Crepe myrtle shrubs and trees are in full bloom this time of year. I’ve seen some nice specimens in local landscapes as well as at the old airport, in some cemeteries and in Hilo parking lots. The colorful flower clusters are easy to spot. Beyond the flowers, this plant has many qualities that make it a good choice for Kona gardens.
The Crepe Myrtle (Lythraceae) family has around 580 species but the best known here in Hawaii are those in the Lagerstroemia genus. In the 1700s, Linneas named this genus for his friend, Swedish naturalist M. von Lagerstroem. The common name we use is easier to explain since it was likely derived from the crepe-like appearance of the plant’s flower.
The smaller variety, Lagerstroemia indica, is often grown as a shrub but can also be grown as a small tree, determining at less than thirty feet. In either form this crepe myrtle makes a lovely specimen plant and can also be used as a hedging or screening plant. The larger Lagerstroemia speciosa is often referred to as the giant crepe myrtle. In ideal conditions, it can grow to fifty feet tall.
Both plants produce dense clusters of flowers that are each nearly an inch across with crinkly petals. I have seen several in a deep magenta or mauve color but also some with lavender or pink flowers. Varieties in deep purple and even white are also available. The colored buds that appear early in summer before flowering are also very attractive.
Native to a huge swath of Asia from southern China and Southeast Asia to Japan, this plant is now cultivated in warm or tropical areas throughout the world. Numerous cultivars have been developed, giving gardeners lots of choices. Many hybrids have resulted from crossing L.indica with the Japanese crepe myrtle L.fauriei. The results differ in flower color, mature size and pest resistance.
In addition to the summer flower show, some crepe myrtle varieties have an attractive peeling bark with a smooth surface of tans and greys underneath. This feature adds to the plant’s attractive appearance.
The dark green leaves of the crepe myrtle offer a nice contract to her flowers. In the fall, many crepe myrtle plants lose their leaves, however. In some varieties, the leaves will turn bright colors before they fall. This is just another attractive feature of this plant.
Crepe myrtles grow best in full sun in soil that drains well. They are drought tolerant once established and will flower best in the hottest months of the year. When grown in shade or cooler temperatures, they will produce smaller and fewer flowers.
The plants grow fairly quickly and can become a bit leggy if not pruned occasionally. Since flowering takes place on new growth, a heavy pruning following one season’s flowers will encourage increased flowering the following season.
Beyond some pruning, crepe myrtles require little maintenance. They can grow well in nutrient poor soil and do not need much fertilizing. In fact, over fertilizing can cause a reduction in flower production.
Though many of these plants have some disease resistance, mildew can be a problem at upper elevations that are cooler and wetter. Hot sun and good air circulation in the branches can prevent mildew growth. Though not usually attractive to insects, the Chinese rose beetle can be a problem when the plants are young. Surrounding the plants with small solar lights that go on after sunset can help deter these guys.
The best way to propagate crepe myrtle is by cuttings. Remove a six-inch piece from the end of a healthy branch that is about the diameter of a pencil. Choose a branch that is soft and flexible rather than woody. Dip the cutting in rooting hormone and insert it at least two inches deep in a container that contains a moist, well-draining mix. A mix of 50% vermiculite and 50% perlite works well.
Remove most of the leaves from the branch. Place the cutting in a warm area out of direct sunlight and keep the medium moist but not wet. Within a month the cutting should from roots.
Once you see the plant putting out new leaves, you can test root strength by pulling gently on the cutting. If you feel some resistance, it has most likely formed roots and is ready for planting into a larger pot or in a well-protected spot in your garden.
Call local nurseries or check the big box stores for crepe myrtle plants. If you can’t find them for sale and are having trouble finding a plant for cuttings, call Margo to see if she can help. She’s at 808-640-9191. If you can find one and get it in the ground this season, you will likely have a lovely flowering plant by this time next year.
Gardening events
Saturdays: Work Day at Amy Greenwell Garden, from 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Come with a mask and be prepared to practice social distancing. Volunteers can help with garden maintenance and are invited to bring a brown bag lunch. Water and snacks provided.
Now: CLR resistant coffee trees available for pre-order. Ungrafted $10 / Grafted $15. Email Andrea at andreak@hawaii.edu to express interest in the Catimor hybrids. Not available for propagation purposes.
Save these dates
Thursday, August 15: Worker Protection Standard Webinar, 9 to 10:30 a.m. For farm and ranch owners, managers and their workers who handle or apply pesticides. To receive the Zoom link and attendance form, go to https://www.hawaiicoffeeed.com/wps or contact Matt at 808-322-0164 at least 2 days prior to the webinar.
Saturday, Aug. 17: Native Hawaiian Plant Sale, 9 a.m. to 1 p.m. at Amy Greenwell Ethnobotanical Garden in Captain Cook across from the Manago Hotel. Several important pollinators will be featured.
Thursday, Aug. 22: Waimea Service Center Resource Workshop, from 6 to 8 p.m. at Kuhio Hale Farmers Market, 64-756 Mamalahoa Highway, Waimea. Free workshop to learn about USDA programs and practices.
Friday, Saturday and Sunday, Oct. 4-6: 34th Annual Hawaii Tropical Fruit Growers International Conference at the Maui Food Innovation Center and farm visits. Talk by Dr. Johathan Crane from the Tropical Research and Education Center at the University of Florida plus workshops. For more information as the event gets closer go to htfg.org.
Farmer direct markets
(Check websites for the latest hours and online markets)
Wednesday and Friday: Ho’oulu Farmers Market, 9 a.m. to 2 p.m. at Sheraton Kona Resort at Keauhou Bay
Saturday: Keauhou Farmers Market, 8 a.m. to noon at Keauhou Shopping Center; Kamuela Farmer’s Market, 7:30 a.m. to noon at Pukalani Stables; Waimea Town Market, 7:30 a.m. to noon at the Parker School in central Waimea; Waimea Homestead Farmers Market, from 7:30 a.m. to noon at the Waimea middle and elementary school playground.
Sunday: Pure Kona Green Market, 9 a.m. – 2 p.m. at Amy Greenwell Garden in Captain Cook; Hamakua Harvest, 9 a.m. to 2 p.m. at Hwy 19 and Mamane Street in Honokaa.
Plant advice lines
Anytime: konamg@hawaii.edu
Tuesdays and Thursdays: 9 a.m. to noon at UH-CES in Kainaliu – 322-4893 or walk in
Mon., Tues. and Fri: 9 a.m. to noon at UH CES at Konohana in Hilo 981-5199 or himga@hawaii.edu
Diana Duff is a plant adviser, educator and consultant living part time in Kona.
