A Detailed Guide to the Latest Methods for Making and Caring for Crape Myrtle Bonsai

Crape myrtle is an excellent bonsai material for viewing flowers, trunks and roots. Also known as Jing'er tree, Hundred-Day Red, Mantang Red, and Ticklish Tree, it is a deciduous shrub or small tree of the genus Lagerstroemia in the family Lythraceae. Its tree form is graceful, its trunk is smooth and clean, and its flower colors are brilliant, giving it extremely high ornamental value. Let us take a look together at how to make and care for crape myrtle bonsai!

Growth Habits of Crape Myrtle

Crape myrtle prefers a warm and humid climate, likes light, is slightly tolerant of shade, likes fertilizer, and especially prefers deep, fertile sandy loam. It thrives in places with slight moisture, is also tolerant of drought, and dislikes waterlogging. It should not be planted in low, damp places with a high water table. It likes warmth by nature and can resist cold. It has strong sprouting ability and a relatively strong resistance to pollution, with fairly strong resistance to sulfur dioxide, hydrogen fluoride and chlorine gas. It is semi-shade growing, likes to grow in fertile and moist soil, and can also tolerate drought. It grows well in both calcareous soil and acidic soil.

Making a Crape Myrtle Bonsai

1. Grafting to change varieties: Crape myrtle has a well-developed root system, and after the roots are cut it extremely easily produces new roots, so it easily survives when potted. After obtaining a fairly ideal crape myrtle stump, you should first cut and prune it according to the needs of the bonsai design. If the stump has a good root system, it can be planted directly in a pot to cultivate relatively thick branches, which helps the graft survive. This is generally habitually done before spring bud break; in fact, different grafting methods can be used, and grafting can be done in all four seasons. Depending on how well the grafts take, multiple supplementary grafts can be made.

2. Digging from the wild: The digging time for crape myrtle is generally from early October to before bud break in early spring, and the cold season and dry-wind weather should be avoided as much as possible. When digging, first select old stumps with thick, strong rhizomes, gnarled and unusual forms, or trunks that have been hollowed out by erosion, resembling wrinkled, perforated, leaky grotesque rocks. After digging them up, plant them directly in pots, or plant them in moist, fertile, loose and breathable soil for cultivation. Once the root system has resumed growth and the branches and leaves are luxuriant, move them into pots.

3. Potting and planting: When potting a crape myrtle bonsai, arrange the stump specimen well according to the shape of the crape myrtle bonsai stump and the future styling needs. Then pour the prepared loose, fertile humus loam into the pot all around, so that the root system and soil are firm and dense, water thoroughly to settle the roots, and place it in a wind-sheltered, shaded place for care. Normally, water should be sprayed frequently on the branches and trunk to keep them moist and prevent the trunk from drying out in the wind. After budding, move it to a sunny place for normal care.

Caring for a Crape Myrtle Bonsai

1. Reasonable watering: In the early stage of branch and leaf growth, the amount of watering should be properly controlled to restrain the growth of the branches and leaves of the crape myrtle bonsai. In this way the branches are thick and strong and the leaves are small, avoiding large leaves and sparse nodes, which would seriously affect control of the tree shape. From budding to the flowering period, watering should be sufficient. In the high-temperature and drought season of summer, the amount of watering should be increased, and water should often be sprayed on the leaf surfaces of the canopy to increase air humidity. In winter, reduce the amount of watering, and keep the potting soil slightly dry.

2. Timely fertilizing: Crape myrtle bonsai is mainly given sufficient base fertilizer in winter. During the growing season, about once a week, apply a cake liquid fertilizer and other phosphate- and potassium-free chemical fertilizers. Before and after budding, a 0.2% potassium dihydrogen phosphate solution can be used for foliar spraying to promote flower bud differentiation and flower bud enlargement. After each flowering, sufficient base fertilizer must be applied. Especially for crape myrtle bonsai that have already taken shape, when they flower 2 to 3 times in the same year, it is particularly important to apply sufficient base fertilizer in combination with pruning and shaping; otherwise there will be branches but no flowers, or the flowers will be sparse and the flower color will not be brilliant, failing to achieve the best ornamental effect.

3. Repotting and changing soil: For crape myrtle bonsai, this should be determined according to its growth vigor. Repot and change the soil once every 2 to 3 years, and this can be done in either winter or spring. According to the needs of the crape myrtle's tree form, replace the pot in good time. Remove all or part of the old soil. After the stump is taken out of the pot, remove the surrounding soil and some decayed roots, thick roots, long roots and overly dense roots, place the plant into the pot, add the growing medium and press it firm, and water thoroughly. The growing medium must be rich in organic matter, have good drainage and air permeability, and be sufficiently fertile, so as to ensure it has abundant flowers and luxuriant leaves.

4. Shaping and pruning: For the shaping and pruning of crape myrtle bonsai, after leaf fall, according to the needs of the bonsai styling, ordinary branches should be heavily pruned by leaving 1 to 2 buds on each branch. Pruning during the growing season mainly removes overly dense branches, water sprouts that disrupt the tree shape, and branches sprouting from the base trunk that have no useful value; all of these should be removed or cut off in good time.

5. Removing spent flowers: To make crape myrtle bonsai bloom multiple times and bloom well within one year, after each flowering, remove the spent flowers in good time to prevent fruiting and to promote the rapid enlargement of secondary flower buds, resulting in multiple blooms. However, the flowering periods come one after another and are not neat enough. In addition, after the flowers fade, if there are not many secondary flower buds, leave 1 to 2 buds on each branch and prune heavily. Buds generally appear in 14 days, and in about 35 days the whole tree can be full of flowers. In this way the branches of the crape myrtle bonsai can be made even thicker and shorter (average branch length within 15 cm), the tree shape very compact, and the flowers abundant and brightly colored, pleasing to the eye.

