I just bought a 250 watt HPS light. My plants are 2 weeks old. How far away should I put my HPS light from the plants. Also, how long do I have to veg for, before swtiching over to flowering?
At least 12" and 4 weeks. I keep my 400w HPS and 400w MH 1 foot from the tops,my 1000w HPS i keep 18" from the tops.
Wow... 2.5ft from the top the whole way? Maybe if ya have temp issues with a 400w... but when I ran mine I could keep it around 8inches from the canopy top without issue. Rather than give some random guess as to where you should hang your light - I would say it heavily depends on your environment. What ya need to do is get a temp sensor on the top of your grow canopy... then move the light around 10inches from the top...wait 10mins and take a temp reading. If you can get that light to 5inches from the top and the temps are just fine, then that's your desired height. With anything less than a 600w, you wont have to worry about bleaching due to the light being so close.... so push the boundaries.
K. So, 5 inches from the top? If you need to see the area, click the closet grow link in my sig and look for the picture.
yeah itsbest just to take the temp and see. As long as u have good air movment between the light and the tops of the plants there should be no worrie
I always use the hand heat test to determine optimal height. Place your hand (palm down) just over the tops of your plants. Hold it there for 1+ minutes. If the back of your hand gets hot then your light is too close. If your hand doesn't get then you are either too far way or just right. Play with it for a little while and you will figure out the right height for your grow box. Good luck.