The Coastal Gardener: Proper pruning helps stonefruit harvest

Pruning of stonefruits and other deciduous fruit trees is one of the most misunderstood of all gardening responsibilities.

In almost all cases, fruiting trees are pruned quite differently than ornamental trees. Far too often I see fruit trees pruned wrong, either at the incorrect time of year, two heavily or two lightly, or in a manner that almost guarantees no fruit will be produced.

Stop. Before you prune another branch on your peach, nectarine, plum, apricot, apple, persimmon, pluot, almond or similar tree, take a few minutes to learn how these trees grow and how they actually produce their fruit. A few wrong cuts can nearly eliminate your crop, but an understanding of just a few basic needs of these trees can greatly increase both the quantity and quality of your fruit harvest. Proper pruning will lead to a healthier tree, with solid structure and delicious fruit yields for decades to come.

Keep in mind, we are talking here about stone fruits and deciduous fruit trees, like those mentioned above, not about citrus, avocadoes and other subtropical fruit trees.

After these stonefruit and deciduous fruit trees have been established for a couple of years, most will need pruning twice a year, with a different purpose at each session. Summer pruning is done immediately following the harvest and its purpose is to manage tree size and tree structure.

As illogical as it may sound to a beginning gardener, pruning a deciduous tree in the winter, with an intention of reducing its size or keeping it compact, is fruitless (pun intended). These winter pruned trees, simply burst out the following spring with a vigor that seems boundless, quickly negating all your winter efforts. Long, stringy, weak stems bolt to the sky, growing several feet in just two or three months, frustrating confused gardeners who, just a couple of months earlier, spent winter afternoons chopping away at the trees.

Even worse, a major winter cut-back of a fruit tree just about guarantees a sparse harvest the following summer. Pointlessly hacking at your fruit trees in winter, in a futile effort to keep them from getting too large won’t work; and it’s probably the most common pruning mistake.

Surprisingly, managing a tree’s size is always accomplished with summer pruning. Instead, the purpose of winter pruning, from December and February in Southern California, is to improve the quality and quantity of your harvest. With proper winter pruning, your fruit will be larger, more prolific and with less potential for infectious diseases.

So, with this newfound knowledge you’re ready to perform your winter fruit tree pruning. But how do you do the pruning? Peaches are pruned differently than plums; apricots different than apples, pluots different than nectarines, and so on; so it’s difficult to generalize. Don’t despair; check back here again next week and I’ll attempt to explain some of the 1-2-3s of this winter pruning chore.

In the meantime, let’s continue our lesson. The other time to prune a deciduous fruit free is during the summer, immediately after all the fruit has been harvested. This may be as soon as late May for the earliest producing trees, but as late as September for others.

Summer pruning serves the purpose of restricting the size of the tree and, especially important, it does not interfere with your fruit production.

In case you’re curious, here’s why summer pruning is the proper time to control the size of a these trees: When a fruit tree is pruned in summer, it reduces the trees potential surface area for photosynthesis and food manufacture and the tree produces only a small amount of growth following the pruning. Besides, since deciduous trees put on most of their growth in spring anyway, a summer cut only produces a small amount of re-growth. Finally, summer pruning also reduces the amount of food the tree is able to store in its roots and trunk during the fall. This reduces the trees vigor the following spring, since spring growth is the result of stored food and energy.

You won’t need to worry about summer pruning right now, we’ll deal with that in about six or eight months. In the meantime, we are approaching the optimum time to prune your fruit trees in order to get larger fruits and bigger crops. Next week I’ll give you some specific pruning instructions for our most common deciduous fruit trees.

Questions from Readers

Question: When should I plant my strawberries?

Marian, Laguna Beach

Although the majority of home gardeners seem to plant strawberries in spring, the best time to plant strawberries is in fall. Did you notice that the commercial strawberry fields scattered around the county have already planted their crops for next year? A month or two ago would have been ideal, but it’s still not too late. Because of the larger root system and the winter chill that fall planted strawberries receive, they produce way more fruit than those planted in the spring. Hurry, this weekend, Marian!

Ron Vanderhoff is the Nursery Manager at Roger’s Gardens, Corona del Mar.