In San Diego, some areas give good quantities of Minnie Royal and Royal Lee cherries and others do not. Some gardeners have given up on these cultivars. Others have used Royal Crimson as a bridge, and while that seems to help, I want to share how I get success (so far).
First, here is the problem. Royal Lee in the foreground is not yet awake. It has only a couple flowers. Minnie Royal in the back to the left is at 1/3 bloom. Some say the flowers are only receptive to pollen for 12-24 hours, so if I rely on cross-pollination I am losing crop.
This is because each bee pollinates about 50 flowers on each trip out of the hive. That bee prefers to go to a single tree or bush, and find 50 flowers all at once. It is not going to visit Royal Lee to harvest the pollen of solitary blooming flowers.
In low chill areas we get scattered bloom. Here is a mostly asleep Brooks cherry tree, with one solitary flower. This is common. And we can use it to our advantage.
Look closer at that original Minnie Royal tree that was not overlapping with Royal Lee. In this photo I am pointing at my graft of Royal Lee. It has a couple flowers. Thus the bees visiting Minnie Royal will actually visit a couple flowers of Royal Lee.
Here is another example of inconsistency. On this tree the grafts of MR and RL have reasonable overlap. They are at the same stage and will bloom together. MR on right and RL on left. If this was my only tree I would say that they overlapped well.
But when we look closer…. There is a solitary Royal Lee flower in bloom. This will at least partially help prevent crop failure.
If you really want to get cherries in Southern California/San Diego, you have to contend with the scattered bloom and reluctance of bees to visit trees until they hit peak bloom. Since the window of fertility to pollination is around 24 hours, it means a lot of crop loss unless we have the pollinizer grafted in.
With the pollinizer grafted in, scattered blooms becomes an advantage. Some pollinizer is going to have open flowers at the same time as the peak flowering of your tree of interest.
In San Diego then, the cultivars with the most scattered bloom have the most potential to be good pollen sources. For cherries, Royal Lee has exceptionally scattered bloom, more than other cultivars, often lasting up to 6 weeks. I am still learning more about how this applies to pluots and plums.
Those cherry trees are young for our climate. In another 3-4 years performance will pick up. Also, I recommend having trailing rosemary in a pot (or two!) nearby to keep the bees coming year-round and in greater numbers.
Royal Lee in full bloom, and overlapping with Minnie Royal quite well. I should get a full crop, even without the pollinizer graft… if the rest of nature cooperates…
Zaigers/Dave Wilson deserve a lot of credit for these cultivars… And C Todd Kennedy for donating Cristobalina to them as the source of the low chill trait (confirmed via personal communication with people representing both sides of the exchange actually).
Your best bet is more variety. If you have a finicky tree with a small window, plant a variety with a much longer window that will be in bloom throughout your difficult one.
You can always go the extra mile and hit those with a pollen brush.
You are right Don. There are not a ton of options that early. Growing seedlings of intentional crosses could add diversity of early bloomers (at the expense of a lot of work). I would love a Minnie Royal x Black Tartarian cross if it captured the best of both.
The first flower of Brooks (S1S9) grafted into Royal Lee (S1S3) is about to bloom, right as nearby Minnie Royal (S4S6) bloom is trailing off. I believe that both of these only partially overlap Royal Lee bloom, but together I get a full crop. If I approached this like a scientist, I would have to remove that graft and see if it diminishes my crop in the future… yeah, no way! Anecdote is good enough for me here! I started getting great crops when I started doing this. And Royal Lee is probably my favorite cherry. It was as good as Brooks last year, when left to full maturity.
Here is Minnie Royal with no grafted pollinizer. It bloomed first on the higher branches and set almost nothing. For some reason it bloomed later on the lower branches. Royal Lee was in bloom farther away but this Minnie Royal did not set very well.
Despite blooming slightly earlier, when there were fewer pollinizers, this Minnie Royal tree set much better. Why? I think it was because I had grafted a pollinizer (Royal Lee). The overlap was imperfect but it only takes a few early flowers from the graft to really improve things. All other things were fairly equal.
The photos may be difficult to interpret, but there were around 100 cherries on the first tree, and around 500 on the second. Both on Maxma 14.
