Plants

Boxelder

Acer negundo

Folkert Siemens Folkert Siemens

Boxelder impresses with variegated varieties that are also suitable for smaller gardens due to their compact size. Tips for planting and care.

Growth type
  • Deciduous wood
  • Tree
  • large shrub
Growth height (from)
from 1200.00cm to 1500.00cm
Growth width (from)
from 1000.00cm to 1200.00cm
Growth characteristics
  • spherical
  • sweeping
  • loosely
Flower color
  • yellow
  • red
Flowering time (month)
  • March to April
Flower shape
  • Cluster
Flower characteristics
  • unfilled
  • monoecious
Leaf color
  • green
page format
  • feathered
Sheet properties
  • Autumn coloring
Fruit color
  • brown
Fruit shape
  • nut fruit
  • Fissile Fruit
Fruit characteristics
  • long lasting
  • Self-seeding
Light
  • sunny to semi-shade
Soil type
  • sandy to clayey
Soil Moisture
  • dry to wet
ph value
  • alkaline to weakly acidic
Lime compatibility
  • lime-tolerant
Nutrient requirements
  • moderately nutritious
Decorative or utility value
  • Flower Decoration
  • Leaf ornaments
  • Nectar or pollen plant
Toxicity
  • non-toxic
Winter Hardness
  • hardy
Climate zones according to USDA
  • 4
Use
  • Floor mounting
  • Single position
  • house tree
  • Pioneer tree
  • Street greening
  • Windbreak
Garden style
  • patio
  • Park area
  • Forest Garden

Origin

Boxelder (Acer negundo) is native to eastern North America. It grows there in moist to wet soils on the shores of lakes and in riparian forests. It is one of the most commonly planted foreign trees and, as a neophyte, wild-growing populations are found in some regions.

Growth

Boxelder usually has a multi-stemmed growth form. It develops a loose, broad, rounded crown, and can grow 50 feet tall and 30 to 40 feet wide with age. The main branches have a very sprawling growth habit. They protrude almost horizontally at the bottom and the branches hang down slightly. Boxelder grows very quickly as a young plant and can get up to three feet taller each year.

Leaves

The opposite leaves of Boxelder do not have the typical lobed appearance of maple leaves, but—like ash trees—are odd-pinnate compound, and usually have three or five (in rare cases seven) light green leaflets. However, these are sometimes slightly lobed. The leaves of Boxelder turn yellow in fall, sometimes even shining in orange colors.

Flowers

The flowers of Boxelder open before the leaves sprout in March. The plants are monoecious, meaning that they have both female and male flowers. The male flowers in particular are highly ornamental, the stamens of the grape-like flowers hanging down in clusters on long yellow to reddish stalks. The female flowers are also grouped in clusters and have large yellow to reddish carpels.

Fruit

The small winged fruit of Boxelder have a reddish color at first, later turning pale yellow to beige, sitting in clusters in the leaf axils of the branches. In the botanical world, they are known as nutlets. The wings form a remarkably acute angle.

Flowers (left) and fruits (right) of the Boxelder

Location

Boxelder feels at home both in the sun and in partial shade. It is very frost-hardy and therefore also does well in colder locations. However, it also needs some protection from the wind as the branches of older trees can be damaged by strong winds. Dry urban climates and polluted air are not a problem for boxelder.

Soil

As a pioneer species, Boxelder can cope with almost any soil. It grows in moderately dry, poor sandy soils and also in loamy, wet soils with a high water table. It prefers slightly acidic substrates but tolerates lime.

Planting

Leave plenty of space for Boxelder as the tree will grow to a considerable size in the garden. The tree is low maintenance so there is no need to prepare the soil. Garden paths in the root area should be bordered with edging stones supported by backing concrete, otherwise the roots close to the surface may damage the paving.

Care

Boxelder does not require any special care. However, freshly planted trees should be watered regularly in dry conditions. Do not use fertilizer, as a good supply of nitrogen can make the wood even more brittle than it already is.

Pruning

While the Boxelder is tolerant of pruning, it does not need to be pruned regularly. You should particularly avoid heavy pruning of the main branches as the points where new shoots emerge are very fragile throughout the tree’s life. If the crown becomes too big, whenever possible, the branches should be pruned back to the existing stronger side shoots and not simply cut off. Like all species of Maple, if you need to prune boxelder, the best time to do this is late summer as the pruning cuts bleed heavily in spring.

Use

The variegated forms of Boxelder are particularly popular house trees as they have a weaker growth habit and do not grow tall like the wild species. In the USA, Boxelder is also used as a pioneer species for afforestation measures in the open countryside. However, this should be avoided in Germany as the tree is not native to this country. When it comes to underplanting the trees, the only suitable options are shrubs and trees that can tolerate high root pressure, as boxelder roots heavily penetrate the topsoil. However, the light crown of the trees allows plenty of sunlight through, so species that need a little more light can also grow below the tree.

Boxelder ‘Kelly’s Gold’ (left) and ‘Violaceum’ (right)

  • ‘Aureo-Variegatum’: blue-green frosted bark; yellow-green variegated leaves; 23 to 33 feet tall and 13 to 20 feet wide
  • ‘Flamingo’ (large picture at the very top): white to pink-white margined and marbled leaves with gray-green base color; 16 to 23 feet tall and 13 to 20 feet wide; also suitable for planting in containers
  • ‘Kelly’s Gold’: foliage emerges golden yellow, later light green leaves; light yellow fall color; 16 to 23 feet tall and 13 to 17 feet wide
  • ‘Variegatum’: leaves emerge pink, later green and irregular white margins or bands; approx. 23 feet tall and 13 to 17 feet wide
  • ‘Violaceum’: variety with vigorous growth habit; grows to about 50 feet tall and 40 feet wide; foliage emerges dark red, turns green in summer; very dark, bluish frosted bark

Propagation

Wild species of Boxelder can be propagated by seed, cultivars are generally propagated by budding. With this grafting method, a bud of the cultivar is grafted onto the bark of the seedling rootstock. With a little bit of luck, it is also possible to propagate the tree from hardwood cuttings: Take hardwood cuttings from the current season's shoots in early winter and put them in a shady spot in the garden in moist humus-rich soil. With this method, the rooting percentage is around 10%, so you need to take plenty of hardwood cuttings to be successful.

Diseases and Pests

Boxelder is somewhat susceptible to fungal diseases. This includes, among others, powdery mildew, which causes a white powdery coating to appear on the leaves. In terms of pests, the Boxelder is occasionally affected by the leafcutter bee. They make small holes in the leaves but do not cause any lasting damage to the tree, so pest control is not necessary.

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