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Botanical Name – Acer rubrum
Botanical Name – Acer rubrum
Common Name – Red Maple
Picture provided by Cat Nelson (A. rubrum var.drumondii) US National collection
Native to – Eastern North America from Canada to Florida
Botanical Information – First described by Carl Linnaeus in 1753. Acer rubrum is a deciduous tree with leaves that are 3-5 lobed and range in size from 4-6 inches wide. The tree is considered to be a “variable” species, meaning that seedlings can vary widely in growth habit and general foliage appearance. There have been many identified natural varieties such as “var. drumondii” and subspecies such as “subsp. carolinianum” , etc… which are under scientific review as to their familial relationships. From a bonsai perspective, all varieties and subspecies can be treated identically to the species. This tree is Polygamodioecious, meaning, bisexual with male flowers on some plants, with bisexual and female flowers on others. Male trees will be more vigorous in growth. However, female trees will not only give you the lovely spring time flowers like the Males but seed (samara) as well, to enjoy before the leaves appear.
General - This is the predominant maple in the Eastern United States. However, it is not used for bonsai nearly enough given the amount of material available. This maple in nature is very adaptable to many environments and will be found in low bottom lands rich in clay and water as well as higher dry, rocky ground and everything in between. Collection of specimens is rather easy but often the larger specimens experience dieback on the main trunk within the first year of collection. While the leaves are rather large in general, soil mix, pinching, and leaf pruning can all have an affect on the size of the leaf for trees under bonsai cultural conditions. Internodes will vary from large on a vigorous new shoot to very small on a tightly ramified branch. Vigorous pinching is required to maintain good branch structure. Red maple will not only make a wonderful tree during the summer months with bright green leaves, but will also put on a lovely display of fall colors of yellow to red-orange. From my perspective the best time for this tree is in the early spring when it puts on a wonderful flower display of bright red flower bundles before the leaves emerge.
Cultivars - Many cultivars have been selected for landscape purposes. However, they have not shown any superior bonsai features when compared to the native species.
Red maple should be grown in the full sun for the majority of the growing season to keep the foliage from becoming overly large. Some light shade on the hottest afternoons of mid-summer would be appreciated. For those in the desert south west where there is bright sunlight in rather dry conditions for most of the growing season, full morning sun with light shade after mid-day would be the best of situations for this tree.
Red maple is quite adaptable to variations in temperature and will perform well in both extreme heat and cold. It is cold hardy when grown in the ground from Newfoundland in Canada to the swamps of Florida. Plants should be selected from your local area or from an area with seasonal conditions close to yours. Trees from southern locations are not cold hardy in the North. For trees grown in containers some minimal winter protection in US growing zones 5 and lower is recommended. Winter protection can be as minimal as placing the tree in a North facing position and covering the tree roots with two to three inches of dried pine needles . A cold enclosed room is even better.
Like most maples, Red maple enjoys having their roots in abundant moisture. Since they are adaptable in where they grow naturally, they can endure both swamp conditions as well as a rough dryer terrain. This should give some guidance on your watering regimen. For most, a single watering will suffice during the early part of the growing season but an afternoon watering may be in order when the humidity is low and afternoon temperatures rise above 80 degrees F. If you’re going to be away for a few days, placing the tree in a container of water that covers the container completely will do no harm.
Any complete fertilizer applied at the recommended dosage is fine. If your soil mix is rather free draining, ferterlizing every 2 weeks would be in order. An application of a dry slow release mixture of blood meal and bone meal in the early spring will help to even out nutritional needs of the tree.
Any pruning of large branches or trunks should be done at least 60 to 90 days prior to the onset of spring bud swelling to minimize bleeding. Red maples are one of the maples used in the production of maple syrup and are known to bleed profusely and if pruned at the incorrect time can bleed to death. Small branches may be pruned at just about anytime of the year without harm. Under normal growing conditions red maple has rather large internodes and getting them to ramify properly on vigorously growing shoots requires letting them grow 4 or 5 internodes and then cutting back to the first internode. This is a constant task during the early spring growing season. This process of constantly pruning back the growth encourages dormant buds to pop along the branch which are smaller (shown above) and helps develop full pads of growth. Buds can develop in any direction on a branch so removal of those that grow from the bottom of the branch should be removed immediately. Leaf pruning can be done during the summer to encourage smaller leaves.
Wiring should be done in the late fall when half or more of the leaves have dropped off of the tree. There is still enough sap in the wood to allow for the branch to be moved without fear of breakage. As the winter progresses the tree will expel most of the sap from the branch and the wood will harden into position. Summer wiring may be done if you watch it closely. The time period just after the spring growth has hardened off is when this tree begins to put on girth and branches with wire will girdle rapidly.
Repotting should be done every two or three years. The roots of this tree are very vigorous and can be pruned quite hard. Small feeder roots are easily produced when the larger structural roots have been cut back. For trees that have been containerized for a few years, and had their structural roots pruned back so that the majority of the remaining roots are feeder roots, a typical repotting removal of 1/3rd of the root mass would be about right. Surface roots to create nebari should be encouraged by bringing them up to the surface and letting the sunlight hit them. This will cause those roots to gain girth and bark-up faster than if they were covered by soil. Because of this trees accommodating growing conditions, soil can be almost any mixture. Soils that are free draining with little humus but sufficient clay to retain moisture will encourage smaller growth.
Propagation is normally accomplished using seed. Seed are produced in the spring and should be planted immediately upon ripening. Late summer cuttings can also be taken when the new growth has hardened off and the wood is considered “half-hard”.
Pests and Diseases
Loopers, spanworms, the gall making maple borer, maple callus borer, Columbian timber borer, and various scale insects are common in the wild. Under container culture this tree is rather pest free. A normal summer spraying program will usually avoid most pests. Inspect the branches of this tree for scale prior to putting them away in their winter location.
|April 2008||February 2010|