Red maple or Acer rubrum belongs to a genus of plants from the Sapindaceae family. It is indigenous to North America, particularly the east and central areas of the continent. It can grow in swamps, in dry soil, almost anywhere except in extremely hot or cold locations.
It can thrive at sea level to altitudes of 3,000 feet and ranges about 1,600 miles from the north, where the temperature minimum means is −40 °F, to the south. Westward, its range ends at the dry weather of the Great Plains. It is frequently grown as shade trees in parks and landscapes due to its gorgeous foliage in autumn. It was introduced in England in 1656 and is frequently found in parks and gardens.
This tree is considered to be vital in forest regeneration of frequently logged forests, although it is less prevalent in old northern hardwood forests. It has a maximum lifespan of 150 years, but generally, most of these trees don’t live more than 100 years.
It is a fast grower – seedlings can grow 0.98 feet at first and then 2 feet every year until reaching maturity. Depending on local growing conditions, it can attain heights of 100-135 feet, with a trunk diameter ranging from 18-60 inches. The lower trunks of trees growing in forests are usually clear of branches, while wider-spaced trees have more rounded crowns, thicker growth, and are not as tall. The bark on younger trees is pale grey and smooth, becoming darker as it matures.
Varying shades of red prevail among the foliage, flowers, and fruit. The 3-5 lobed leaves with jagged edges are about 2–4 inches wide and long. The top of the leaves is light green and white and hairy underneath with red stalks.
The leaves usually become red in autumn, but can also be orange or yellow. Soil acidity also influences the foliage colors. The autumn leaf colors of deep scarlet are more outstanding in northern areas where climates are much cooler.
This tree usually begins producing red flowers after 8 years, but this varies as some trees might start flowering in 4 years. The flowers appear in December until May depending on latitude and elevation, generally before the leaves appear.
Trees growing in locations with poor soil are often scraggly and stunted. The largest living specimen of red maple is 125 feet tall and has a trunk of about 16 feet in width near Armada, Michigan.
The winged fruit is 5⁄8 – 1 inch long, growing in pairs on long slim stems, with a divergent angle of 50-60 degrees. The fruit ripens in April to early June, before foliar growth is complete and the seeds are then dispersed in a period of 1 to 2 weeks from April and July.
These trees can tolerate flooding, one study documenting that no leaf damage occurred despite being flooded for 60 days. They are also tolerant of drought as they can stop growing in dry conditions and then later generate a second growth when conditions improve, even after 2 weeks. These trees have genetically adapted to varying climate differences due to their wide range.
These trees do well in urban areas when they have sufficient space for their root systems. While it is more pollution-tolerant, its foliage in fall will not be as vibrant in urban environments.
These trees can be grown as colorful and vibrant bonsai. They are often used in the small-scale production of maple syrup, although the quality of sap changes due to their early budding. They are also harvested for lumber, with the wood being popular with custom furniture/musical instrument makers.
Native Americans used the bark to wash inflamed eyes and cataracts and as a cure for muscular aches and hives. They also brewed tea with the inner bark for treating diarrhea and coughs. Early pioneers made black and cinnamon-brown dyes from bark extracts and as ink after adding iron sulfate.
These trees can thrive under the direct sun but are also tolerant of partial shade.
They prefer moist soil but can also grow in dry soils if watered regularly. Once the tree is established, ensure it gets good watering every week. Prevent the soil from becoming dry by mulching the soil.
This plant is tolerant of a variety of humidity levels.
While it does require cooler weather, it is a hardy tree and can tolerate temperatures between 32-80oF.
This tree prefers to grow in acidic or neutral pH soil and won’t grow well in alkaline soil, producing stunted growth and pale leaves. It also cannot tolerate salty soils.
When growing this plant indoors, repot it every 2 years, during early spring or late fall. When repotting, cut down the roots to keep them small and move them to a larger pot with fresh soil.
These trees are easily propagated from seeds or by cuttings. These trees produce plenty of seeds that should be collected when they start dropping from the tree. Cuttings from mature trees are difficult to root but are still a viable method to propagate the tree.
Prepare a few pots with good drainage and fill them with soil. The pots should be big enough to give the seedling space to grow before it can be transplanted. Collect the seeds when they are fully mature.
Plant each seed in the individual pots, burying them 1-2 inches into the soil. Move them to a sunlit location, and water regularly without over-saturating the soil. Seeds will typically begin germinating after 10 days.
Prepare a few pots that drain well and fill with soil amended with perlite and peat. Select a healthy growing shoot after the tree has finished seeding and take a cutting between 6-8 inches long.
Remove the leaves from the lower half of the cutting. Make an inch-long shallow incision on both sides of the cutting’s base and coat the incisions with rooting hormone.
Bury the end in the prepared pot and water lightly. Place the cutting in a sunlit location and water regularly without drenching the soil. Prevent the remaining leaves from drying by misting them regularly.
Fertilization isn’t generally needed, but regular fertilizer can be used in spring.
Pruning is not necessary outdoors, but if you’re cultivating this fast-growing tree indoors, then it needs regular pruning to keep it to a manageable size.
Aphids, scale, and borers are a few pests that might plague these trees.
The bulk of the diseases that affect this tree are mostly cosmetic, generally affecting the leaves, although some infections can attack internally and kill the tree through the roots.
Verticillium wilt infects the circulatory system through the roots and prevents nutrients and water from getting to the leaves and branches. Infected dead leaves will drop to the soil, potentially spreading to other trees.
Symptoms include yellow, wilting leaves, leaf loss, stunted leaves, and discolored wood under the bark. There is no cure, although with proper care the tree can recover. This typically happens in summer. Mildly infected trees usually slowly decline, while more severely infected trees must be destroyed and the soil should be fumigated.
Root rot is common in wet and poor drainage conditions. This attacks healthy tissues and comprises the circulatory system, preventing nutrients and water from reaching the leaves and branches. This is commonly caused by fungal infections from wet soil and is fatal for the tree.
While tar spot isn’t life-threatening, this fungal infection affects the leaves, causing yellow and black spots and leading to leaf drops. There is no treatment for this other than prevention by collecting and disposing of infected leaves that fall off.
Anthracnose disease affects both leaves and branches and usually happens under wet weather conditions. Lower leaves and branches are more prone to infection. Symptoms include shriveled leaves, curled leaves, brown spots on leaves, and leaf veins becoming discolored. There is no cure – prune dead branches and remove fallen leaves.
Powdery mildew doesn’t harm the tree, as the powder simply sits on the leaves and can be removed using horticultural oil or brushed off. The roots will not be affected and the fungus doesn’t damage the leaves.
Leaf scorch usually occurs in summer, under hot and dry conditions, when the tree cannot provide sufficient water to the leaves. Increase watering, add mulch to sustain moisture and prune dead branches.