Should a Japanese maple be grown in shade?
Japanese maples and conifers
Should a Japanese maple be grown in shade requires a very short answer – no. There are a number of reasons why it’s not advisable to shade them; first and foremost it’s unnatural. Most people think of a Japanese maple as being a shade tree but in reality the only trees that are shading a Japanese maple are other Japanese maples.
Japanese maples along the Tomoe river
In the wild, Acer palmatum will get up to sixty feet and in cultivation they will reach, in time, a similar size also. The illustrations on this page are of Japanese maples growing along the upper Tomoe river by the Taigetsu Bridge in Aichi Prefecture in Japan. There is a distinct delineation between the maples and the conifers along the river bank – the former are growing where they can get the maximum amount of sun. And these are not small trees either; the people in the photos provide a sense of perspective.
Japnese maples growing by the upper Tomoe river
Path to Kohjakuji temple
The path from the river to the Kohjakuji temple threads through more maples and gives a better idea of how large these trees really are, whilst the first picture shows the nearby Mount Iimori – the maples are growing amongst the conifers and not underneath.
The other reason Japanese maples should not be shaded is because of the need for sun to fully develop the leaf colour. When grown in shade, or even dappled shade, what should last several months or be particularly intense, will fade very quickly or not develop the full depth of colour that a particular cultivar is renowned for.
The argument that Japanese maples burn in full sun is nonsense and has nothing to do with the intensity of the sun but rather the quality of the root system. Commercial nurseries in New South Wales; Australia, the North Island of New Zealand and South Africa all grow Japanese maples out of doors with no shade cover without any ill effects – it would not make financial sense to grow them this way if they were continually getting scorched. In mainland USA the only place where Japanese maples are likely to encounter problems is southern Florida and that’s down to problems in the winter rather than what happens in summer.
If your garden only has space with dappled shade or sun part of the day, they are still going to grow but they are going to be slower plants with less developed colour compared to a maple grown in full sun. The key, as I mentioned earlier, is the quality of the root system – easily achievable with plants in the ground but slightly more problematic with plants in containers.
Container growing in a hot summer climate can present something of a challenge if we’re looking for perfection but there are a number of techniques that can be utilized and I shall be looking at the options in detail in future posts.
The illustrations on this page have been reproduced courtesy of Hajime Hayashida
Popularity: 5% [?]
Excellent article. Since I’m in southern California, I’m looking forward to your posting of container growing in hot climate.
marc
I am about to plant a Standard Acer Palmatum Disectum, pot grown until now,
it will be next to separate planting areas for green Bamboo and French Lavender … the contrast looks superb !near to my Koi pond.
It will receive Sun from Sunrise until 4pm then shade,
virtually frost free, and max Summer temperature around 75F
I intend to plant in a planting area of my natural Indian Stone patio area.
the planting area is approximately 2 feet square and 2 feet deep.
I intend to cover the compost surface with landscape fabric and a covering of 10mm pure white gravel which contrasts with the dark blue/grey of the Indian Stone
any tips please as to:
which compost ?
any tips for drainage ?
Are Japanese Maple leaves safe for Koi ?i.e. non toxic … Koi will chew on anything !
( all leaves are removed by the surface skimmer and bottom drains to avoid ammonia from decaying matter. )
any tips for water retention ? should I mix in some water retention gel crystals as used in hanging baskets ?
should I mix in bone meal to feed the root system ? or any other fertilizer ?
As you’ve raised a number of points that might be of interest to other readers, I’ll answer them in a post in the next few days and if you can provide some before and after photos, that would be much appreciated.
I’ve just put up a post that hopefully answers your questions here.
I tend to agree with you for your climate and similar, except that some variegated cultivars may need protection from the afternoon sun.
On the other hand in hot and dry climates like Southern France, even many green and red cultivars will display characteristic sunburn towards the end of July for maples in full sun grown in the ground, with good drainage appropriate watering and mulching. I think that dryness could be a determinant factor since same maples in similar conditions grown west from here, near the coast, show much less sun damage.
Gomero
From my experience with variegated cultivars, and in conversations with commercial growers in Australia, New Zealand and USA using open ground production, generally they will tolerate full sun with no ill effect. With their reduction in chlorophyll due to the variegation, their need for as much sun as possible compared to plain leaved forms is probably greater.
As far as humidity is concerned, this can make a crucial difference between success and failure (or at least burnt leaves) in a hot climate. With the highest temperatures in Japan coinciding with the highest rainfall, humidity is assured but with dry air, transpiration losses are going to be such that a less than perfect root system is not going to be able to cope. I notice you mention appropriate watering and mulching together – with an effective mulch in place watering should not be necessary and would serve only to confuse the root system by artificially manipulating the water table. Allowing the roots to find a natural water source under the mulch over the course of a season should help to mitigate any damage as constant lack of irrigated water tends to produce a reduction in growth rather than burnt leaves.
Do you find the same problem with dwarf and dissectum forms? Logic would dictate that with a dense canopy of leaves, these types would provide greater shading of the soil and probably a more beneficial micro-climate.
“with an effective mulch in place watering should not be necessary”
Not when you do not get any rain for more than two months as has happened here this summer, if they are not watered they would die. These maples like a short (15′) sprinkling from a drip irrigation system each day to keep the mulch humid. Underneath, the clay is dry to the bone (my water table is 25 meters deep). Do not forget that in their natural range, as you say, they never lack water for long periods. The Mediterranean climate is clearly not very good for Japanese maples.
With an appropriate mulch for a dry climate in place, no rain for two months won’t have any damaging effect. Quite by chance, I grew some seedlings for two and a half years without any natural or man-made irrigation and they happily survived. Although maples never lack rain in the wild, it is constancy rather than quantity that is essential when growing them outside their natural habitat.
You provide a clue in your description of your irrigation method. I assume you are using a conventional mulch such as bark chippings or compost – this is behaving as a sponge and obviously no water is going to penetrate into the soil with the result that most of the feeding roots are going to be in the mulch. The depth of the water table is largely immaterial as there is always going to be moisture in the soil, albeit in quantities we can’t measure by sight or feel, and your maples are able to utilise that when they’re trained to do so.
The inter-related subjects of mulching and watering are of some importance, particularly when grown on the margins of their ‘comfort zone’ such as your Mediterranean climate and I will be covering them in more detail shortly.
I planted a Japanese maple in a sheltered spot in the garden, it survived last winters freezing cold weather. It is in the shade of 2 other small trees, but can’t remember the names of the trees, but one well known the other less so.
The maples leaves do get a bit crispy during the summer, even in the shaded position, anything to help prevent that?
When I had it in the full sun the leaves were even worse!
Also, is there a difference between acer and maple?
PS – not read full article yet!!!