Q. I have a very nice, fairly young (more than 5, less than 10 years) orange tree. Last year it produced a huge quantity, and the fruits were ultimately quite small, although very tasty. This year there were just as many blossoms, but somewhere in that timeframe we had hot weather and about 90% of the blossoms fell off. Thus the amount of fruit remaining was very small. Throughout the course of this summer, we have had many very hot days and I have watered the tree much more frequently than I would normally. I watered on extremely hot days, but not necessarily every day. Now, in October, the fruits are very large (not as big yet as grapefruit, but large anyway). As the weather is slowly cooling down, how frequently should I water to make sure that these fruits don’t drop off before they are ripe?
The hot weather didn’t directly cause your tree’s flowers to drop, although that is an understandable conclusion. If the tree is not otherwise stressed (such as an extended irrigation failure), blossom drop and failure to set fruit is most likely the result of lack of pollination. During extreme heat, bees tend to be less active so more flowers end up unpollinated. Keep in mind that citrus normally tends to drop an enormous amount of tiny fruit during the best of times. We were reminded of this when we placed a large fountain under our lime tree. We spent more time removing citrus detritus than we did running the thing.
Now that the weather is cooling off you can cut back on irrigation. There’s no magic formula for irrigating as the weather changes, unfortunately. I recommend using a narrow trowel to check the soil moisture several times a week. Just dig down 2 or 3 inches a foot or two from the base of the tree – if the soil is moist you won’t need to water. If it’s muddy, hold off on watering until things dry out a bit. If it’s dry, give the tree a nice drink. Aim to water the ground out to the dripline, which is where the tree’s canopy ends. Citrus roots are dense and tend to stay close to the surface, so watering the whole area under the tree canopy is more important than deep watering in one or two spots.
Q. Now that the weather is getting cooler, should we turn our compost more or less frequently?
This depends on how quickly you want to have finished compost. During the cooler months, compost will not break down as quickly and may even go dormant. If the bin is covered, everything will just sit there. If the bin is uncovered and gets rained on, things can get unpleasant as the wet compost sits undisturbed since there can be pockets of anaerobic bacteria that produce an awful smell.
We like to keep the compost turned and moderately moist (like a squeezed-out sponge). Watching the steam rise off the compost right after it’s been turned is one of life’s little pleasures.
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu
