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Monday - July 25, 2011

From: Littlestown, PA
Region: Mid-Atlantic
Topic: Non-Natives, Diseases and Disorders, Watering
Title: Shy blooming non-native Crape Myrtle, in Littlestown Pennsylvania
Answered by: Leslie Uppinghouse


My Crape myrtle has been planted about three years, and reached a height of about 4'. It blooms late July and for the past two years, has only had one or two blooms on it. I have a lot of buds which have turned brown. What should I be doing?


Crape myrtle is the common name for Lagerstroemia indica which is native to temperate and tropical Asia. The Lady Bird Johnson Wildflower Center is dedicated to the care and propagation of plants native not only to North America but to the area in which they grow naturally, which places this out of our range of expertise. 

Crape myrtles are commonly planted throughout the United States. They have done their best to adapt to many areas of the country. They are funny trees, they love sun and they love the heat, if planted in the right area with enough sun, they do ok. Breeders have fooled around with the varieties to keep them happier here. To keep them from susceptibility to powdery mildew outbreaks and from suffering through times of drought. The bottom line is however, that Pennsylvania isn't anywhere near Asia and these trees know it.

Why your buds are not opening up, could be linked to a number of explanations. The key to success, is age with these trees. If you can help your little Crape to grow up and adjust to your climate without overwatering, then you deserve some blooms. Once the tree is old enough and toughens up, you should see a visibly grander display of flowers but it is going to take some care and time.

Crape myrtles don't like frequent irrigation. They like moist hot climates but respond poorly to overwatering. This sounds like a subtle distinction but it isn't. Water from the sky is different from water underground and water that has been treated is even trickier. If your tree is brown at the tips of the leaves and buds, at the end of the branches, then you might have a blight that is caused by fungus. Copper fungicide could be used if that's the case. The treatment would need to be repeated and you would have to be careful not to water from above with irrigation water. You would also want to prune carefully the area that has been effected. If you do this, then make sure to wipe your pruner between cuts with bleach so as not to spread the disease. If you have any mulch around the base of the tree, remove it and give it new, clean mulch. The spores of the fungus would be in the mulch as well as on the effected leaves and buds. Before you use any kind of spray treatment, take a sprig of the effected tree to your local extension office, to make sure the diagnosis is accurate. Here is a link to the Penn State extension site which was listed for Gettysburg which would be close to Littlestown. 

Crape myrtles need lots of sun and heat to bloom. Right now you have the heat, but you also had a pretty cold winter, so this might be delaying the blooms. If your tree is having more than four hours of partial shade, then this could be why you have not had many blooms in the past and you are not seeing any this year. They want full blown sun. They love the sun so much that if the tree is too bushy and the light can't get in between the branches, they will sometimes pout, and hardly bloom at all. If that's the case, you can prune out some of the middle branches giving them good air and light between the branches.

Over fertilization that is nitrogen heavy will prevent blooming, by focusing the plants energy on leaf production instead. Lawn fertilizers have a lot of nitrogen, add a little bonemeal to the soil around the tree to help out with some phosphorus. 

Crapes grow quickly, with new growth in the spring and budding out in the summer. It depends on the seasonal conditions as to when those buds open up. In times of drought or late season heat you might see Crape myrtles blooming in late summer or even early fall, so don't give up on your buds just yet.

Last but not least there is the dreaded Japanese beetle. These beetles eat bloom buds like candy. If you are not sure if you have beetles, take a big bowl of water and hold it under a branch. Tap that branch hard with your hand, if a beetle falls into the water cry for a while and then run down to your local nursery and find a good environmentally safe solution to treat them. You do not want to spray anything that might kill off your beneficial bugs that are working hard for you, to keep other unwanted pests away.

Sometimes it won't be just one reason a plant isn't performing its best and with non-native species it usually is a combination of issues. Pay attention to the sunlight in the area, and try to keep a diary of your weather year by year with notes on if and when your tree blooms. Give it some time and we bet if you have the right light your Crape will bloom a little more as it grows older.




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