Horticulture Hotline 03/26/18
By Bill Lamson-Scribner
The question about pruning Crepe Myrtles and other plants
seem to top the list of questions for this week. The butchers are out there! The
time is now for getting in your soil test, so you can amend the soil by spring
time. Do you have any disease prone plants (roses, etc.) that could benefit
from a little sanitation? What is the population of moles in the Lowcountry?
What is the population of moles in your yard? Have you applied Neem Oil for
overwintering insects and disease?
Crepe Myrtles are the most abused tree in the landscape.
Since they bloom on new growth, someone “topped” them a while back and notice
the flush of new growth and the prolific blooms. These heavy blooms are
supported by wimpy 18 – 24 sprouts that just developed that growing season.
When it rains, the bloom catches water and becomes even heavier. The bloom will
hang down and eventually the wimpy new growth supporting the bloom will split
off tree leaving an open wound for insects and disease.
Instead of “topping” the tree to increase blooms, a good
fertility program will accomplish the same thing without ruining the beautiful
natural branch structure of the tree. A soil test and program can guide you to
the right fertilizer for your tree. Have you ever seen a Crepe Myrtle in the
winter when the leaves are gone, and sense the tree’s embarrassment, like a dog
with the cone on its head? A tree that has been “topped” is standing there
naked of any foliage with these big nasty swollen knobs at the end of the
branch, like huge warts. The tree that is pruned correctly is standing there
naked and proud, like a nude Greek Statue.
The correct pruning for a Crepe Myrtle involves removing
dead limbs and crossing limbs. Any limbs growing toward the middle of the tree
are good candidates for removal. If a limb is growing to the outside of the
tree let it be. Opening up the center some for sunlight penetration and air
movement is always a good idea to help prevent disease. Sometimes Crepe
Myrtles, being a multi-trunk tree, can have too many canes growing from the
ground, and one of these needs to be removed. Removing these canes is best done
while the tree is very young; however, you can prune these canes out once the
tree is older.
There is a very rare occasion that a landscape designer
orders that a tree should be topped. Under certain circumstances usually
involving safety concerns or visibility concerns a designer will recommend
keeping the tree at a certain height. When I worked on Hilton Head, we had a
safety situation by a guard gate that required us to “top” the Crepe Myrtles;
however, we did not “top” the other Crepe Myrtles in the project. Some
businesses want their sign to be seen, and Citadel Mall is practicing
pollarding, a type of severe pruning that the Crepe Myrtle can tolerate.
Now days, Crepe Myrtles are available in all different sizes
from 3 feet to 30 feet, so planting the right one to fit the scale of your
landscape is crucial. Much of this “topping” can be avoided with the proper
plant selection and proper fertility. Whoever is planting the tree (or any
plant) should look at its mature height and spread. Then plant the right plant
for the space.
If you live in Mt. Pleasant, learn the local ordinances
because they have laws about the proper pruning of Crepe Myrtles.
After you prune your Crepe Myrtle properly, now is the
perfect time to add Cotton Burr Compost as a mulch, SeaHume as a biostimulant
and minor nutrient treasure chest, and a tree and shrub drench for insect
protection.
Spring is coming. Preemerge?
