So, I have a couple Penis Envy jars that Im about to case, but I have a question...

Is it possible to let a jar colonize for months without anything bad happening to it?

Penis Envy drops very little spores, if any at all, and I want to keep a backup of this strain for the future...

So can I let a jar colonize for months as a "mother" cake? (similar to a marijuana mother plant)

Well theirs a couple of easier ways to do this if you want to keep a "mother strain".

You could let the jar colonize for months only if you put it in a low temperature area to decrease the growth of the mycelium otherwise they will just consume your substrate and just die due to starvation.

You could also just a tissue culture from a live cap and place in agar median and wait for it to fully colonize the agar then store in a low temperature area. Or you could make a spore print from a freshly viable cap but from what Ive read PE are a bit difficult to make a spore print from which in turn could be turned into a LC or stored in a syringe(sterile) kept in low tempts to preserve spores.

A lot of this information I found on shroomery website on mushroom cultivation. I also read a marvelous book on mycelium cultivation but it is a little dated but still very good source of knowledge is The Mushroom Cultivator: A Practical Guide to Growing Mushrooms at Home

Good luck to ya I only gave general ideas from there you must dive harder!

What are you planning on doing with that mother cake? Cake-to-cake transfers are not really possible. Grain-to-grain on the other hand is done all the time. In any case, it will keep in the fridge for months.

Your best bet would be to make a clone culture from the stem of a young fruit. Ideally you would grow it on agar to isolate mycelium, but it can also be done easily with a liquid culture. There are tons of methods for sustaining a culture, just be aware that cultures get old and tend to be less vigorous as time passes.

Anything beyond spore syringes is considered advanced, which needs strict sterility using glove boxes or flow hoods. Considering you are messing with cakes, you are probably getting ahead of yourself. Once you get comfortable with grain and bulk methods, then you might want to get into cultures. Everything you need to know can be found on shroomery or mycotopia.

Sorry to be so blunt, but I know I've wasted plenty of time getting ahead of myself. It can be an exciting hobby and you want to be able to do everything but realize that people study and practice for years to develop their techniques for doing this kind of stuff.

You could either make a LC to store in the fridge (Google "Poor Man's Mycelium Syringe Tek" ) or put a dry stem in a sterile bag and use it for cloning when you need to do so.