Saturday, January 2, 2010

Dormant Pruning: Keep It Simple.

Dormant Pruning: Keep It Simple.

"The best time to prune fruit trees is when you have enough time to finish the job, anywhere between November through March." —Oregon State University

I have written about dormant pruning before. Lots of descriptions, principles, background information. But every now and then I get someone who wants it plain and simple. No embellishments. How-to-prune in 1000 words or less. Short declarative sentences. Ok.

These recommendations are for deciduous fruit trees (and vines). Citrus are evergreen subtropicals, best pruned when there is no risk of frost damage.

Basic principles:
  • Proper pruning enhances trees; improper pruning endangers them.
  • Remember the goals (different than for shade trees!): control the structure and size of the tree, control the amount of fruit.
  • Look at where the tree produces fruit: all along the branches on last summer's wood, or on short 'spurs' on older wood.
  • Most pruning is a combination of thinning some branches, shortening others.

Why prune fruit trees?
To improve the structure of the tree, to control the size of the tree for easier harvest, and to reduce fruit production of larger-fruited types.

When? Winter (between December and the end of February is best).

  • Remove diseased, dead, crossing or rubbing branches.
  • Reduce the height of the tree.
  • Remove lots of fruiting wood on heavy-bearing trees.
  • Train young trees: select what will be the permanent branches, and prune out the center of the tree if you want a more open habit.
  • Summer (after mid-July):
  • Control size by cutting back new growth -- like a hedge if you like -- to keep the tree within picking height.

How do I prune specific types of fruit trees?
Keep in mind the principles: better structure, smaller size, control fruit. Know where each type produces fruit.
Regardless of the type, always begin by removing dead, diseased, crossing, rubbing branches, and strongly upright shoots (suckers).

Severe pruning required every year:
  • Peaches, nectarines.
Hint: Look for the red branches with fuzzy buds. That's where the fruit will be.

Fruit is produced all along last summer's growth (see illustration below). On peaches and nectarines, last year's growth is conveniently red, older wood is grey. Thin out about 50% of what grew last year, and shorten the remainder by 50%. Yes, reduce fruiting wood by 75% -- or more!

  • Plums, pluots.
Produce on spurs AND along last summer's growth. May seriously overproduce. Thin out the many suckers these produce (strong upright shoots), cut back last summer's growth at least 50%. You'll get lots of fruit no matter what you do.

Moderate pruning required most years:
  • Apricots, apples, pears, and Asian pears.
Prune to make the trees shorter.
Cut out strongly upright branches, thin these trees by about 25%.
Fruit is on short spurs which grow on 3 - 4 year old branches.
Apricot spurs (below) produce for a few years, the others fruit for many years. Older trees may produce far more fruit than you want. It's ok to thin more heavily as the trees get older.

Light or no pruning required:
  • Sweet cherries.
Prune to shorten if you want, but they can be beautiful large trees if you prefer (the birds will thank you). Fruit on spurs which produce for many years. Don't prune severely. Pie (sour) cherries have a graceful, spreading habit and only need light thinning.

  • Persimmons and figs.
Persimmons: no pruning required except to thin crossing branches. Strong wood can hold large crops, and they are very ornamental trees. Sometimes pruned for size control.
Figs: prune severely for size control (you'll still get plenty of fruit), or allow them to become big tropical-looking trees -- and get even more fruit. Your choice.

  • Pomegranates, jujubes, and quince.
Large shrubs don't need to be pruned at all. Can be trained into small, multi-trunk trees (keep removing suckers), or sheared as a hedge, or topped for size control. You'll still get more fruit than you can use!

  • Nut trees.
Thin lightly and allow them to grow as big as they want, since we harvest off the ground. Pecans need careful training for safe branch structure, and, like walnuts, are very big trees. Neither takes well to size control. Almonds are good small back yard trees: thin lightly if at all.

Other fruit plants.
  • Grape vines.
Fruit on one-year old branches.
Thin out most (75% or more) of the long branches that grew last summer.
Shorten the other branches to about 3 ­ 4 buds -- unless you have Thompson Seedless. For that variety, count out and cut to about 8 buds or more. If you don't know what you have, prune like Thompson Seedless.
Generally 30-50 buds are left per mature vine regardless of the pruning system.

  • Kiwi vines.
Fruit on one-year old branches, like grapes.
Cut out more than half of last year's growth and shorten up the rest to 3 ­ 4 buds. Prune vigorous, tangled growth in summer if necessary.

  • Berries.
Caneberries: blackberries, Boysen, Olallie, Marion, Logan, etc.
What grew last summer fruits this spring, and never fruits again. Remove branches that have fruited, leaving the new ones. It's easier to tell them apart in the summer or fall, but the pruning can be done anytime. Winter is a handy time to tie up the sprawling vines.

Published information is very confusing. Some produce in spring, some in summer, some both. Most don't produce well enough here to bother, frankly, but in general they are thinned to remove weak canes in the spring, sometimes are headed at that time, and then canes which have fruited are removed when they're done (usually in late summer).

Fruit is produced on year-old wood on attractive shrubs. Pruning is similar to roses. Thin out old shoots from the base, leaving 4 ­ 6 of the newest ones. Shorten some of the remaining branches by a foot or so.

Written for the Davis Enterprise, Jan. 26, 2006

No comments:

Post a Comment