International Cannagraphic Magazine Forums - ALL ABOUT BONSAI MOMS/MUMS
Check this out. The problem won't be making them grow it will be keeping them small and under control. Advanced nutrients has a nutrient calculator on their site and I think their mother feed iws like week 2 of the regular veg feed. 13 mothers is alot, if you follow the link above you should be able to get 30 clones from each mother when needed and still have to take cuttings to throw out.