different varieties ripen at different times of the year. some of the early varieties ripen around Thanksgiving, others ripen 1,2,3 months afterwards.

in zone 7, cool weather helps citrus to change colors.

I'd hold until just before frost in your area. Maybe mid-October before picking one. Check it and see. Maybe in two weeks they might start to turn color. You could also cover them up with a blanket when first frost threatens, to give them just a bit more time on the tree.

What do you plan to do with them?

I mainly plan on using them as a substitute for lemon juice. I have heard they are very good for this. I may even make a "lemon" pie with them. I will try at least one when it is preferably dead ripe as a grapefruit. I have read they are good with a sprinkling of sugar.

I harvested 4 dunstan citrumelos from the ground underneath my tree a few days back and these fruits are great for anyone who loves grapefruit juice and wants to grow Citrus in zone 7. I juiced a fruit and diluted with slightly more water than juice and added sugar. It tasted almost identicle to grapefruit juice. These fruits are more sour than typical grapefruit and will likely make a great lemon/lime juice substitute if the juice is used straight. I plan on freezing the juice for later use.

Sounds great! Was there any hint of trifoliate in the juice?

My Dunstan has not bloomed yet.

'Maybe next year', as they say.

Maybe a trace of something that said not 100% grapefruit BUT nothing that was off putting to me at least. These fruits look and smell just like grapefruit and I am very excited about being able to grow a good tasting citrus in zone 7. Because they are seedy and yield slightly less juice than commercial grapefruit (and more sour) they might not be of much interest to someone who can grow the real thing but for someone in zone 7 who loves grapefruit and wants to grow their own, dunstan is a God-send. I also plan on playing around with the juice using it in place of lemon and/or lime. I am told these make a great tasting pie and I believe they would.

That's really good news! Thanks for the good report. Can't wait until mine start to bear. Even if they don't taste good, they will be a very interesting ornamental.

My first Rio Red Grapefruit of the season. I have about 3 dozen nice fruit on a tree planted 2 years ago. Only had a dozen fruits last year. It was a little more sour than usual and the color change of the rind was just starting. I picked another a week later and there was much improvement in the flavor. Very juicy this year. I agree, you just have to start sampling and see what you have.

tree

That is a beautiful tree and fruit! Looks delicious.