For the purpose of this page, we are
interested only in that group known as Japanese Maples - or Japanese
Acers. These normally fall in the group known as Acer palmatum -
which is to say that the foliage is generally palm-like. (As
in hand rather than palm trees!).
There is another group of the Acers which can rightly claim to be known
as Japanese maples. These are those Acers in the Acer japonicum
group. (japonicum = of Japanese origin).
Most of the shrubs - in either group - have good autumn colour foliage,
and also attractive foliage for growing seasons. All are deciduous.
Foliage colour - Summer and
Autumn - is determined to a great extent by the
growing conditions regarding soil type and also
the weather conditions.
The Acer family of trees - Japanese Maples -and shrubs
is a wide ranging group. In terms of size, they can be anything from
dwarf shrubs of just under a metre height, to largish trees with a
height of 8-10 metres. Either as shrubs or trees, it is the
foliage which is the attraction. Often attractive in the spring and
summer, but it is the colour in the autumn for which they are really
Single leaf of Japanese Maple
- Acer palmatum 'Dissectum' - showing
seven distinct lobes, which are then further
divided to put it into the 'Dissectum' group -
Acer palmatum 'Dissectum'. This is the
early Autumn colour of an otherwise light green
A point that is overlooked with the Acers group
generally, is that there are several types that
have variegated foliage. These though do not
generally have the same Autumn colour effect as
the non-variegated forms.
Spring is also a good time for Japanese Maple
foliage colour. The colour of the purple forms in
particular have a good Spring colour - at bud
break and afterwards before the summer period. It
is at this time of year that the foliage of Maples
can be damaged, by late frosts and drying winds.
the damage persist throughout the year on many.
Summer is also a period where Japanese Maples can
suffer foliage damage from hot, scorching sun.
This is often mistaken for being some type of
disease. Not so - simply sun - or wind scorch - of
the Acer foliage.
General Care of Japanese Maples
Acer japonicum and Acer
palmatum originated in woodlands and forests. This important fact,
gives us clues as to their general likes and dislikes. Because of their
origins, they are happiest in dappled shade, and growing in an organic
type soil which is at the same time well drained. This applies to
whether they are grown in containers or in the open ground. They will
though, survive in most types of soil, but do better in soils of high
organic content. This would have been natural in their native habitat.
Container Growing Japanese Maples.
Japanese Maples are admirable subjects for growing in good sized
patio pots or other containers. A good organic potting compost with
added soil and grit will normally be the best compost to use. The size
of some varieties will be restricted by this method of growing - no
Advantages include the fact that the pot can be placed in
a sheltered situation - avoid draughts from alleyways if on the patio.
The pot can also be re-positioned in a sheltered place for hard winters,
ready to be bought out on display in the spring though to autumn.
Foliage damage of Japanese Maple can result if the containerised
Maple is placed in a position where it is likely to be brushed against.
Damage can also be attributed to placing the container in an exposed.,
Add slow release fertilizer such as Osmocote at planting time, and
then each spring. The shrub should not require any additional feeding
throughout the summer months.
Watering will be required daily through the growing season if dry.
Ensure that the soil does not become waterlogged through over watering
or poor drainage.
Winter root damage can occur if the pot becomes iced-up for long
periods. This can be prevented by 'lagging' the pot for the winter
months, or simply by pacing other pots around in a tight cluster. Most
patio pots - and Acers are no exception - will benefit from having a
huddle of other pots throughout the winter.
Japanese maples often suffer from exposure to hot sunshine, where the
delicate leaves are scorched. The same it true of draughty conditions.
As the foliage of the Japanese Maples are the main attraction, it makes
sense to protect the shrubs form extreme conditions in order to prevent
foliage damage. They are generally slow in growth, so a damaged leaf is
probably visible for the entire growing season - not being hidden by
continues foliar growth. Basically, what you see during the first
two months of growth, is what you get for the remainder of the season.
There can often be a little bit of twig die-back after a hard winter.
It is normally sufficient to simply cut out the dead growth before the
growing season starts.
