White Widow/White Rhino, Help please!

I need to find out about how long I'd have to grow a mother under a 400w MH conversion, in able to get 20 healthy clones off of it.

Any advice would be great. Thank you.

it's not an easy question but if you need that many clones at once you need more mothers - you should stick to 3 or 4 cuttings per mother at one time allowing a few days for recovery - environment is a big factor here - the healthier the plant the more slashing it will take -if it where me i'd keep 4-5 mother plants - and you'll want them at least a foot tall with shoots that are over 5 inches for best results .