Mothers need significantly more light than rooting clones.
I keep my mothers in two groups:
One group lives under a pair of T12 shop lights, each with 2x 4 foot 40w cool white bulbs. I recently unplugged one of the fixtures because they were growing too fast. These mothers are meant to just chill out until I need them. If you intend to take clones once a month, this setup is enough light to keep up to 16 mothers in quart pots happy. Remember that they should be kept SHORT under flouros.
The other group are mothers that are being grown aggressively to give maximum cuttings in minimum time. They are also in fairly small pots, but spread across a 5x5 square of floor about 4' from a MH400 with a hortilux daylight blue bulb. It's amazing how fast they grow.
There are many ways to keep mothers. Just watch your mom, and keep adding light until she gives cloneable shoots as fast as you need them.