Our landscape trees rarely die of old age. Usually there is something we have done or failed to have done that shortens the lifespan of our landscape trees. Sometimes it is easy to forget that they are living things that need certain conditions to be met in order to thrive. The science of cultivating a healthy tree often gets overlooked for the sake of convenience. Hopefully by avoiding some of the mistakes mentioned below we can do a better job of taking care of our tree canopy.
1. Do not give them enough water after planting.
A tree in the nursery gets watered several times a day with a dedicated source of water that goes right into the container. In order to become established in the landscape a newly planted tree needs water directly applied to the rootball. The same irrigation you provide to your lawn through sprinklers is not enough. At the minimum a newly planted tree needs 2-3 gallons applied for each inch of trunk diameter. For the typical 2-inch diameter tree that would be 4 to 6 gallons every day for a month, every other day for three months, and then every week until it is established. The larger the tree, the longer the irrigation periods will be
2. Plant your tree the same depth as it was in the container.
Trees should be planted where the root flare is slightly higher than the surrounding soil. The worst mistake is to plant your tree deeper than it was in the container. A wise forester I know came up with this saying. If you can remember…” plant it high, and it won’t die” your tree will be in good shape.
3. Don’t cut the roots circling the container when you plant your tree
The biggest drawback to growing trees in containers is the fact that when roots come in contact with the edges of the container, they are deflected to circle the rootball. Unless these roots are severed, they will continue to circle and fail to expand out to the surrounding soil. Removing these circling roots at the point where they come in contact with the container improves the chance that your tree will establish in the space you have provided and develop a good root system.
4. Plant a large maturing tree in a small space.
We see this all the time with large maturing trees such as live oaks planted in small front yards or even the four-foot space between the street and the sidewalk. On average large maturing trees need at least 900 square feet or more of space to acquire enough water and nutrients and anchor themselves properly. Medium trees need 400 square feet of growing space and small trees need at least 100 square feet of rooting area. If you do not have the space find a smaller maturing tree that will still meet your objectives.
5. Pile mulch, soil, or leaves up around the base of the tree.
Mulch, fill, leaves should not be placed where it is contacting the trunk of trees. Roots can be submerged under an inch or two of mulch, but trunks should not have anything touching that can hold moisture keeping the bark damp. Trunks need to be kept clean and dry. Take a walk through your local nature preserve and observe the trees. The root flare that is the transition between the trunk and the roots is plainly visible. This should be the same in your landscape. There is a term for when mulch is piled too high on a tree. It is called a “mulch volcano”. In addition to causing decay in the trunks of trees by holding moisture, mulch volcanoes also promote roots that grow up out of the soil wrapping themselves round the tree trunks. These girdling roots can choke a tree and keep it from thriving.
6. Thin out the canopy of the tree by removing interior branches and water sprouts
The interesting thing about science is that it is always improving how we do things. Things we have always a certain way I the past may not the right thing to do now. Early on in my career I used to recommend to residents that they thin out the canopy so that wind blows through it instead of against it. After the active 2004 hurricane season the University of Florida started studying the best way to prune a tree for wind tolerance. It was determined that thinning out the interior of the canopy actually increased the likelihood of tree damage rather than decrease it. What we were doing was transferring most of the weight to the ends of the branches making them more likely to break. Over thinning the canopy in a practice called lions-tailing is now considered a practice that reduces the wind tolerance of a tree. Reducing the length of branches appropriately through a type of pruning cut called a “reduction cut” as well as leaving interior branches is the proper method to increase the wind tolerance of landscape trees.
7) Hurricane pruning of palms.
Removing the foliage of a palm to where the only fronds that are left are sticking straight up is commonly called hurricane pruning. It is funny (not really) that this type of pruning actually makes your palm weaker. The green fronds are where food is produced in the tree. Over time, the skinnier trunk that forms when the palm is put on a diet when too much of its food source is removed becomes more likely to sway and break in the wind. Typically, only brown dead leaves should be removed when pruning palms. If that is not practical, palms should be pruned NO higher than 9 o’clock, and 3 o’clock as on a clock face. Some literature describes it as no higher than horizontal.
By taking care of our trees cultivating them properly, we can be confident that they will live long and productive lives. For timely research-based information to help solve any of your landscape questions, go to the University of Florida/IFAS Extension’s new “Ask IFAS” site at https://edis.ifas.ufl.edu/ and simply type the subject you want to know more about.