Mother plants, and keeping them going

i was wondering what techniques you guys use to keep your mothers going. I have 3 mothers, and what i have done is pull the plant out of its container, cut the root ball down, shake out some of the dirt, and replant in the same pot.

is it critical to use a larger pot? i dont want them to get too big.

i use two 70watt MH lamps, with one 150watt HPS. i share the mother closet with the clones that are rooting.

i want my mothers to stay small, and not use too much resources. I take 9 clones from each plant for every crop.

how often should i change dirt? would it be better to use hydro for the mothers? are there any nutes that would inhibit the plants or roots from growing too much?

jqp

you use the bonsai technique. it is in the FAQ. but it is a great way of keeping them small Short but still able to get a lot of clones off of it.

am i using the appropriate method for the roots though? will the bonsai method keep the root ball small?