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Tuesday, October 30, 2012

When and How Do You Prune Pine Trees?

Q. I know you prune fruit trees when they're dormant, but what about pine trees and other conifers? Mine get a couple of growth spurts a year and I didn't know if there was a "better" time for pruning.

Pine tree candles.
A. Normally the decision to prune involves two pieces of information; when does it start growing for the season and if it has flowers or fruit that we value, we would normally prune after it finishes flowering or fruiting.

            In the case of pine trees that grow well in the temperate climates (those climates which have distinctive four seasons) we always default to the winter season for major pruning. So the normal time to prune nearly everything is during the winter months.

            In the case of pine trees that grow in temperate climates this is also the case. If we were talking about tropical pine trees (not in Las Vegas) then we would time or pruning to its normal season for dormancy which is the dry season.

Pine tree thinning to reduce blowover from high winds
and the subsequent loss of branch taper or caliper.
This practice can lead to branch breakage which it did
(see my other post on this blog). It is best to selectively
remove entire branches rather than lateral branches along
a major branch.
            An exception to this is a technique of pruning pine trees that encourages dwarfing and increased density of the canopy. This is a technique called “candling”. Candling is done when the new growth coming from the ends of the branches is about 4 to 6 inches long. This new growth as it is emerging resembles a candle.

            Candling is done with your fingers and simply breaks the new growth as it is emerging in the spring. Usually we break the candle in half, we never cut the candle. Cutting the candle with a pruning shears causes the tips of the needles, which are cut in the process, to turn brown. This is unsightly.

            By breaking the candle in half we cause the buds at the base of the candle to grow and instead of getting one branch to continue growing we may get three or four. These three or four new shoots will not grow as long as the single shoot we removed.

Pine tree thinned to reduce "sail" on the canopy resulting
several years later in caliper loss in branch and subsequent
limb breakage (bottom center).
            This new growth remains more compact. Having three or four new shoots instead of a single shoot increases the canopy density.

A recent problem has developed in pine tree pruning. This is the idea of "thinning" the pine tree canopy to prevent blowover. In some cases on shallow soils with shallow, frequent irrigations, pine trees might not have enough root structure to support the tree in heavy winds. With gale force winds these trees blowover damaging property.

One recent practice by arborists has been to offer "thinning" of the canopy by removal of branches thus reducing the "sail" effect of the canopy during high winds. This sounds good but you have to be careful WHICH branches are removed in the pruning process. If lateral or side branches are removed along a stem or branch, this might cause a decrease in the strength of this branch due to a future loss of branch "taper" or caliper. This decrease in strength due to a loss of branch taper can lead to breakage and dropping of these weak branches.


  1. I have a pine tree in front of my home, and have had this same question. The tree needs to be pruned soon, but I don't know how, or when the best time to do it is. Very good to know that I should wait until the tree starts flowering for the year. Normally for my tree that is right about now. Once I see it start flowering I will get right on that pruning. Thanks for the great information. http://www.heritagetreecare.com.au/corrective-and-formative-prunning/

    1. It is good to see someone in the industry comment. I hope I did not mislead in this article. I would remove major limbs only during the winter season with pine in the desert. Light pruning could be done anytime. For increasing the density of pine we would break the "candles" when new growth is occurring. Break the candles by hand, do not cut them with a shears or the needles will brown on the tips. Candles are the new growth coming from the tips of the branches. Called candles because this new growth looks like candles as these buds are expanding. Thinning of the tree to prevent them from blowing over should be by selective limb removal, not removing small branches along limbs. Removal of small branches can lead to large limbs breaking during high winds because the limbs will no longer get larger in diameter and lack the taper needed for strength.

  2. When to prune a tree is a tough decision as the further growth depend on it. Proper pruning helps prevent decay and reduce pest and disease problems while improper pruning, such as topping, can cause severe decay, hazardous branch failures, or even death. So have a thorough knowledge of your tree and when to prune it.

  3. Thanks for the comments! Constructive coments from the Pros are welcome and encouraged!

  4. The State department trimmed my white pines along side the road in front of my property. They cut off every single limb on the side facing the road. Will these limbs grow back?

    1. Limbs will not grow back in most cases. There are some pine trees that will "sucker" from the trunk after limbs die. These are pines that will tolerate fire damage for instance. An example is Pinus roxburghii or Chir pine. But this would take a dozen years. For the most part, once removed they are gone.

  5. My neighbor has a pine tree with limbs that cross our fence and are depriving my orange tree of sunlight at times of the year. Real estate law allows me to trim the branches along the property line. If do trim them will it kill the rest of the branch or damage the tree in any other way?

    1. No, it will not kill the tree. It might be aesthetically not pleasing if done poorly. Try to remove the entire limb at the trunk if possible. Otherwise, if you cut a limb back that has no needles on it, the entire limb will die.

  6. My mom got my dad pine trees for Father's Day and we are looking to know how to maintain them. It is good to know that for pine trees that grow well in temperate climates, it is good to default to the winter season for major pruning. I will be sure to inform my parents that they should start to think about pruning in the early winter months. https://greenlifetreecare.com/