What causes Japanese maple tree leaves to turn brown? Veronica Allen of Huntington Beach wrote our Garden Clinic about a Japanese maple, about 10 years old, whose leaves turn brown on the edges in July or August.
"I've tried different watering regimens," Allen wrote, adding that last summer she tried not watering the tree in the summer, a move that seemed to work. "It kept its green leaves into September," she said. But then this year the leaves started browning in June.
For some answers, we turned to Allan Uchida of Bellefontaine Nursery in Pasadena.
Japanese maples can get brown leaves, especially in hot Southern California. Salts in the soil; dry, windy conditions; and watering methods all play a factor in the amount of leaf damage that you might see. Even fertilizers, poor drainage and small insects can scar the sensitive leaves of this precious tree.
Protection from hot sun can help. Some gardeners have luck with a deep watering to leach salts out of the soil. Thick mulch may help too. But otherwise it's best to simply appreciate the showy colors in the spring and early summer.
A tip: Strip off the damaged leaves and let new growth emerge on smaller trees.
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