Lime and Reusing Soil

I grow in potting soil and add dolomite lime to regulate Ph. When a plant is harvested I put the clumps through some chicken wire and the soil back into the soil bins.


My question is, do I have to, or should I add lime each time I finish a pot?

During the short duration of an indoor weed grow, most of the lime you initially added is still going to be at work. In agriculture, coarse field lime is most effective the 2nd year after application and works into the 3rd and 4th years. Fine ground dolomite is effective quicker, but it still lasts quite a while. If you're concerned you might take the pH of your soil. I'd probably just add about a half dose to the soil. 1 TBL per gallon of soil is commonly recommended, I just throw in a fistful per 5g pot when I am mixing soil.

The lime I am using is a very very fine powder, it's like baby powder.

Well that's what you want, as long as it is dolomite or regular lime. (dolomite has MG, whereas regular limestone has little to none. Both are just ground up rock) Don't use hydrated lime, like you use to stripe ball fields or use in masonry.

Picked it up at the hydro store. I was wondering if the lime would leach out eventually, or if for example it became necessary to flush.

I'm not one of those who flush plants unless I'm pretty sure it's going to die if I don't. I don't flush pre harvest either.

I reuse my soil twice before I dump it, and flush the shit out of it before reuse. I essentially try to bring the soil back to it's original composition, so I personally add some more lime. If you do not flush, I wouldn't add anymore.