Japanese maples will be healthy all summer and autumn with 1 simple care tip

Japanese maples are a stunning addition to any garden, but they can be tricky to care for in summer.

Japanese maples, also known as Acer, are highly valued for their brilliant foliage, which transforms into a stunning deep crimson when properly maintained.

This tree gives any garden a more dramatic appearance from summer into autumn. However, while many gardeners attempt to nourish their trees during warmer months, doing so at the wrong time can leave Japanese maples under strain and severely compromised.

The issue is that Japanese maples are especially susceptible to heat. Their root systems lie near the surface, rendering them more prone to desiccation and more liable to respond adversely if fertiliser is applied during hot periods.

Numerous all-purpose feeds contain salts and chemicals which can singe roots and leaves when the ground is already warm, and the plant is experiencing stress.

Specialists at Mendocino Maples Nursery state that the final safe period to fertilise a Japanese maple is early May; beyond that, it’s preferable to concentrate on keeping the root zone cool and damp rather than encouraging fresh growth.

Instead, they advise adding one simple natural material to the ground: mulch. They explained: “Mulch is a good friend of your maple. Mulch protects the roots from the heat in summer, the cold in winter and reduces the frequency of watering.”

Why mulch helps Japanese maples in summer

Japanese maples naturally flourish in woodland environments where the earth is blanketed with fallen leaves. That covering functions as a protective layer, helping the soil retain moisture and safeguarding shallow roots from direct sunlight.

Mulching replicates those conditions within UK gardens. A layer of organic material helps the soil retain moisture, reduces temperature fluctuations around the root zone, and diminishes the risk of the tree becoming stressed during prolonged periods of warm weather.

Over time, organic mulch decomposes, enriching the soil and encouraging healthier growth without the need for additional fertiliser.

How to apply mulch to a Japanese maple properly

To mulch effectively, concentrate on protecting the roots while preventing moisture from accumulating against the trunk. Begin by clearing away any weeds, grass or debris from around the base so the mulch can sit directly on the soil.

Next, apply the mulch in a wide ring across the root area, leaving a gap around the trunk so that none of the material comes into contact with the bark, as trapped moisture can cause rot.

A layer approximately 5–8cm deep is generally sufficient to insulate the soil and help it retain water, and it should be watered thoroughly afterwards to help it settle and hydrate the ground beneath.

With the roots insulated and the soil remaining cooler and moister, Japanese maples are considerably more likely to maintain their foliage at its finest through late summer and into autumn — without the risks that feeding during hot weather can pose.

What else should you do?

The technique you use when watering is every bit as crucial as mulching. According to Japanese Maples and Conifers, when watering Japanese maples, it’s advisable to provide them with a thorough watering, which means several minutes with a hose or an extended period with a sprinkler for trees planted in the ground.

Thorough watering encourages roots to penetrate deeper into the soil, which can help render the tree more resistant to drought. For Japanese maples grown in containers, water until it flows from the drainage holes at the base, ensuring the complete root system receives adequate hydration.

The plant specialists added: “The time of day you water can also be important. Watering your Japanese maples early in the morning is ideal.

“This allows the trees to absorb moisture before the heat of the day sets in, reducing the risk of evaporation. Early morning watering also helps prevent fungal diseases, which can thrive in moist conditions during the cooler evening hours.

“When watering Japanese Maples, avoid using overhead sprinklers that wet the leaves if you can help it. Wet foliage can lead to fungal diseases and leaf scorch in the hot sun.

“Instead, use a soaker hose or drip irrigation system that delivers water directly to the root zone, ensuring efficient water use. Japanese maples are only going to drink water from the roots, so there is no benefit from watering the leaves.”