There are hundreds of plum varieties grown in CA where nearly all of the store bought plums originate. I couldn't find good pictures by variety but some harvest dates are listed below. Those are a mixture of plums and pluots.

Here is a link that might be useful: plum/pluot harvest dates

beeone-

Depending on where you are buying them from, some grocery stores sell them right out of the box they were shipped in. On that box will tell you the variety. I know Woodman's does this and A place like Sam's CLub or Costco may do this too...

I tried to find the name of a variety of grape I liked at the store, but they had no idea. The box didn't say.

Tilton-

I've always had good luck finding the variety, but maybe some growers don't label? I know a few times i had to pick the boxes up and look on the other side.... This was always on stonefruit (plums/peaches/nectarines/pluots)... A place like WalMart, i've never been able to know.

Thanks for the input. The grocery stores always put them on display so I don't get to see any boxes, and I know the personnel don't know what specific varieties they are, but I will watch for a box and see if I can learn anything. Walmart did have several types of pluots this last year with the variety stated, but they were your standard tasteless sugarless fare.

I would guess the commercial varieties are not hardy here anyway, it just seems odd that they don't seem to be sold by variety and the nurseries also don't advertise commercial varieties. Keeps me from trying to zone-push with plums!

beeone:

Some of the packing houses have their own line of plums. Their plan is to have a constant supply of plums that look similar and ripen all summer long. They think people get confused by specific names. So we aren't their target audience. Most grocery stores have the same plan, generic fruit for the masses.

The store can market Red Delicious apples year around because of storage. Plums have an average market window of 2-3 weeks. So a specific name doesn't mean anything to most people. It's not around long enough for much repeat business.

This post was edited by fruitnut on Tue, Feb 5, 13 at 9:17

Here is a list of ontario grown plums:

http://www.omafra.gov.on.ca/english/crops/facts/07-039.htm