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For the first two years after planting, soak the root zone slowly once or twice a week during dry weather. The aim is to wet the soil to a foot (30 cm) deep each time. Frequent light sprinklings train roots to stay at the surface, which is exactly the wrong root system for a plant you want to be drought-tolerant.
After establishment, an in-ground crape myrtle needs watering only in prolonged drought. It is one of the more drought-tolerant flowering trees you can grow, and it will show you when it is genuinely short of water: leaves go dull, curl slightly at the edges and the plant sheds some of its interior foliage.
The exception is late spring to early summer, while the plant is extending the shoots that will carry the flower panicles. Drought stress in that window means shorter shoots and smaller flower heads, and no amount of watering later in the season makes up for it. If you water once all year, water then.
Plants in containers are a different case entirely. They dry out fast in summer heat and may need water daily. Check by pushing a finger two inches (5 cm) into the mix rather than by watering on a schedule, and never leave a pot standing in a saucer of water.
Feed lightly, or not at all
This plant flowers well in ordinary soil. Over-feeding, particularly with nitrogen, is one of the most common reasons a healthy-looking crape myrtle carries almost no flowers: it puts all its energy into leaves and soft shoots instead. That same soft growth is also what powdery mildew colonises first.
The most frequent source of excess nitrogen is not deliberate feeding at all, but lawn fertilizer applied over the plant's root zone. The roots extend well beyond the canopy, so a plant standing in a fed lawn is being fertilized whether you meant it or not. If yours sits in lawn and grows strongly but flowers poorly, that is your answer.
Where a feed is genuinely warranted, apply a balanced slow-release fertilizer once in early spring as growth begins, spread evenly over the root area and watered in. Do not feed after midsummer.
| Situation | Feeding | Notes |
|---|---|---|
| Newly planted, first season | None | Let the root system establish; nitrogen now causes top growth roots cannot support |
| Established in a bed, growing well | None, or a light balanced feed in early spring | Mulch renewed annually usually supplies enough |
| Established in fed lawn, poor flowering | None; keep lawn feed off the root zone | Excess nitrogen is the most likely cause of the poor bloom |
| Pale leaves, weak growth, thin shoots | Balanced slow-release feed in early spring | Check drainage and root health first; hunger is rarely the real cause |
| Container-grown | Light balanced feed in spring and again in early summer | Frequent watering leaches nutrients from a pot |
Suckers, and keeping the trunks clean
Crape myrtle produces shoots from the base readily, especially after any stress. Left alone they turn a clean multi-trunk plant into a thicket within two or three seasons, they compete for water and nutrients, and they hide the bark that is half the reason to grow the plant.
Deal with them while they are soft. A shoot rubbed off with a thumb in early summer is gone; the same shoot cut with pruners in winter leaves a stub that produces three more. Walk past the plant every few weeks through the growing season and remove them by hand.
The same applies to small shoots appearing on the lower trunks. Rub them off as they emerge and the lower trunk stays clean and displays its bark without you ever needing to make a pruning cut there.
- Rub off soft basal shoots on sight In late spring and early summer, snap or rub off any shoot under six inches (15 cm) tall coming from the base or the lower trunk. No tool needed, and no wound left behind.
- Cut woody suckers below ground level For anything that has hardened, scrape the soil back and cut it flush at the point it leaves the root or trunk. Cutting at soil level leaves a stub that sprouts a cluster next season.
- Do not use string trimmers near the trunks Bark damage at the base is a major cause of sucker flushes and gives borers and rot an entry point. Keep a mulched, plant-free circle around the trunks so no trimmer ever needs to go there.
Bark, seasons and the plant's odd habits
In midsummer the outer bark loosens and peels away in thin strips, showing smooth cinnamon, tan and pale gray underneath. Do not pull it off before it is ready and do not scrub the trunks to tidy them. It sheds when it is due, and the exposed surface hardens into the color over the following weeks.
This plant leafs out remarkably late. It is often among the last woody plants in the garden to show any green, sometimes weeks after everything around it, and a bare crape myrtle in late spring alarms people every year. Before assuming it is dead, scratch a thin sliver of bark from a young shoot with a thumbnail: green underneath means the wood is alive and you simply have to wait.
In colder areas the top growth may die back partly or completely over winter. Because the plant flowers on new wood, it resprouts from the base and still flowers the same summer, on a shorter plant. Cut the dead wood back to live tissue once you can see where growth is starting, and not before.
Two things are worth recording each year: the date green first appeared on the shoots, and the date the bark started shedding. The leaf-out date in particular saves the same worry every spring, and after two seasons of records the bare plant in late spring stops being a concern at all.
Do not stake an established plant permanently or wrap the trunks. The trunks thicken in response to moving in the wind, and a plant supported for years never develops the strength to hold its own flower load.