Pest and Disease Control of Crape Myrtle

1. Powdery mildew

[Symptoms] Powdery mildew mainly harms leaves, and young leaves are more easily infected than old leaves. The disease also harms branches, young shoots, flower buds and flower buds. In the early stage of the disease, small white powdery spots appear on the leaves, and after they expand they become round or irregular discolored patches. After flowers are infected, their surfaces are covered with a white powdery layer, and the flower spikes become deformed and lose their ornamental value. Plants attacked by powdery mildew become stunted, with young leaves twisted, deformed and withered, leaves not expanding and becoming smaller, and branches deformed; in severe cases the entire plant dies.

[Control] (1) Strengthen fertilizing and pay attention to drainage to avoid excessive humidity. Reduce sources of infection: in combination with autumn and winter pruning, remove diseased and dead branches and burn them in a concentrated manner; during the growing season, promptly remove diseased buds, diseased leaves and diseased shoots. When plants develop the disease, spray 25% triadimefon wettable powder at 3000 times dilution, or 70% thiophanate-methyl wettable powder at 1000 times dilution, or 80% zineb wettable powder at 500 times dilution. Alternating several of these agents gives a better effect.

2. Brown spot disease

[Symptoms] Crape myrtle brown spot disease mainly harms leaves. The lesions on the leaves are round or nearly round, occasionally irregular, purplish brown to grayish brown, with a lighter and indistinct edge color, and grayish black small mold spots on both sides. After several lesions appear on the leaf surface, the whole leaf quickly turns yellow and falls early. High temperatures, high humidity and frequent rainfall favor the occurrence of this disease.

[Control] Carry out autumn plowing of crape myrtle gardens or street crape myrtles, turning the surface fallen leaves into the deeper soil to reduce the primary infection source for the following year. Prune in good time to allow ventilation and light penetration. In the early stage of the disease, promptly spray 50% benomyl wettable powder at 1000 times dilution, or 75% chlorothalonil wettable powder at 800 times dilution.

3. Crape myrtle aphid

[Symptoms] The crape myrtle aphid causes damage to crape myrtle every year. The undersides of young leaves are often covered with the pests; after damage, new shoots are twisted, young leaves curl and become uneven, affecting flower bud formation and shortening the inflorescences, or even resulting in no flowers. At the same time, it also induces sooty mold and spreads viral diseases.

[Control] In winter, in combination with pruning, remove diseased and pest-infested branches, weak and thin branches, and overly dense branches, which can help kill some overwintering eggs. For household potted plants, the branches and trunk should also be kept as clean as possible; pay attention to removing the split bark layers at the branch forks and burn them in a concentrated manner to reduce overwintering aphid eggs. For chemical control, spray 10% imidacloprid wettable powder at 1500 times dilution, or 50% fenitrothion emulsifiable concentrate at 1000 times dilution, 40% omethoate emulsifiable concentrate at 1000 times dilution, and 80% dichlorvos emulsifiable concentrate at 1000 times dilution, etc. At the same time, this can also control pests such as crape myrtle felt scale.

4. Felt scale

[Symptoms] The felt scale damages plants by female adults and nymphs sucking sap at bud axils, leaves and branches. It often causes weakened tree vigor and poor growth, and the large amount of honeydew it secretes induces severe sooty mold, causing leaves and small branches to turn black and lose their ornamental value. It is one of the main pests harming crape myrtle.

[Control] Strengthen quarantine to prevent the introduction of the pathogen; fertilize reasonably to enhance the plant's insect resistance; maintain ventilation and light penetration, and avoid overly dense planting; in combination with winter and early spring pruning, burn infested branches in a concentrated manner. When the pest population is small, it can be removed manually by scraping. In winter, spray 10-15 times diluted rosin mixture or 40-50 times diluted machine oil emulsion 1 to 3 times to kill overwintering female adults. Before bud break, spray 3-5 degree lime sulfur mixture or 3-5% diesel emulsion to kill overwintering nymphs.

5. Sawfly

[Symptoms] Sawflies damage plants in groups as larvae, feeding on leaves and gnawing the leaf mesophyll, eating the young leaves of the plant completely and leaving only a few main veins. This affects the plant's photosynthesis, affects the flowering period of crape myrtle, reduces its ornamental value, and may even lead to death.

[Control] In winter and spring, in combination with soil plowing, eliminate overwintering cocoons. Look for egg-laying shoot tips and leaves, and manually remove egg-bearing shoot tips, egg-bearing leaves, or larvae that are still clustered after hatching. During the larval damage period, spray Bt. emulsion at 500 times dilution, 2.5% deltamethrin emulsifiable concentrate at 3000 times dilution, 20% fenvalerate at 2000 times dilution, or 25% chlorbenzuron No. 3 suspension concentrate at 1500 times dilution.

6. Yellow slug moth

[Symptoms] The yellow slug moth mainly causes damage by larvae gnawing.

[Control] Physical control mainly involves winter pruning in combination with removing overwintering cocoons on branches, thereby eliminating or reducing the pest source. For chemical control, it is best to apply the pesticide before the larvae spread. Spray 80% dichlorvos emulsifiable concentrate at 1000 times dilution, or 2.5% deltamethrin emulsifiable concentrate at 2000 times dilution.