Crape Myrtle Can Be Grown in Desert Soils

Q. I
planted this crepe myrtle the first of May. I recently noticed leaf curling and
now the brown edges. I’m watering with 6 “ inline tube emitters every other day
for 20 min. It’s located in a very hot spot in a corner with south and west facing
walls. Any advice would be appreciated.

Crape myrtle newly planted and growing in a raised bed.

A. The browning along the leaf edges either means though tree
is not getting enough water or it is being watered too often. The crêpe myrtle
will not like hot locations. It doesn’t like hot locations unless you are a
very good gardener and can manage that heat and water it needs.

I certainly wouldn’t water more often than every other day.
I worry a little bit about two things; is the soil staying too wet between
irrigations and secondly is the water getting deep enough when you are
watering. 20 minutes of watering doesn’t tell me much. I drink 16 ounces of
coffee in 1 ½ minutes. I like coffee when it’s hot. Some other people they can
sip on this coffee for one hour. So, 20 minutes doesn’t mean much to me. A
crêpe myrtle that size needs about 10 gallons of water. It can get it in 20
minutes or one hour. It doesn’t matter.

Crape myrtle watered with a basin and bubbler, fertilized once a year and using EDDHA iron chelate as its iron source, No organics added to the soil.

I noticed you have what looks like vinca or periwinkle
planted with the crêpe myrtle. That is a no no. Vinca or periwinkle has roots
that are shallow growing to about six or 8 inches deep. It likes to get
frequent watering. The tree on the other hand has roots that are as deep as 18
inches. It likes to get water less often than the vinca but more applied each
time. Unless you are a very good gardener and can manage the water between the
two the mixing of these two plants together can cause problems in watering. I
suspect that’s what you’re seeing. Other deeper rooted flowering plants like
rosemary would be a better choice since it has deeper roots and a more similar
watering regime.

What to do? 

I am not sure how much water that laser tubing
is delivering in 20 minutes. The water for the tree should be applied so that
it penetrates the soil each time to a depth of about 18 inches. Then the idea
is to hold off on watering again until the soil begins drying in the top few
inches. That might be one day or it might be two days I’m not sure. An
inexpensive soil moisture meter like for house plants would tell you that. 

Inexpensive soil moisture meter used for monitoring irrigations. Push it in three or four inches in several different locations.

Push
it into the soil in three or four locations about three or 4 inches deep and
don’t water again until it reads Midway or about five on the 10 point scale. The
periwinkle are vinca will drive your watering cycle since they are more shallow
rooted.

The other problem you’re going to have with crêpe myrtle during
the summer months is its location. As you pointed out it’s very hot in that
spot. The crêpe myrtle will improve and looks in October and November but it
will not like it there during the heat. The most successful locations for crêpe
myrtle in Las Vegas has been on the east or north sides of homes where it’s a
bit cooler.