There are quite a few things that could have caused your cherry tree to drop its blossoms. Lack of water, insufficient pollination, and frost damage are some of the most common problems (though the latter seems unlikely in Southern California). However, it could also be the case that your cherry tree is not a self-pollinating variety. Most sweet cherry varieties need to cross-pollinate with another cherry tree to produce fruit. If you know your cherry’s cultivar, check online to see if it’s a self-pollinating variety, and if it’s not, you will need to get an additional tree.
Regarding fertilizer, a 10-10-10 mix is best, applied in early spring.
There are quite a few things that could have caused your cherry tree to drop its blossoms. Lack of water, insufficient pollination, and frost damage are some of the most common problems (though the latter seems unlikely in Southern California). However, it could also be the case that your cherry tree is not a self-pollinating variety. Most sweet cherry varieties need to cross-pollinate with another cherry tree to produce fruit. If you know your cherry’s cultivar, check online to see if it’s a self-pollinating variety, and if it’s not, you will need to get an additional tree.
Regarding fertilizer, a 10-10-10 mix is best, applied in early spring.