Your plants will tell you. Start at half strength, watch for signs of tip-burn.
Gradually work up to full strength, or if you are comfortable 'reading' the plants, keep increasing the concentration until you DO see the tiniest bit of tipburn, and note that amount. Then, give a heavy feeding with plain water. Refer to the amount that burned the plants, subtract ~10%, and that is your full strength nute that YOUR plants in YOUR system like.

I would feed twice a week and alternate with waterings of plain tap water (unless your tap water is evil and nasty) if the plants need more juice in between. Every week or so, try to give one watering that flows OUT the drain holes. This will help prevent soil salting.
stinkyattic Reviewed by stinkyattic on . when to feed full strength nutes hi peeps =) i was reading on stinky's grow guide that when the first set of 5-fingered leaves come in its now ready to feed half strength nutes. now my question is this : when you reach this point, when growing in soil how many times would you want to add fertilizer? once a week ? (i water like a couple times on average a week) and when is it time to switch to full strength? thanks! Rating: 5