How to Grow and Care for 'Red Sunset' Maple

"Red Sunset" maple is the trade name for a popular cultivar ('Franksred') of the native red maple tree and it has similar cultural needs to that native North American tree. It has smoothish gray bark that gradually darkens with age, and the leaves have the familiar 3 or 5-lobe maple structure, dark green on the top surface and gray-green on the bottom. This cultivar is grown for the richness and reliability of its fall foliage color (turning from green to brilliant red) and for its cold hardiness. The mature size the tree attains (a manageable 40 to 50 feet) is also more predictable than it is for the native plant, which is an important consideration for homeowners with small yards who need assurance that a tree is not going to overwhelm their properties.

'Red Sunset' maple is a moderately fast grower that typically adds 12 to 24 inches per year. It is best planted in the late fall or the early spring.

'Red Sunset' Maple Care

'Red Sunset' is normally planted as a potted or ball-and-burlap sapling in spring or fall. Plant it in a sunny location with plenty of space to accommodate its adult size. It prefers rich, moist but well-drained soil with an acidic pH. A low-lying area that is frequently moist can be a good spot for this tree. Plant it at the same depth it is growing in its nursery container, in a large hole that is well prepared with any necessary amendments—which can be especially important if the soil is not sufficiently acidic. As with any tree, it's a good idea to get a soil analysis to determine if the site is suitable for this species.

A 2- to 3-inch layer of mulch over the root zone will help keep the root system cool and retain the moisture that is craved by this tree, but make sure the mulch does not come into contact with the trunk, which can invite pest and disease problems.

Light

At the northern end of its range, give 'Red Sunset' maple full sun to promote optimal fall leaf color. At the southern end of its range, it can take partial shade.

Soil

'Red Sunset' maple likes moist soil that is rich in nutrients, with a pH value that is slightly acidic. Soil amendment and regular mulching with an acidifying material, such as peat or pine needles, can help acidify soils that need it.

While this tree likes moist soil and will even tolerate being in standing water for short periods of time, over the long run it will perform better in soil that drains well.

Water

'Red Sunset' maple has above-average water needs and its soil must be kept evenly moist. About 1 inch of water each week, through a combination of rainfall and irrigation, should be considered the minimum. A thick layer of mulch over the root zone can help preserve soil moisture.

Fertilizer

'Red Sunset' should be fed at planting time with a granular slow-release fertilizer, which is less likely to burn the tender young roots. Make sure to thoroughly blend in the fertilizer with the fill soil. Thereafter, feed 'Red Sunset' annually in early spring with a fertilizer meant for acid-loving plants.

Types of Red Maple

'Red Sunset' is one cultivar among many developed from the native red maple, Acer rubrum. Other popular red maple cultivars include:

• 'October Glory' is similar to 'Red Sunset', but it grows somewhat faster.
  
• 'Autumn Blaze' has a nicely rounded form and delightful long-lasting orange-red fall foliage.
• 'Burgundy Bell' is a smaller tree with unusually dark purple-red fall leaves.
• 'Scarlet Sentinel' is a columnar variety, a fast-growing tree with yellow-orange fall foliage.
• 'Schlesingeri' is a fast-growing variety with deep-red autumn leaves that remain on the tree for an exceptionally long time.

The advantage in growing cultivars of red maple rather than the native tree is that the performance of the former is more predictable. The cultivars achieve the desired red fall color more reliably than do the native plants, which may display yellow instead of red foliage under certain conditions.

Pruning

The only mandatory pruning with 'Red Sunset' maple is to remove damaged or diseased limbs as you notice them. And it's also a good idea to remove branches where necessary to eliminate very narrow angles between the trunk and side branches, as these crotches can be notoriously weak and subject to wind damage. All red maples are sensitive to pruning, so it's best to avoid cutting large branches if possible. Make your cuts just outside the branch's collar, which will make it easier for the tree to heal its wounds.

Pruning is best done in late summer through mid-winter, as the trees are likely to bleed sap if pruned at other times.

Propagating 'Red Sunset' Maple

The 'Red Sunset' cultivar was developed by selection of particular red maple bred to have desirable traits, which was then propagated by root cuttings for commercial sale. Virtually all commercially sold 'Red Sunset' maples are vegetative root clones of that first tree, carefully selected in 1966 by J. Frank Schmidt and Son company in Oregon.

