I have done a couple of lectures the past few weeks and have been asked about pruning Citrus, both there and at work lately. So, I guess it is a good time to address this situation.
When should you prune Citrus, How should you prune Citrus, SHOULD I prune Citrus?
These are usually the questions asked.
I usually don't recommend pruning Citrus trees, you would be cutting fruit off if you do. However, there are times when it is or might be necessary.
Let's start at the beginning.
Unlike most other fruit trees, Citrus trees do not require pruning to keep them productive. On their own they will develop an attractive shape without any pruning.
Young trees will often produce very vigorous shoots that will give the tree an unkempt, out of balance feel. These shoots can be cut back to maintain a more uniform shape.
If you have a grafted tree, anything below the graft line should be cut off. The graft line will appear as a dog leg, maybe 3-6 inches above the soil. This is where the Scion and Rootstock meet. If the sprouts are below the graft, that is the rootstock trying to come back. Chances are, this will produce fruit that you really wouldn't care to eat.
There are some theories out there that any vigorous growers, usually Lemons, can be cut back about 20% to 30% every couple years. this will keep the fruit in a range that is much easier to harvest.
Keeping the centers of Citrus trees open, think vase shape, will help with the health of the tree. To do this, you will want to remove any crossing branches, dead branches or by selectively thinning branches. This will allow sunlight into the center of the tree and help keep inner portions productive. This will also increase air flow, decreasing the chance of fungus and disease.
Occasionally, you may need to prune a leggy tree. This will be caused by inadequate light or grown indoors. You can cut this back to force branching and create more bushiness.
Hard freezes will occasionally come and harm your Citrus tree. You will want to cut any dead or apparently dead wood out right away. Well Don't!
Wait until after the first good flush of Spring growth. I know it looks ugly, but you can actually do more harm and actually slow down the trees recovery. There is research out of Florida that has found that trees pruned after the first flush of growth, actually recover more quickly and grew more vigorously than those pruned immediately after the freeze event.
Citrus trees can also be cut back if you planted them in the wrong place to begin with. I would recommend moving the tree first, but if that is not possible, an occasional clipping to keep it out of the sidewalk or driveway is not detrimental to the tree. Under normal conditions, light pruning will not drastically reduce your fruit crop. A heavy pruning, such as a quarter of the tree or more, will reduce it accordingly.
Well, there you have some reasons why you would want to prune a Citrus tree. There are probably others I haven't listed. The next question inevitably is always, WHEN, can I prune?
Citrus can generally be pruned at any time, but it is best to do it just before it blooms or just after fruit set. The tree will adjust itself.
Avoid pruning during late Summer to early Fall if you can. Pruning during this time usually stimulates vigorous new growth. If you are planning on protecting your trees during the Winter, like moving it into a greenhouse, this is okay. If your trees are planted in the ground, this can cause problems. The new growth that a late pruning stimulates will not have enough time to harden off before Winter sets in. This will greatly increase the chances of frost damage.
If you are pruning late in the year, you can also have the problem of exposing the fruit and bark to too much sun suddenly and sunburning it. Bark can be highly sensitive to sunburn. If it is severely burned, it will die and cause a girdling of the tree.
I hope this helps in your quest to give your Citrus tree a haircut. Personally, I very seldom prune mine. Occasionally I will limb a tree up a little, so I can get to the soil to feed and water it easier, but other than that, I let them go to town.