In our area we have a narrow window of time for the optimal pruning of citrus trees. We like to prune them after all danger of frost is past. If we prune them and they freeze, more damage can occur than if they were left unpruned. We also like to trim them early enough that new leaves can form to provide shade for branches near the top of the tree if we need to take more than we want due to branch structure problems (or frost damage!). I explained previously how to remove a branch here - now, which branch should be removed? I plan to explain that in this post.
Citrus trees have trunks and large branches that are sensitive to the sun. Have you seen citrus trees with their trunks painted white? That is for sun protection when too many of the lower branches have been removed. We like to use a brown tree paint in these situations as it looks much more natural. Properly trimmed, citrus trees should have branches down to within 12″-18″ of the ground. The grove we worked on today had the lower branches a little low to the ground (wherever the rabbits hadn’t eaten them higher – actually the rabbits almost trim them to the perfect height, deer trim them too high!). Here is a photo of the grove:
The first thing I do when I start trimming a citrus is to look at the trunk. All citrus trees are grafted. The nurseries use a rootstock that grows vigorously but produces terrible, sour fruit! They graft on whatever variety of citrus is desired, such as Arizona Sweet Orange, Ruby Red Grapefruit, etc. If you were to take one of the seeds from a named variety of citrus fruit and grow it, the resulting tree would produce fruit that might be very different than the one it came from. That is why citrus are always grafted (actually most other kinds of fruit trees are grafted as well).
When you look at the trunk, are there any branches coming off just above ground level? These could be branches from the rootstock (below the graft) which would produce terrible fruit. These branches need to be removed. Also, even if the branches are above the graft, they usually grow straight up through the center of the tree as a “sucker” which also should be removed. Here is a picture of one of the tree trunks in the grove:
Removing these branches usually opens up the middle and top of the tree considerably. After they are gone it is possible to see what else needs to be taken off.
We usually have to work our way under the tree, sometimes laying on our backs (hope there are no cactus!). An automotive repair-type scooter with all-terrain tires would be a great invention for this! After you are under the tree, you can look up and see what the middle is like. Here is the starting point:
The idea is to open up the inside of the tree. If it is a larger tree, you should be able to stand up inside it. The outer canopy is left mostly intact to provide shade for the trunk and major branches. Small breaks in the canopy are no problem and can actually be desirable. Here is a photo of the inside of the finished tree:
After the inside of the tree is opened up, we look around the outside. We remove any suckers that originated from higher up (from the trunk or branches). We also remove any frost damaged branches from the outside of the tree. There are often branches that stick way up above the top of the otherwise neat looking tree (especially on lemon trees) – these can be cut back (properly, to a fork) to improve the appearance.
We are trying to finish all our citrus trimming this week. We should have enough time before the really hot weather hits for any holes in the canopy to fill in and provide shade to the sensitive branches. The trees are in flower right now! Any branches we remove, or flowers we knock off will obviously not produce any fruit. Usually a few less oranges or grapefruits will not be a problem! Thinning the fruit now (or later) may result in the remaining fruit being better(size and quality).
One more word about citrus tree care – fertilization! I like Arizona’s Best fertilizer. Their Citrus Food calls for applications in February, late May, and the later part of August or the first part of September (the earlier dates in the fall would be better for colder climates). Application rates are on the package. We definitely recommend using this product, as directed!