Marijuana is an annual plant. It is designed to germinate, veg, flower, and die all during one year. Those of us who like to grow from clones sometimes want to keep a favorite mom plant around for years, continually harvesting clones from the top of the plant. Over time, the plant becomes more and more root bound, which is why I root prune my mom plants every so often.
This pictorial will show step-by-step how to root prune and re pot a mom plant.
First, here is a newly rooted clone (AK47) in a party cup. I will transplant her into a 1 gallon pot soon, then she will likely need root pruned in 6 months or so:
Here is my mom plant. She is a Cinderella 99 (C99) that was the source of the eight clones I am currently flowering.
Here she is out of the pot. I like to root prune several days after watering; you don't want to work with a soggy plant.
Here you can see the root system. She is not too root bound, I've pruned much worse. The red balls at the bottom are expanded clay pellets (hydroton) that I use for drainage.
OK, I lay the plant on her side and use a saw or sharp knife to remove about an inch from the bottom.
Here, the cut is complete. The root ball holds together nicely since the plant is root bound. If she wasn't root bound, the root ball would crumble apart.
Now, I cut about an inch off of each side. This shows the end result.
Hydroton goes into the bottom of a new pot.
A layer of worm castings (or other slow release product) is next.
The root pruned plant goes into the pot next.
Fresh soil is place on all four sides, then the pot is top dressed with worm castings.
She will now happily give me cuttings when I need them!