Why Is My Potted Japanese Maple Not Growing Well?

Filed Under: Trees, Watering · Keywords: Potted, Japanese Maple, Not Growing · 1049 Views
I have a Mikawa yatsubusa JM that I've had two years. It is growing in a large pot. The first year it did fine, I moved it into my garage for the winter and moved it back out on the 2nd day of May and, of course, we had a frost that night. I live in zone 5 Mt. States. It wasn't a hard frost but it did blacken the ends of the leaves. It started new light green leaves bug since then it has not grown at all. It looks just like it did when it started the new leaves. What has happened to it? It has morning shade and afternoon sun, we have had a very hot summer so far, ranging from mid ninety to three digit highs. How much should I be watering, should I move it into total shade while it remains so hot or what do you suggest?


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Answer #2 · John Heider's Answer · Hi Ronda-I just noticed Brooks answered your question also. He is very knowlegable regarding Japanese maples. I'll give you my answer also as it recaps some of what he has already said.

It sounds as if your japanese maple is going throught some shock first from the frost damage and now the unseasonably hot summer. Japanese maples will tend to slow their growth in extreme hot weather.
Although the Mikawa yatsubusa is a fairly hardy variety that takes more heat than others it does need protection from direct sunlight especially when the weather is above the high eighties low nineties. Protection from hot winds is extremely important also.

At this time I would prune off any dead stems and remove any completely damaged leaves. The Japanese Maples have a second set of leaves that will probably start appearing in a couple of weeks. Move the tree into filtered light where it is protected from direct hot sunlight and drying winds. Potted trees will have a tendency to dry out faster in this warm weather. First make sure the trees potting soil is well draining. Soil that holds to much water can be as damaging as too little water. You can dig down 6 to 8 inches and check the soil water content. The soil should feel cool and moist, not dry or wet. Even in the shade I water my potted maples twice a week in this warmer weather. Of course this depends on how well draining your soil is. It is also important to make sure at least once a week your pots are watered well enough to drain freely from the bottom to make sure the soil is moist evenly throughout the pot. I keep a layer of bark over the potted soil to help hold moisture in and keep the soil and surface roots cooler. At this time I would also hold up on any fertilization as forcing a tree that is already stressed could harm it even more. If your tree showes no signs of spotting or discoloration of leaves and stems, swelling areas of stems, or signs of insects I think removing it from hot direct sunlight and monitoring its moisture will help to pull your tree from the stress it is experiencing.

You mentioned you had moved your tree in the garage for the winter. It is wise to protect a potted tree in the winter from freezing winds that can damage the tree and its surface roots. It is also important that your tree gets as much cold weather as possible so that it goes into a completely dormant state to stay healthy and produce nice growth the following year. Your tree is hardy to zone 5 so it should survive the winter in a protected location. The garage could possibly be to warm for a good dormancy. Here in zone 9b many of our Japanese maples tend to deteriate slowly over the years and don't develop each year or have the longevity they should have because of our warmer winters.

Hope this helps. Let me know what happens after it has been protected from the afternoon sunlight and keep moist, not to wet, for awhile.

John)


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Ronda Harrison

Ronda Harrison · Gardenality Sprout · Zone 5B · -15° to -10° F
I will be checking the soil moisture right away as well as the suggested pruning. I will let you know if it begins to respond to all your suggestions. Thanks so much

2 years ago ·
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John Heider

John Heider · Gardenality Genius · Zone 9B · 25° to 30° F
You are very welcome.

2 years ago ·
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Answer #1 · Brooks Wilson's Answer · Hi Rhonda,

I know that extremely high temperatures can cause Japanese Maples to stop growing. Japanese Maples usually put on new growth in the spring. When the temperatures hit the 90's and 100's they tend to go dormant. As cooler temperatures hit in the fall a fall flush of new growth usually occurs.

Mikawa Yatsubusa Japanese maples also prefer morning sun and afternoon shade. You mentioned that your tree is getting afternoon sun. This is not good. Moving it to a morning sun only application or filtered sun may fix your problem.

Have you fertilized the Japanese Maple this season?

I know a lot about Japanese Maples having 65 of them in my home landscape as well as hundreds on a continual basis at my nursery business, however, don't know the effect of moving one inside for the winter. If doing this I would move it outside on nicer days and only move it in when the weather is extremely cold. If the pot is large and hard to move you may want to look in to using a plant caddy with wheels. Then you can roll it in and out. If the temperatures are above freezing definitely have it outside when possible, even if it's only during the daytime hours.

Japanese Maples are drought tolerant and don't like wet feet. It's best to water potted Japanese Maples thoroughly, making sure that when watered the entire root system to the bottom of the pot is wet. Then give the it a break. Only water when needed. During drought times I water my Japanese Maples in pots once or twice a week. If we get regular rain I don't water them at all.

Hope this helps you out.

Brooks Wilson))


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Ronda Harrison

Ronda Harrison · Gardenality Sprout · Zone 5B · -15° to -10° F
This helps me so much, thank you for giving me this advice

2 years ago ·
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