Foliage Colours and Types.
The Acer palmatum group of Japanese Maples have
a wide range of colours and leaf forms. The colours can range from lime
green, through to the deepest red or maroon bronze. Added to this, there
are the varied leaf forms which add so much interest to these shrubs.
The basic leaf of the palmatum Japanese Maples,
is -as its name suggests - palm-like, with normally five lobes or
fingers, but can be as many as nine distinct leaf lobes. In many
varieties, each leaf lobe can be further finely divided. This group is
known as the Dissectum group of Japanese Maples - Acer palmatum
In Japanese maples with either the basic or dissected
foliage, there are then many varieties which have the wide range of leaf
colours referred to above. There are also variegated leaved varieties.
The common factor is, that they all have good autumn colour. The extent
of the autumn colour can be determined by general growing conditions and
soil types - as well as the preceding growing season.
The 'Dissectum' group of Acer japonicum
are normally dwarfer in growth, and often with a domed
habit. This makes them particularly suited to rock
gardens and the like.
Left is a 'typical' Acer palmatum - showing
the five-lobed individual leaves. Centre and Right
shows the leaves of the 'Dissectum' group - being
Acer palmatum 'Dissectum'. In this group,
the leaves are still primarily five-lobed, but now
each lobe is split into sometimes intricate
Left is the typical Acer palmatum
'Atropurpureum' - just starting its
autumn tints. Then there are images
of a typical
Acer palmatum 'Dissectum Atropurpurea' with
the finely cut foliage.
Problems with Japanese Maples.
Most Japanese maples have no problems for most of the time.
Especially if given the right growing conditions as above. However,
there are a range of pests and diseases that can be problematic. As
usual, the pests are easier to deal with than the diseases.
Pests of Japanese Maples include sucking
insects such as aphids and scale insects. Sometimes
caterpillars and more rarely spider mites. The infestation by aphids
is normally first noticed with a stickiness on the foliage - in advanced
infestation it will have perhaps turned to sooty mould.
Scale insects are a little more difficult to deal with than
aphids. Whatever, there should
be a swift response, for if the foliage is at risk, then so is the
beauty of the plant - not to mention the overall effect on the plant's
Foliage can be damaged by foraging deer. Bark can be chewed by
invading rabbits. Both pests should be dealt with as necessary. It will
need exclusion, or other drastic action.
Diseases of Japanese Maples will include Coral
Spot Disease, which is visible on the bark or - worse - the bare wood of
the branch - normally as orange spots and growths. There is no chemical
control available for this fungal infection. Cut out the affected
growths and burn. It is normally a sign of a general malaise of the
plant, so cultivation care needs to be looked at. One of the suspected
causes is said to be pruning the shrubs in wet weather. This would
include taking off the winter damaged sections in spring. Do this when
the weather is DRY! Dieback and bare branches are usually the first sign
of coral spot disease.
Leaf Tar spot is unsightly -but rarely has any detrimental effect.
Pick off the affected leaves and destroy.
More serious is the disease of Honey Fungus. It normally leads to the
death of the shrub.
Leaf scorch damage and wind damage should have been
prevented. there is nothing you can do to repair the unsightly leaves!
Likewise, late frosts can kill the young emerging leaves. Remove all and
hope to see re-generation of new growths.
Pruning of Japanese Maples.
Japanese Maples should only be pruned if absolutely essential - but
preferably not at all. If you must, then simply take out any dead or
diseased wood - in DRY weather conditions - in the dormant late Autumn
Propagation of Japanese Acers.
Seed propagation is possible with many varieties - if they set seed.
It is best to collect the seed as soon as it is ripe, and sow in the
open ground in similar conditions to the parent plant. Seedling emerge
in the spring with luck (!), and can be carefully transplanted as soon
as they have a few pairs of leaves. Water well a few hours before
attempting to transplant.
Cuttings are difficult - but certainly not impossible.
cuttings can be used. It is normally the aftercare of the rooted
cutting which are the most critical, and also getting them through the
fist winter. (In a cold greenhouse or cold fame preferably).