Acer (Maple) characteristics and culture.
There are approximately 200 species in this genus
They are deciduous shrubs to trees, cultivated commonly for their attractive foliage (particularly autumn colour). Some taller species provide timber & maple syrup.
Leaves are normally palmately lobed, sometimes entire or compound; opposite, and the autumn foliage is normally very attractive. The bark may also be attractive, with colour or markings on many species.
Insignificant flowers in clusters.
Most maples need cool, moist, well drained soils for best results. They have a spreading, often shallow, root system and small species are unlikely to cause any major problems. Some species will tolerate extreme cold and dryness, but few if any tolerate hot humid climates.
Mulch and feed annually. Well rotted organic fertilisers or manures can be applied in early spring. Irrigate during dry periods, particularly during drought times. If possible provide protection from strong winds. Light pruning might be undertaken to shape a plant or remove dead wood; however, regular pruning is generally not needed, and may detract the from the natural shape of the plant.
Leaves dropped in autumn makes excellent compost. Acer psuedoplatanus has become an environmental weed in some areas (e.g. cool, protected sites in Victoria's Dandenong Ranges), competing vigorously with native trees (eg. Eucalypts & wattles).
Usually propagated by seeds, although the seed are generally only viable for a few months so it is necessary to sow them early, either freshly harvested or after a moist stratification for 2-3 months and then sown. Seeds may be stored in moist sand for some months. Budding/grafting of selected varieties/cultivars is commonly carried out onto seedling rootstock.
Diseases are not commonly serious but can include anthracnose, leaf spots, powdery mildew, wilt and bleeding canker. Hygiene, good ventilation and drainage will usually minimize problems.
Pests are rarely serious but may include mites, thrip and borers.
Acer buergeriunum (Trident Maple) – fast growing, to 5m, young tips copper colour, bright red autumn foliage
A. grosseri –to 6m tall, hardy shrub-like tree from China, attractive white markings on bark, prefers cooler areas, rich red autumn foliage
A. palmatum (Japanese maple) ‑normally 3‑10m, occasionally taller. Essential to avoid hot, dry conditions. There are many different cultivars including some of the best shrubs or trees available for small gardens in temperate climates.
A. palmatum varieties include:
A. palmatum ‘Aureum’ –to 3m tall, fine foliage, yellow to orange autumn colour
A. palmatum ‘Dissectum’ –fine, dissected leaves, lobes of the leaf are each one-serrated. Shape of the plant can be variable, but is commonly more bush-like, getting no taller than 2m.
A. palmatum ‘Dissectum Atropurpureum’ – can get to 4m tall, but may be shorter. Very fine foliage with reddish colourings all year, becoming deeper claret red colour in autumn.
A. palmatum ‘Linearilobium’ - lobes of the leaf are not serrated, giving a different foliage effect. To 2m tall.
A. tegmentosum (Manchurian Maple) – Fast growing hardy, frost resistant to 6m tall, tolerates light shade, bright orange red autumn foliage.
Other commonly grown Acers include: A. rubrum, A. saccharum and A. platanoides, but these are taller and better suited to large gardens or parks.