April is a dynamic time to talk about fruit trees — as they are all blooming and flushing — and this last week I did so as the monthly speaker for the Ocean Hills Garden Club in Oceanside.
When allotted only an hour to cover “Growing fruit trees in Southern California,” only the vitals can be broached. But I did. I broached them.
Here I broach them again, with you:
Need chill? In Southern California, we can grow almost every type of deciduous fruit tree, but we must be careful about choosing cultivars that are suited to our relatively mild winters, usually of less than 500 chill hours. (For more on chill hours, see this article by the University of California.)
Need heat? If you live within a mile of the beach, some citrus and other fruits that ripen early in the year are unlikely to get as sweet as you hope. To increase the chances of sweet fruit, leave fruit on tree longer or choose varieties that ripen later in spring or summer like the Valencia orange or Gold Nugget mandarin.
Need a pollenizer? Some fruit trees are self-sterile, meaning they need the pollen of another tree in order to produce fruit. Examples are certain plums and pluots.
Size of tree is mostly controlled by you, not rootstock. Trees may be labelled “dwarf” or “semi-dwarf” but still get bigger than you want. No problem. You can control the size of any fruit tree — while still getting a lot of fruit — by pruning.
Full sun, all day, is generally best. Fruit trees planted in maximum sunlight produce more fruit, and have fewer health problems. (See my post, “Where to plant a fruit tree?”)
Don’t plant below grade. Always plant at or a few inches above the level of the surrounding soil. If the tree’s trunk is below grade, then water will collect there and make it vulnerable to crown-rotting diseases.
Bigger containers are better. If you must grow in a container, then go big, like half-wine barrel ultimately. It means you’ll have to water and fertilize less often, and your tree will be healthier because of the bigger soil volume and root system.
Newly planted trees need more frequent watering than older trees. Also, if the tree had been in a container (not bare root), put the water right by the trunk for the first couple months. (See my post, “How to water a newly planted avocado tree.”)
Mulch of wood chips is magical. It will allow you to water less often and less in overall volume throughout the year.
Don’t water wet soil. Most people seem inclined toward watering too often. Make it your goal to always dig to feel the level of moisture around roots before watering. (See this post, “Get your hands dirty to discover the truth about your irrigation practices.” )
Fertilize only as need is shown. I’ve yet to find a tree in a normal backyard that is irrigated attentively and mulched deeply but still needs fertilizer. Maxwell Norton, retired Farm Advisor with the University of California Cooperative Extension, notes similarly in the book, The Home Orchard: “[Fruit trees] grown in backyard settings in typical sandy loam to clay loam soil with proper irrigation rarely need to be fertilized.” (Trees in containers are an exception to this.) (See my post, “Fertile soil can be child’s play.”)
Prune lightly more than once a year if trying to keep the size of deciduous trees down. And keeping trees small from the beginning is far easier than reducing the size of an old tree. (See my post, “My best advice on pruning deciduous fruit trees: Keep them small.”)
Do not thin canopies of citrus and avocado. A healthy citrus or avocado tree should have foliage so dense that you cannot see through to the other side. (See my posts, “How and when to prune citrus trees,” and “Pruning avocado trees.”)
Remove rootstock suckers. They will overtake the scion (the top part of the tree whose fruit you want) and eventually kill it. (See this post: “Beware of rootstock suckers on citrus.”)
Excess fruit can lead to sunburn and even branch breaking. Especially thin fruit that is near the tips of branches. (See my post, “Oh, the mistakes I’ve made: Not thinning enough fruit from a plum tree.”)
Fruit thinning is most needed on peaches and nectarines. It is rarely needed on citrus and avocado.
Remember a tree’s harvest season with a birthday or holiday. Ask my son when we start picking Gold Nugget mandarins and he smiles, “On my birthday!”
Refer to a chart. See this chart by Dave Wilson Nursery for harvest times of deciduous fruit trees, and see this chart by Maddock Ranch Nursery for citrus and avocados. (Also see my post, “When to pick avocados.”)
Kill gophers. They can easily kill young trees, though are not such a big deal for older trees. I’ve used many methods, but my favorite by far is the Cinch Trap. (See my post, “The best gopher trap: It’s a Cinch.” )
Pesticides almost always hurt beneficial insects too. Their use can also put you on a “pesticide treadmill” since a pest’s natural enemies have been harmed and can no longer fight for you as effectively. (See my post, “Don’t spray for citrus leafminers.”)