I am in a similar climate to you, but south of the bay area. I have both Mariposa and WSR. The bloom times do not overlap. I am looking for a pollinator for the Mariposa as well, and plan to graft Satsuma onto it next year. I may try some other pollinators as well. Bay Laurel Nursery lists Catalina, Nubiana and regular Santa Rosa as pollinators for Mariposa.
Here Mariposa blooms first. Just Santa Rosa, not sweeping SR, blooms next. But I have all 3 varieties in one tree so I get plenty pollination. Shiro, Satsuma, and Santa Rosa.
It might make sense to graft some Santa Rosa into the Mariposa for pollination. We get lots of Santa Rosa plums every year, as we are CSA hosts for a farm that grows them, so we are hoping to add more variety with our trees (like Mariposa). The low chill requirements for us are limiting. Some years we’ve only gotten 150 chill hours, so I’m trying to prioritize the extremely low-chill varieties (like Mariposa and Inca).
We are also thinking about the Burbank plumcot, which apparently blooms between the Inca and WSR. Not sure if it would bloom at the right time to pollinate the Mariposa, but maybe.
Update; we had to get rid of the weeping Santa Rosa. It was just planted in the wrong spot. Besides, it’s five years old now, and still no fruit. So it’s gone.
We are planning to put in the Burbank Plumcot and the Mariposa plum, close to our thriving Inca plum. All are supposedly “early” bloomers. It’s possible the Mariposa won’t be pollinated by the other two, but we’re hoping there will be some overlap.
For what it’s worth: the Inca is just about to pop, I can see white buds getting ready. The WSR was usually a couple to three weeks behind the Inca for us.
We are thrilled with the Inca. Excellent fruit quality on a vigorous and productive tree.
Will keep this updated, and in the meantime would love any additional insight that folks have here!
Well, now they seem to be blooming at the same time, so at this point I am clueless why I am not getting any fruit on the Mariposa plum. Flavor King pluot planted right next to it at the same time is bearing well. However, I just grafted Shiro, Inca, Satsuma, Beauty Japanese plums and Flavor Supreme pluot on it or near it. If that doesn’t fix it, nothing will.
You can check out my data entry form at this thread Mar 2:
Feel free to add your blossom schedule once you have all the dates ready to enter; write them down but wait until petal fall to enter all dates. I just Grafted Mariposa near some of my other Asian varieties.
Dennis
Kent wa