Here are the results of my cherry experiments in low chill inland San Diego. Some of these are just grafts and I am extrapolating. My conclusions are much less certain than for peaches and apricots since cherries do not generate full crops for several years, and pollination in So Cal is unreliable given the erratic bloom.
English Morello
Bloom: Mid-April to mid-May
Harvest: pending
Quantity: abundant
Comment: This specimen on Gisela 5 from Raintree was planted last year. It is in my “zone 10b” area on a warm hill that gets first light/warmth in the morning. It is next to a banana plant for crying out loud. Yes, you can get tart cherries in low chill San Diego…abundantly. I can’t wait to try out organza bags and leaving them on the tree to see what flavor we can achieve with extra time, especially in all the warmth and heat. I am hoping for a “cherry pie” type experience of sweet and tart, without added sugar.
Late Duke
Bloom: mid-April through mid-May
Harvest: two cherries (on a very young tree)
Comment: I am amazed the tree set fruit. I take that as a very promising sign. It was a whip last year. It was not expected to set anything for years. Kansas Sweet is known to set well here. Are any Dukes known to fail in Southern California? So far they seem very promising!
Kansas Sweet - too early, young tree, but multiple reports of success.
Montmorency
Bloom: what bloom? A lone flower emerged the third week of May.
Harvest: ha ha ha ha!
Comment: No way this is expected to fruit for me. I am going to graft test varieties on it next year and leave some low test branches to see what happens.
Minnie Royal
Bloom: mid-February to mid-March, peak was first week of March
Harvest: last week of April through second week of May.
Quantity: Moderate on young trees, may turn out to be abundant?
Pollination: seemed to set only where I finger pollinated
Comment: Very sweet, crisp, amazing flavor. Organza bags and leaving the cherries on the tree an extra week or two was the key to high flavor.
Royal Crimson
Bloom: Bloom mid-February to mid-April, peak was first week of March
Harvest: last week of April through last week of May
Quantity: abundant
Comment: Sweet but subacid, not as intensely flavored as RL or MR
Royal Lee
Bloom: mid-February to mid-April, peak was third week of March
Harvest: last week of April through last week of May
Pollination: seemed to set only where I finger pollinated. Late in the season required different pollen source (Lapins and Brooks)
Quantity: Moderate on young trees, may turn out to be abundant?
Cristobalina
Bloom: April (entire month)
Harvest: none (small grafts)
Comment: Cristobalina is the Spanish cultivar that C Todd Kennedy donated to Zaiger in the 80s, which led to the new low chill cherries. A lot of credit goes to Zaiger/DWN on these, they vastly improved it. Cristobalina fruits very well in low chill areas in the Bay Area. In that location it blooms early and fruits earlier than any other cultivar (mid-May this year in the Bay Area). Since it is self-fertile, it fruits even when it blooms by itself. It is a guigne (soft-fleshed). It is very small. I can’t say it is the best tasting cherry in terms of intensity of flavor and sweetness. That being said, it is very pleasing to eat. It is just balanced. I only tasted fruit in the Bay Area. My kids and I loved it. The tree, when loaded with fruit, is absolutely stunning in beauty. The fruit lace the tree, shining like resplendent jewels. Again, this is how it performs elsewhere. I never got any of that in San Diego.
I believe this cultivar was assumed to be low chill because it is early. But it seems chill confused for me in San Diego. Its bloom is late and scattered and its growth is stunted and weak. Perhaps mine just has a virus. However, all the other cultivars on the grafted trees seem fine. I suspect there is no virus, it is just a higher chill cultivar that happens to bloom early, like Apache apricot. That being said, I cut off all my grafts so the book is closed on this one now, for me.
Royal Rainier
Bloom: April (entire month)
Harvest: none
Comment: Royal Rainier was expected to do well here based on positive nursery anecdotes. It seems high chill to me. I am open to exploring it more but I did hack back most of my grafts.
Lapins
Bloom: last week of March through all of April
Harvest: scant, stil ripening
Comment: Lapins is widely reported to fruit in Southern California but I suspect the harvest is scant. My suspicion is that many high chill cultivars of anything healthy will produce “some” fruit. I believe this is true of some cherries too, but there is lack of pollination due to inconsistent bloom. Because Lapins has the S4’ allele, it is self-fertile and bypasses that. I get some fruit every year on small branches, but not enough to satisfy. I believe if pollination was adequate, more cherries would produce scant harvests like Lapins. But that is just my hunch.
Brooks
Bloom: last week of March, throughout April
Harvest: single cherry, ripening now but will wait another week or two
Comment: I put Brooks in “zone 10b” on my hill, zone 10a in my orchard, and zone 9b in morning shade. I got my lone fruit in morning shade (extra chill hours). Human beings are known to extrapolate excessively from limited data, if the narrative is cohesive. So take that with a grain of salt but I am excited about morning shade adding 2 extra chill hours per day! The flavor of Brooks is so good, this is worth pursuing further.
Coral
Bloom: last week of March through mid-April
Harvest: none!
Comment: The allele is S1S3 so you can not use it to pollinate Royal Lee. It pollinates its UC sibling, Brooks.
Governor Wood
Bloom: April
Harvest: none
Comment: This and Coe’s Transparent were the earliest traditional cherries in the Bay Area at my parents’ house, ripening in mid to late May. In San Diego I did not water it enough and it is not a happy tree, crammed in as a test cultivar. Coe’s Transparent tasted better to me in the Bay Area.
Burbank
Bloom: last week of March throughout April (one scattered earlier bloom gave me false hope)
Harvest: none
Comment: I am excited about this cultivar, having read Burbank’s Methods and its pedigree from early cultivars.
Black Tartarian, Black Republican, Van - signs of inadequate chill but they leaf out and catch up and look normal by mid-May. I don’t expect fruit.
Conclusion:
Tart cherries: English Morello is a proven winner in So Cal
Duke cherries: Late Duke and Kansas Sweet are promising
Sweet cherries: Buy Royal Crimson as a pollinator, but Minnie Royal and Royal Lee are the crops you want. You will need something to pollinate late Royal Lee flowers. I use Lapins and Brooks. You must protect the crops for a fully ripe harvest if you want full flavor
Pollination: on young trees I have needed finger pollination to get fruit, but I have young trees.
Location: morning shade seems to “add chill hours”