I tried some Cherimoya (Annona Cherimola) fruits last year for the first time and they were delicious. After some reading, I realized although Cherimoya trees are high maintenance, they can be grown in my zone and with some care, they will survive and produce well. I also stumbled on to a FB group, made up of experienced local gardeners growing Annonas and they helped me with a wealth of knowledge that gave me confidence. I do see a few in this forum growing Cherimoyas, so I thought we can share everyone’s experience here.
First, I picked up a couple of trees from Lowes - Honey Heart and Chaffey in June last year. They are propagated by La Verne nursery.
I planted them soon and they immediately started showing signs of sun burn on the leaves. It could have been transplant shock, but they are also known to be sensitive to hot sun, so covered them with 50% shade cloth
They didn’t grow much all year and luckily the winter was mild as I gave up on protecting them again. But the recommendation is to use plastic cover or Christmas lights to add some heat during frosts (for the first year in the ground). After the danger of frost, I manually defoliated the trees and fertilized them with high phosphorus and potassium (3-12-12 GroPower). This is a trick to make them flower abundantly, which I picked up from the local Annona FB group.
The new growth came with a lot of flowers on both trees. The flower look like a miniature banana and interestingly has a strong smell of banana too when it opens.
Getting the flowers pollinated is probably the most labor intensive part. Like avocados, these flowers first open as female (closed) and then turn to male (open) the next day for a few hours before drying up. In their native habitat, these trees co-evolved with a beetle that pollinates these flowers. As you can expect, these critters are not present in Nor. Cal, so I have to take a soft paintbrush, tip the pollen from the male into a cup and stick them into the female flowers. This has to be done 1-2 hours before sunset when success rate is high. To top all of this off, these flowers open over a 1-1.5 month period instead of all at once like stone or pome fruits.
Female flower
The same one, opens up as male the next evening
Pollen collected from the males (the powdery stuff is the pollen, the relatively larger granules are anthers)
After all these steps, I finally see quite a few fruitlets 
Chaffey has grown bigger, produced more flowers and got lot more fruits compared to Honey Heart.
Assuming they don’t drop off, I should be able to see some mature fruits next spring 
I don’t plant to protect them anymore and should survive the conditions here unless we experience unprecedented heat or frosts.
