Red Sunset red maple

Sun

Full sun for the strongest autumn colour; tolerates partial shade.

Water

Moderate to high; keep young trees evenly moist and water established trees during prolonged dry weather.

Soil

Moist, acidic soil, preferably loam; tolerates clay and occasional flooding. Alkaline soil commonly causes yellow leaves, and dry, compacted ground limits growth.

Height

40-50 ft (12-15 m)

Spread

30-40 ft (9-12 m)

Flowers

Small red flowers on bare branches in late winter or early spring, before the leaves open.

Foliage

Deciduous green leaves with three to five pointed lobes and pale undersides; usually orange-red to deep red in autumn, with colour affected by weather and soil.

Growth

Moderate to fast, often 1-2 ft (0.3-0.6 m) a year while young in suitable conditions.

Care needed

Medium

• Pollinators
• Cold hardy
• Heat tolerant
• Wildlife

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   7 ft (2 m)

2. After 1 year

   9 ft (2.7 m)

3. After 2 years

   11 ft (3.4 m)

4. After 3 years

   14 ft (4.2 m)

5. After 5 years

   18 ft (5.6 m)

About 16 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Native to

the US and Canada

Growth rate

Fast

• Plant with the root flare visible at soil level; loosen or correct circling roots before backfilling.
• Water deeply through the root ball and surrounding soil during dry spells for the first two to three growing seasons.
• Spread mulch 2-3 in (5-8 cm) deep over the root zone, keeping it clear of the trunk.
• Allow generous clearance from paving, drains and buildings; shallow roots can lift hard surfaces.
• Feed only if a soil test or poor growth indicates a deficiency; avoid heavy lawn fertiliser applications over the roots.
• Stake only if the root ball is unstable, and remove supports after the first growing season.

Pruning. Train young trees to one main leader and remove competing leaders or poorly attached branches while they are small. Do routine pruning in summer after the leaves have hardened; remove dead or dangerous branches whenever necessary and never top the tree.

Spring

Plant container-grown trees while the soil is workable, keeping the root flare above the finished soil level.

Spring

Renew mulch and check that ties are not rubbing or constricting the trunk.

Early summer

Check new leaves for yellowing between green veins; test soil pH before treating suspected iron deficiency.

Summer

Water deeply during dry spells and carry out light formative pruning if needed.

Autumn

Plant while the soil remains warm and moist; water newly planted trees if rainfall is insufficient.

Winter

Inspect the bare crown for damaged branches and weak forks, and arrange professional assessment of large defects.

• Use as a specimen in a large lawn where its autumn crown can be seen from the house.
• Plant as a shade tree away from patios and paths to reduce future root conflicts.
• Place at a woodland edge with moisture-loving shrubs and groundcover.
• Use in a spacious rain garden or low-lying lawn that drains between periods of flooding.

Garden styles it suits: Autumn colour, Woodland, Traditional, Grand estate, New England and Wildlife garden.

Plant it with: Virginia sweetspire, Summersweet, Oakleaf hydrangea, Christmas fern, Foamflower and Pennsylvania sedge.

Wildlife: Early flowers provide pollen and nectar for insects, and red maple supports moth and butterfly larvae. Winged seeds are eaten by birds and small mammals, while mature branches provide shelter and nesting sites.

• Iron or manganese chlorosis: leaves turn yellow between green veins, especially in alkaline soil. Test the soil and seek a targeted treatment; persistently alkaline sites are better planted with a more tolerant tree.
• Drought stress and leaf scorch: brown leaf margins and early leaf drop follow dry conditions. Water deeply, mulch broadly and reduce competition from turf.
• Girdling roots: circling roots can constrict the trunk and cause gradual decline. Inspect the root flare and have an arborist assess established girdling roots.
• Verticillium wilt: sudden wilting or branch dieback may affect part of the crown. Obtain a diagnosis, remove dead wood and maintain even moisture; there is no curative treatment.

Red maple leaves, especially wilted or dried leaves, are highly toxic to horses and can cause life-threatening destruction of red blood cells. Keep trees, fallen leaves and prunings away from horse paddocks and hay. It is not known to be toxic to cats, dogs or people, but it is not an edible garden plant.

• Autumn Blaze Freeman maple (Acer × freemanii 'Jeffersred')

  Usually has more deeply cut, five-lobed leaves with stronger silver maple influence. Autumn colour alone is not a reliable distinction; check the nursery label.

• Sugar maple (Acer saccharum)

  Leaves usually have five lobes with rounded, U-shaped spaces between them and relatively few coarse teeth; red maple has sharper, V-shaped spaces and more finely toothed edges.

• Silver maple (Acer saccharinum)

  Leaves are cut much more deeply into narrow lobes and have conspicuously silvery undersides; autumn colour is usually yellow rather than strong red.

The Latin rubrum means red, referring to the tree's red flowers, buds and other seasonal features, while Red Sunset describes the cultivar's autumn colour.

Propagation. Propagate true to cultivar by grafting, budding or professionally managed softwood cuttings. Seedlings will not reliably retain Red Sunset's growth habit or autumn colour.

Accepted botanical name

Acer rubrum

In the US and Canada

Native in Canada and the lower 48 states.

Native range

Alabama, Arkansas, Delaware, Florida, Georgia, Illinois, Indiana, Kentucky, Maryland, Minnesota, New Jersey and New Mexico.

Measured

Soil pH 4.7 to 7.3. Average height 1500 cm.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.