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Japanese maples

Acer japonicum 'Acontifolium' (courtesy Horticopia)
The diverse beauty of Japanese maples has captivated gardeners for centuries. During the Edo era in Japan, over 250 named cultivars were selected and grown. Today, there are over 1,000 varieties of different sizes, shapes and hardiness levels.

Japanese maples are especially prized for the diversity of size, shape and colour of foliage. Foliage colour changes with the season, and many are especially spectacular in the autumn. Japanese maples are usually categorized according to leaf type. These include: palmate types: large leaves that look like your hand. Deeply divided types: the leaves are divided down to the petiole. Dissected leaf types: the leaves are fine and deeply dissected or serrated. Other: these include variegated leaf types and linear lobum or line-leaf types.

Planting and care of Japanese maples

Site selection:
Japanese maples grow well in our climate if a few basic principles are followed. The most important is to select a sheltered planting site that is out of the severest northwest winter winds. If it must be exposed to wind, ensure the tree is well wrapped with burlap in the winter months. Japanese maples grow well in any well-drained soil. They grow in full sun to almost full shade and will do best with protection from mid-day sun. The amount of light will affect the leaf colour; red leaf types will be more colourful in higher light conditions.

(Courtesy Horticopia)

Lacy-leaved Japanese maple cultivars add a fine texture to the landscape.
Photo by Susan Preston

Planting:
Mix one part peat moss to three parts of soil in the planting hole, which should be much larger than the root ball. Water heavily at time of planting and mulch the entire area with a two-inch layer of bark or leaves to ensure water retention and keep the roots cool. Only moderate amounts of fertilizer such as a transplanter with a formula in ratio of 5-15-5 should be used at planting time.

Fertilizing and trimming of established plants:
Once established, Japanese maples may be lightly fertilized only in the early spring (April) with 4-12-8 fertilizer or 15-30-15 water soluble mixture. Major structural trimming may be done before the new leaves unfurl in spring. Lighter pruning can be accomplished any time in June after the first major flush of growth begins.

Diseases:
Japanese maples are subject to very few pests. Aphids, leaf cutters and rollers may appear in the spring and can be effectively treated with an approved spray. (Ask the experts at your local garden centre to recommend an appropriate product). Mildew may appear in humid conditions.

Winter protection:
Wrap Japanese maples with burlap for at least the first three years in the garden. In more exposed locations, wrap every year. A heavy watering just prior to freeze-up will help to guard against water loss in winter. An extra heavy layer of mulch will also help to protect the root system.

Japanese maple varieties:
The diversity and popularity of Japanese maples make it virtually impossible to predict their availability in any given year. Consult with your local garden centre staff for the cultivars currently available. Following is a brief list of some of the more commonly stocked Japanese maples.

Common name
Botanical name
HeightZoneDescription
Golden full moon maple
Acer japonicum 'Aureum'
3m tallzone 6Rounded yellow leaves add a bright contrast to the garden.
Slow growing; prefers a sheltered site.
Fern leaf maple
Acer japonicum 'Aconitifolium'
5m tallzone 5 Broad, deeply cut green leaves turn a brilliant scarlet in the fall. Upright, multi-branched habit.
Golden Japanese maple
Acer palmatum 'Aureum'
5m tallzone 5 Yellow leaves with distinctive light green undertones.
Bright yellow fall colour.
Bloodgood Japanese maple
Acer palmatum 'Bloodgood'
6m tallzone 5 One of the most popular and hardy varieties.
Deep, purple-red leaves hold their colour well all season.
Emperor 1 Japanese maple
Acer palmatum 'Emperor 1'
6m tallzone 5 Extremely dark purple foliage fades little in summer heat.
Hardy and vigorous.
Fireglow Japanese maple
Acer palmatum 'Fireglow'
5m tallzone 6 Bright, reddish-purple foliage allows this tree to stand out in any landscape.
Osakazuki Japanese maple
Acer palmatum 'Osakazuki'
6m tallzone 6 Large green leaves in summer turn brilliant scarlet in fall.
Red Pygmy Japanese maple
Acer palmatum 'Red Pygmy'
1.5m tallzone 6 Dwarf variety with deeply cut, very narrow lobed red leaves turning orange-yellow in the fall.
Suminagashi Japanese maple
Acer palmatum 'Suminagashi'
4m tallzone 5 Serrated, deeply divided wine-red leaves on a hardy tree. Very attractive.
Crimson Queen cutleaf maple
Acer pal. dis. 'Crimson Queen'
2m tallzone 6 Deeply divided red cutleaf maple turning scarlet in the fall. Graceful, mounding habit.
Green cutleaf maple
Acer pal. dis. 'Viridis'
1.5mzone 6 Finely dissected lacy green leaves turn golden yellow in the fall. Beautiful weeping form.
Inaba Shidare cutleaf maple
Acer pal. dis. 'Inaba Shidare'
2m tallzone 6 Vigorous grower with deep purple-red deeply cut leaves turning bright scarlet in fall.


Japanese Maples

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