hi new..

I am guessing that you have some Flurescents and an HPS..

and you want to know when to switch to the HPS/HID?


Are you starting from seed or clone?

A clone with legs (roots) can take an hps right off the bat.. just keep it far away..
start at 24inches + and slowly move down (evreyday a couple inches)


If you are starting from seed you can use the hps also.. but it is a waste of electricity to use such a big light on a plnat that is just a seed..lol...

and you will have to watch the seedling closley and water it every couple hours because of the heat generated by the HID..


Basically,
.. once you notice that the plant is stable... 3-4 nodes... you can bring in the HPS.. start far away and bring it in..a couple inches a day

make sure you have a fan blowing between the tops of your plants and the light..



and now you know!!!!


happy growing : )