I'm going to be buying a 3month old sugar glider (female) and I was wondering how old does she have to be for her to mate with my 8 month old male?

Due to his age, he will likely try to mate with her as soon as they are put together.

At that age, she is not ready for this and will either be injured in his zeal or by the ensuing pregnancy. You can wait until she is a year old, but introductions between adults are more difficult and it's not good for either glider to be alone in the meantime. :(

I know you're looking to pair the gliders together for breeding purposes, but it would really be in both glider's best interest to be paired with more similarly-aged gliders if you insist on breeding.

You didn't really ask for any more advice than "What age?", but here's my two cents on what you're proposing:

Gliders are complicated creatures, and while they ARE pets, they are still exotic animals with exotic needs. You're new here, and it's great that you're using your resources wisely and looking up all the information you can. :) Keep at it!

That said, you're not very familiar with gliders yet, and glider breeding and husbandry is NOT an easy task ESPECIALLY if you have your gliders' best interests at heart. I don't think anyone with a heart for animals WANTS to be bad parents, but breeding gliders can seem like a very tempting FINANCIAL venture, so much so that you may start to overlook what's best for your babies. Please take time to enjoy your non-breeding gliders and learn their behaviors, wants, and needs BEFORE you jump into breeding. At the very least, you'll be able to tell what's normal fussing and what's an emergency.

There are many breeders on here that can tell you one heart-wrenching story after another, and most (if not all of them) will tell you that raising joeys is often a financially-draining labor of love at the same time that it is a joy. I hope they chime in here, and I hope you consider what they have to say before making your decision. :)

They will mate soon after being put together, but it is NOT SAFE for a female to mate before one year of age. Do not allow your gliders to mate this young. It is physically dangerous for the female and for the babies if she is pregnant before one year, and for the male, he will not be mature enough to be a good parent before around a year. If you get a female under a year old you MUST MUST MUST neuter your male before letting them be together at all, or keep them 100% separate. If you choose to get an older female, you will be able to allow them to be together in a couple of months. Most people do a 30 day quarantine anyways, so if you want joeys ASAP then get a female older than a year. Young gliders will still mate and she can become pregnant pretty soon, but it's very dangerous. Also, consider the existing population of unwanted gliders before you decide to breed. Good luck.

A 3 month old female will probably not yet be mature enough to conceive joeys. Females begin to mature a bit later than males - usually 5 to 6 months OOP.

The problem is that when she does begin to mature the male WILL mate with her each month when she is in heat.

Allowing a female glider to be with a mature male before she is a year old means that she will become pregnant and will be carrying joeys BEFORE she has completed her own growth to a full adult size. Carrying and nursing joeys can put a big strain on her own growing body and reduce the density of her bones because the nutrients she consumes will be used for milk production for the joeys rather than the growth and strengthening of her own bones.

Very young females often do not make good Moms - joey loss and cannibalism is much more common with very young glider mothers. You may be setting yourself up for heartbreak rather than the joy of having joeys to raise.

If you really want to have a pair of breeding gliders - get a female that is a few months OLDER than your 8 month OOP male so she will be about a year old when she has her first joeys.

I just realized you have TWO intact male gliders that are not yet getting along with each other.

PLEASE do not put a 3 month old female in the same cage with two intact males. She could be severely injured by BOTH males mating with her each month.

You may also find that your two intact males will fight even more if you bring a female glider into your home even if you do not yet introduce them to the female glider. Just the presence of a female glider in your home may cause the fighting between the two intact males to increase.