings just up, and have them under a 400w MH 36" above them. I'm concerned about stretching, a problem I have had with unsuccessful grows in the past. Is 36" too high, too low, or just right? I know I will need to lower the light once they are vegging sufficiently.

    I have read various posts in searches and the distances discussed range from 2 feet to 4 feet, so I am not sure what to do.
  2. latewood

    latewood Banned

    If you see stretching, you can lower light as close as your fans will allow you.

    You need a fan solely to blow between the lamp and the canopy. Add an oscillting fan to move air around. With a fan blowing right between the plants and canopy place your hand right above the seedlings...lower your lamp 6" at a time until your hand gets hot! Move lamp up 2-3 inches and test again. If you can have your hand on the top of your canopy for a minute, withyout feeling HOT heat, then the light is NOT too close and won't burn your plants; However, you must monitor this height daily to keep from burning your tops. hope this helps. lw
  3. asintx

    asintx Registered+

    Thanks, Latewood, for the excellent information!
  4. latewood

    latewood Banned

    I would like to add, A little stretching is not always a bad thing. I have found that If I want to grow plants lower in stature. then by stretching them a little, you allow more light penetration to the lower budsights. This is a matter of opinion, but I have a 400w MH for seedling/clone veg.
    How deep, south, asintx? Tx?
  5. asintx

    asintx Registered+

    Yup, south TX.
  6. latewood

    latewood Banned

    I grew up in San Angelo...
  7. krustythfreakinclown

    krustythfreakinclown Registered+

    You are wasting perfectly good money on electricity to power a light you don't need.

    If you get a couple of CFL's, electric cords and cheap reflectors from Home Depot or Lowes, you'll save a TON on electricity.

    Remember, CFL's can get as close as 2 inches from seedlings and you only need 20-50 watts/sqaure foot. And, they burn cooler, and cost less for more light output.

    Good luck!
  8. latewood

    latewood Banned

    although you can have fun and even grow some nice plants using cfl' will never achieve the same results as a 400w HID.

    don't kid yourself...If you are not limited by grow room size or heat, due to poor circulation...Then you need to use HID's.

    I have used cfl's and they do nicely for veg, but do not match any of my HID's; From 250w-1000w. lw
  9. Garden Knowm

    Garden Knowm Registered+

    GULP.... KNOWM FAINTS......

    : )

    taffy stretches
    a giraffes neck stretches to the highest branch..

Share This Page