Growing new plants from root cuttings is a difficult method of propagation for amateurs, so it is rarely attempted. You can, however, attempt to reproduce a tree through seeds. But be forewarned that the result may not be an exact match to the parent tree. If there are other red maples in your area (native species or other named cultivars), cross-pollination may create seeds that produce a different-looking tree. But if you want to try seed propagation, here's how to do it:

1. Collect seeds from a mature red maple tree in late spring or early summer. Select seed pods that are beginning to turn brown and break them open to remove the seeds.
2. Fill a well-draining 8-inch pot with a commercial potting mix. Plant the seeds 1 to 2 inches deep, moisten the soil mix, then place the pot in a sunny location.
3. Water the pot regularly, keeping it uniformly moist but not soggy. The seeds usually germinate and sprout within 10 days.
4. Continue growing the seedling tree in a sunny location until planting time. Seeds started in spring will often be ready for landscape planting in the fall. Or, you can place the pot in a sheltered outdoor location (a cold frame, for example) through the winter, then continue to grow it for another season before planting it.
   

Overwintering

Red maples are extremely cold-hardy trees that need no protection against the cold through winter. But young trees have bark that is quite thin, so protection with tree guard fabric will help prevent sunscald and frost cracks. After several years, this protection will no longer be necessary.

Guard against damage from deer, rabbits, and other gnawing animals by protecting the trunks of young trees with hardware fabric or another type of guard for the first few years as the tree is becoming established.

With established trees, it's a good idea to withhold feeding as fall approaches, as the tree is naturally leaning toward dormancy at this time. Any serious pruning that is needed is best done during the tree's dormancy period, before sap begins to flow in late winter.

Common Pests & Plant Diseases

Among the worst pests affecting 'Red Sunset maple are aphids, borers, caterpillars, leafhoppers, and scale. Its chief disease problems are canker, fungal leaf spot (including anthracnose), root rot, and verticillium wilt.

The pests can often be eradicated by using neem oil. Unfortunately, the disease problems are not as easy to solve (after the fact) and are best addressed through prevention. Some preventative techniques include optimal site selection, spacing to promote airflow, and a proper watering regimen.

How to Get 'Red Sunset' Maple to Bloom

This is not a tree grown for its flowers, so there is no reason to fret if your tree does not produce the small tufts of red flowers in spring. Young trees typically do not flower and produce seeds until they are four to eight years old, and the appearance of flowers and seeds marks the point where the tree becomes a bit messier to care for, with lots of seeds that must be raked up each spring.

Common Problems With 'Red Sunset' Maple

'Red Sunset' and other cultivars are somewhat less susceptible to problems than the native species, but you still may notice some of these issues:

Fall Color Is Disappointing

Though 'Red Sunset' maple trees offered commercially are root clones that normally will produce a reliably deep red fall color, this is not guaranteed to occur every year. Unusual weather conditions can cause your tree to display disappointing yellow foliage during some years. It's also possible that your tree was not the pure clone it was advertised to be. The expected fall color for 'Red Sunset' can range from orange-yellow to a deep purple-red, and it's not uncommon for the color display to vary from year to year.

Leaves Are Covered With Dark Spots

This symptom is generally a sign of infection from anthracnose or another fungal disease. While they are unsightly, leaf spot diseases are not very harmful to the tree and it's usually best to avoid treatment. Cool, wet spring weather is more likely to bring on leaf spot diseases, and as affected leaves drop, the tree's canopy may become rather sparse until it recovers. In some climates, anthracnose and other fungal diseases are a nearly annual occurrence.

Branch Tips Are Dying Back

New tip growth that immediately turns black and then falls from the tree is a condition known as scorch, which for red maples is usually caused by a lack of moisture rising up to the new growth from the roots. It's important for red maples to get plenty of spring moisture as this new growth is developing.

Dieback of entire branches, usually beginning at the top of the tree, is sometimes a problem with maples, though it occurs more often with sugar maples (Acer saccharum) or sugar maple hybrids than with red maple. Tree dieback usually is the result of overall poor cultural practices.

Surface Roots Are Disrupting the Lawn

Most maples have relatively shallow roots that can eventually disrupt a smooth lawn or even cause sidewalks or driveways to heave. This is why it is best to plant them well away from any paved surfaces. If a maturing tree begins to disrupt your lawn with its exposed roots, the best strategy may be to convert the area beneath the tree canopy to a planting area covered with a good layer of mulch that hides the exposed roots.