Acer rubrum

Updated: Jul 21


Acer rubrum, or red maple, is a highly sought after tree for fall color...if living in New England is your thing. The color is intense when autumn's cold snap begins, and when seen as an entire forest, people travel from all over to experience Mother Nature's brilliance, even if it only lasts for a few brief weeks. In California, however, generally, fall color can be visually subtle but last for months, despite planting a few red maples.


For example, fall begins in early summer, and at times of drought, Aesculus californica starts its slow descent into dormancy, turning its leaves from yellow to russet before falling. The season continues all the way through winter holidays with other species, namely native oaks, sycamores, and several shrubs including poison oak sport a range of colors and intensities. If you are fortunate to find a stand of native aspens in their golden moment, then you are in for a treat. While Californians have added red maples into the garden or street tree mix, it just does not perform as well outside of its native habitat without the supplemental addition of water.


Native to the East Coast, A. rubrum receives copious rain, including during the summer months. They thrive in particularly moist areas such as along streambeds or low spots where water pools. In their native forest habitats, leaves collect at their feet, decompose, and provide nutrients back to their shallow roots. In California, these shallow roots become a challenge in urban settings such as street tree locations where dry conditions persist.


For California's landscape architects, the challenge is to provide conditions that support red maples' long-term health if we want to enjoy their fall color for years to come. What happens, unfortunately, is that these shallow-rooted trees are placed in planters or tree wells with limited root space and inadequate water. The consequence could be damaged concrete, such as sidewalks, when surface roots search for water. Should designers plant red maples in the arid west? They do, regardless if conditions can support their use by supplying ample water and root space.


Red maples are well-suited for moist areas that do not require excessive supplemental water. For example, parts of a garden can remain moist due to lack of sun exposure, a spring, or heavier soils. These locations may be opportunities for planting, but designers should also be mindful that heavy soils like clay may also be a detriment. Planting in lawn is an option, but know the shallow roots may be an problem over time. Even if all the challenges are met, California's climate might not support the intense red fall color. Autumn can be outright hot, bleaching out any fall color. Cold snaps might not occur until after leaves have already fallen, if at all. So again, I ask, should designers plant red maples in the arid west? It certainly is feasible, so long as the expectation does not meet the fall blaze of New England.


West Valley College Campus Location: Acer rubrum

Language Arts/Social Science (east face)

Lat: 37°15'46.37"N

Long: 122° 0'31.74"W

facts

Botanical Name: Acer rubrum

Acer: Traditional Latin name for maple

Rubrum: Red leaves

Common Name: Red maple

Family Name: Sapindaceae


Origin: Central to Eastern North America


design considerations


Positioning: Woodland, lawn, riparian

Garden Themes: Shade, public park, autumn, country

Uses: Shade tree, specimen, street (with ample barrier free root space), accent


identifying characteristics


Type: Deciduous tree

Form: Oval to round, pyramidal (see specific cultivars for available forms)

Texture: Medium

Size: 40' to 60' wide x 40' to 60' tall (see specific cultivars for differing sizes)


Outstanding Feature(s): Fall color (leaf)


Bark: Dark brown to dark gray, exfoliating with age

Leaf:

  • Type: Simple

  • Arrangement: Opposite

  • Shape: Palmate, lobed

  • Margin: Serrate

  • Color: Medium green, slightly lighter underneath turning shades of gold, red to orange in fall (see specific cultivars for variation)

  • Surface: North Carolina State Extension aptly describes leaf texture as "slippery" due to its smoothness.

Flower: Spring. Medium to dark red, mildly showy clusters, slightly fragrant.

Fruit: Summer. Samara, red to brown.


cultural requirements, tolerances & problems


Sunset Zones: 1-9, 14-17

USDA Zones: 2-9


Light: Full sun to part shade

WUCOLS SF Bay Area Hydro Zone: Moderate

Soil:

  • Texture: Sand, loam, clay, well-composted

  • Moisture Retention: Moist but well-drained

  • pH: Slightly acidic to slightly alkaline

Tolerances: Brief heat or drought

Problems:

  • Branch Strength: Medium to weak

  • Insects: Aphids, borers, scale

  • Disease: Phytophthora, armillaria, root rot, verticillium

citations & attributions


Missouri Botanical Garden. "Acer rubrum." Accessed on June 28, 2021. http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=275374.


Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.


NC State Extension. "Acer rubrum." North Carolina State University, Raleigh. Accessed on June 28, 2021, from https://plants.ces.ncsu.edu/plants/acer-rubrum/.


Urban Forest Ecosystems Institute SelecTree. "Acer rubrum Tree Record." 1995-2021. Cal Poly State University, San Luis Obispo. Accessed on June 28, 2021. https://selectree.calpoly.edu/tree-detail/100.


Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on June 28, 2021.

https://ucanr.edu/sites/WUCOLS/Download_WUCOLS_IV_List/.


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