Lagerstroemia indica 'Whit X' DOUBLE DYNAMITE^®

Crape myrtle is a flowering shrub or small tree from China. It was first introduced to the USA and the UK in the 18th century. The original plant lagerstroemia indica is too tender and not too pretty so breeders were working on further hybridization and the most attractive varieties available now are believed to be results of crossing with l.speciosa and l.fauriei. Far more important news for us is the fact that among those finished plants were selected others that survived lower temperatures than what was common in the areas of natural habitat so we have a few myrtles that can grow even in our climate. Some were selections, other consequent hybrids.

Carl Whitcomb is one of the most important breeders of crepe myrtles with exceptional features, of which we particularly appreciate increased hardiness. He owns and runs a research station Lacebark Inc. in Stillwater in Oklahoma, USA, whose USDA zone is the same as warmer parts of Central Europe (7a), which offers great potential for our climate. He has been breeding crepe myrtles for over 40 years, and his very first patented success named ‘Whit I’ dates back to 1996. He created a series called Oklahoma Tough^® which manifests the hardiness of his plants – it often reaches as low as -25 °C (root-hardy). He does not exclusively crossbreed hybrid varieties, but mostly proven varieties of the botanical species l. indica using ethyl methane sulfonic acid methyl ester (EMS), which can penetrate DNA and cause mutations, resulting in significant quality changes in the new generations. Carl Whitcomb focused on selecting those with, in addition to improved beauty, better health and flower sterility which makes possible repeat flowering without exhausting the plant with seed production.

DOUBLE DYNAMITE^® is an improved crepe myrtle variety of DYNAMITE^® from 2014. It bears some of the reddest flowers on the background of dark maroon foliage. It belongs to the Play It Again^® series which comprises of varieties with double flowering on the same panicle and in a few cases also dark foliage as a bonus. The inflorescence of DOUBLE DYNAMITE^® is a large (30x20 cm), upright panicles. Individual flowers are deep cherry red and open one by one from late July or early August (depending on summer quality). Once the first flush is almost over, new flower buds appear on the same panicle and, since they are sterile and do not produce seeds, they start blooming in no time. Flowering then lasts until the last sunny and warm days of autumn if the plant is well fed.

Leaves are deciduous, almost leathery, oval, bright maroon when they emerge, darker maroon as they mature, and dark green on less insolated parts. In acid soil they gain fantastic fiery red and orange shades in autumn. After they have fallen down older plants reveal flaking-off bark, similar to what plane trees or stewartias do, leaving a mosaic pattern on the smooth trunks. DOUBLE DYNAMITE^® crepe myrtle was granted a US patent No. PP27,085 in 2016.

This is a tree form (standard tree) of crepe myrtle. Plants are either grafted on l. indica rootstock or grown from cuttings of the variety. Remember that the trunk height you see in a nursery will remain unchanged in future, i.e., if you buy a half-standard with a trunk height of one meter it will not grow taller, only thicken. Therefore, if you are looking for a taller trunk in maturity you have to buy a tree with a trunk of the desired height now.

Crepe myrtles need little care. They need full sun with zero shade during the day. Grow them in well-drained soil that should be kept moist before the plant is fully established. If cultivated in acidic soil the plant will make fabulous colour play of autumn foliage. Crape myrtle needs heavy mulching in winter and some mulch in summer to retain moisture. Fertilize it in spring to encourage growth (nitrogen-based fertilizers), and in summer to encourage flowering (phosphorus-based fertilizers). Hardiness of standard trees varies with rootstocks: plants grafted on l. indica withstand -17 °C (USDA zone 7), but trees produced from cuttings or grafted on self are hardy to about -21 °C (USDA zone 6b).

Last update: 08-10-2023