The Red Maple as Bonsai

by Jim Lewis

Introduction

The Species

• Close relatives: The maple family is widespread around the world. Palmer & Fowler note that "a number" of A. rubrum varieties are recognized, but go no further. Petrides notes one variety, A. rubrum trilobum. Nelson's Trees of Florida mentions no varieties.

• Range: Widespread, from S.E. Manitoba, east to Newfoundland, to South Florida and eastern Texas.

• Habitat: Wet to moist soils. Stream and pond banks, mesic forests, swamps and (sometimes) drier uplands. A common tree of mixed hardwood and floodplain forests.

• Leaves: Opposite. Size - 2 to 4 inches (in N. Fla. there is a variety with consistently small 1.5-inch leaves); quite variable in shape, mostly 3-lobed in my area (var. trilobum?), 3-5 lobed elsewhere; dullish green, with (usually) reddish leafstalk. They turn brilliant red, orange and yellow in fall (The north Florida variant with small leaves has generally dull-yellow leaf color in the fall). The reddish new leaves appear in late spring, as the maple seeds mature.

• Flowers: Small, showy red flowers begin to bloom in late winter or early spring (second week in February here in northern Florida) and bloom through March.

• Fruits/seeds also are red, and are winged. They occur in great profusion in late spring and early summer.

Bonsai Culture

• Propagation/source: Seed - 25-60% germination, according to "authorities." Based on the seedlings that appear in my yard each summer, 60% is the rule. Propagation from seed must be immediate, before the seed is allowed to dry out. They also propagate easily from cuttings. I have never tried to air layer one. Most of mine are from seedlings transplanted from the "wild" (underfoot).

• Potting and root pruning: Spring, as leaf buds turn a brighter red. This tree, when mature, is quite hardy and will suffer severe root pruning to no disadvantage that I can see. (However, I would not strip leaves in the same year as the severe root pruning.) Since this is a tree of usually wet to damp soils, the tap root is not well developed.

  Root pruning probably should be done every other year on a mature maple, but the amount of annual root growth will vary, depending on conditions, the pot, fertilization schedule, watering regime, and the individual tree. Younger trees and seedlings-in- training may be root pruned annually.

• Soil: Again, being a wetland tree by preference, the red maple will survive in (and may even prefer) a heavier, more water-retaining soil than other trees (or other maples). I use a similar organic compost mix (no gravel) for A. rubrum as for Bald Cypress, Taxodium distichum. They will, however, do quite well in a "normal" bonsai soil-- although in hot climates they may as a result require more frequent watering than other trees, or may need to be placed in a shallow tray of water). Normally, I do not keep red maples in water except during the hottest (above 95 degrees F) part of the summer.

• Pots: Maples in general seem to want more root underneath them than some other deciduous trees. A. rubrum is no exception. (Peter Adams in The Art of Bonsai notes that maples "must have root run", which I interpret to mean a slightly larger-than-normal-- deeper--pot for a tree of a given height or girth.)

  Dark, unglazed earth-tone pots are acceptable, but I prefer a white- or blue-glazed pot. Shape--oval or rectangle, depending on the styling of the tree. Here, though, your own tastes are paramount.

• Watering: Water copiously during the warm months, especially if the soil does not hold water. In hot climates (and especially in the arid west) keeping the tree in a shallow tray of water may be necessary.

• Fertilizing: Weekly, beginning in early spring; bi-weekly in fall until leaves begin to turn. Use a well-balanced fertilizer (10-10-10). I usually fertilize A. rubrum by placing the tree in a tray of water (up to the pot rim) in which fertilizer has been dissolved, and letting it be absorbed through the roots. (This is the only time I submerge my trees.) Do not fertilize immediately after root pruning.

• Winter care: Subject to local conditions, but this is among the hardiest of trees.

• Styling: Informal upright, slanting, clump, group and forest. I have never grown A. rubrum as a cascade or root-over-rock, since neither represents its "natural" growing habitat. This is not to say they cannot be grown that way.

• Wiring: The bark of A. rubrum--as other maples--is tender and scars easily. On the rare occasion that I do wire, I use unstripped aluminum wire. Since the natural growth habit of A. rubrum is to have ascending branches, forming a generally oval shape with a rounded top, wiring to pull down branches is not necessary. (Stowell (see below) notes that, because of its natural growing habit, ". . . this maple might introduce an American oval shape." Stowell's book is almost 20 years old now, though, and this doesn't seem to have happened. Alas.)

  I have wired A. rubrum to straighten a branch, or to edge it into a new position. In these cases, the wires must be watched carefully. Even rubber-coated aluminum wire will scar before a summer has passed.

• Pruning and Trimming: Pruning is the primary means of shaping A. rubrum. Pruning and leaf trimming can be used to increase the ramification of twigs, to induce branches to grow where none grow now, and to create valuable open spaces.

  Trim new growth by allowing 1 or 2 nodes to grow, then pinching back to 1. The more frequent and more severe the pinching back, the shorter the distance between the leaves and new branch nodes. (Sandy Vrooman has posted (several times) detailed and excellent instructions on pinching back maples. It should, by now, be in the Internet Bonsai Club FAQ. (I hope.)

  Major pruning should (as always) be undertaken with care. A branch, once removed, is difficult to replace. (Although you might be able to induce sprouting at the site of the scar, the resulting branch will be thin and awkward looking.) In the case of major branch removal, A. rubrum will repair pruning scars quite well if the cut is made flush with the trunk. I seldom use anything to seal the cuts.

  A. rubrum will endure leaf stripping (complete removal of leaves), but leave the leaf stem attached (it will fall of when new leaves appear). You also may cut leaves in half. I have seen no benefit from partial leaf stripping (stripping leaves from selected areas of the tree in an attempt to develop better twig and branch structure).

• Pests & other warnings: Aphids. White flies. Use the mildest pesticide you can find (that does the job). Leaves may burn in full sun, but not as easily as A. palmatum.

  See also: There is brief cultural reference to A. rubrum in Stowell's The Beginner's Guide to American Bonsai (page 125-6) where he lumps its culture/bonsai in with both A. palmatum and A. buergerianum. There are, I think, quite large differences.

  See page 7 of Petrides' A Field guide to Trees and Shrubs for a typical silhouette of the red maple.

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