Boxelder (Acer negundo) is actually a species of maple, but one that has limited value as a landscape tree due to a rather plain appearance and its habit of spreading invasively through self-seeding. A moderate-sized tree with an irregular crown, the boxelder has leaves that are somewhat smaller and shaped differently from other maples. The leaves are typically light green with three lobes (or sometimes five) that look like individual leaves—the leaf structure bears a resemblance to that of poison ivy. Unlike many maples, the leaves of the boxelder do not have a waxy surface and have a somewhat puckered texture. In the spring, in the spring the little "flowers" (buds) tend to fall after storms and can leave quite a mess on cars and streets. Female trees also bear small seed clusters a bit later in the season. Boxelder's fall color is undramatic.
Boxelder trees in the landscape very often begin as volunteer seedlings that sprout from seeds that fall from nearby trees. When planted deliberately, boxelder is usually planted as a nursery container or ball-and-burlap plant in spring. It is a very fast-growing tree, becoming a substantial tree with a 1-foot-diameter trunk within 10 years.
Boxelder seeds contain Hypoglycin A, which is known to cause a fatal muscle disease in horses, called seasonal pasture myopathy. This is not a tree you should grow in pasture areas.
|Botanical Name||Acer negundo|
|Plant Type||Deciduous tree|
|Mature Size||30–50 ft. tall and wide|
|Soil Type||Moist, fertile (but tolerates all soils)|
|Soil pH||Acidic to neutral (5.0 to 7.5)|
|Flower Color||Pale green (not showy)|
|Hardiness Zones||2–10 (USDA)|
|Native Areas||North America|
|Toxicity||Seeds are toxic to horses|
Boxelder's only real advantage as a landscape tree is that it grows very fast in almost any soil type, making it a good choice where you seek wooded cover very quickly. In its natural habitat, boxelder prefers moist soil, such as that found in river bottoms, so it can be a good choice for stabilizing ravine banks and stream edges. But be aware that once you have a boxelder as a landscape tree, you will likely be constantly dealing with aggressive self-seeding. The boxelder's tolerance for poor growing conditions makes it a bit of a nuisance. because it frequently sprouts up in unlikely or inconvenient places (like against the foundation of a house or next to a mature tree). It's best not to encourage these trees and to remove any suckers or young volunteer trees before they become more difficult to eradicate.
Boxelder requires little in the way of maintenance, but it is a messy tree with fairly brittle wood, so you will likely face considerable cleanup after storms.
Several states in the Midwest regard boxelder as an invasive species that threatens other native tree species. If you live in Michigan, Wisconsin, or Minnesota, it's wise to consult local experts before planting this tree in your landscape. Selected regions in other areas of the country may also discourage planting boxelder.
Boxelder trees prefer at least six hours of direct sunlight each day. They will not do well in deep shade.
The boxelder is tolerant of a wide range of soil conditions, which add to its tendency to be invasive. One soil condition it's not very tolerant of is salt—it is not likely to grow well in areas where salt or other melting compounds are used on roads and sidewalks in winter. Boxelder prefers acidic to neutral soil (5.0 to 7.5 pH).
Boxelder is naturally inclined to favor moist conditions, but it will readily adapt to short periods of drought. Long-term drought it may cause some weakening of the tree's branch structure, and denying the tree water is one method for controlling its rampant growth and spread.
If you have a boxelder that you view as a valuable landscape tree, make sure to water it during dry spells.
Boxelder generally does not need feeding. Fertilizing tends to make the tree grow even faster, often with weaker wood that is even more susceptible to wind damage.
Types of Boxelder
In many regions, you will have trouble finding even the species form of this tree offered for sale in nurseries. But there are several named cultivars of boxelder that you might be able to find, including:
- 'Flamingo' has new leaves with a pink hue, maturing to light green with creamy edges.
- 'Kelly's Gold' is a slightly shorter tree with yellow-green foliage.
- 'Variegatum' is another a variegated variety of boxelder.
- 'Winter Lightning' has bright yellow bark and uncharacteristically bright yellow fall foliage.
The boxelder tree puts out suckers very aggressively, making constant pruning necessary to keep it looking neat. In addition, the prodigious self-seeding means you will constantly be plucking out volunteer seedlings from your landscape—unless you wish to surrender your yard to a veritable boxelder forest.
If you're maintaining a mature boxelder tree, watch for diseased or broken branches and remove them to avoid having them break and fall. Also, be aware that ice and wind damage in the winter is a potential problem due to the boxelder's somewhat weak wood and loose branching structure.
Deliberately propagating boxelder trees is not a common goal, given its penchant for self-seeding so readily. Vegetative propagation by rooting softwood stem cuttings is a fairly easy but slow process—and it is the preferred method if you are trying to reproduce one of the named cultivars, such as a variegated variety. Here's how to do it:
- During the active growing season, use sharp pruners to cut 6- to 8-inch green tips from the ends of branches. Remove all but the top leaves.
- Dip the cut end in rooting hormone, then plant it in a small container filled with commercial potting mix. Dampen the potting mix, then place the pot in a loosely secured plastic bag to hold in humidity.
- Place the pot in a location with bright indirect light, and mist it regularly to keep the cutting moist. It will take several months for the cutting to root. You can test occasionally by tugging gently on the stem—when you begin to feel resistance, it means that roots are forming.
- After the cutting has developed a good network of roots and new green growth is starting, remove the plastic and continue growing the plant in sunny conditions. Repot the cutting into a larger pot as it becomes root-bound. It will likely take a year or more until the cutting is of sufficient size to plant in the landscape.
How to Grow Boxelder From Seed
A better topic might be "how to NOT grow" boxelder from seed. Dried seeds collected from a tree—or which simply fall into the soil beneath the tree—will sprout into volunteers very, very easily. Should you want to propagate the tree, simply digging up and moving one of these volunteers is very easily done.
Potting and Repotting Boxelder
Boxelder is a fast-growing tree that is not practical for container culture.
Boxelder requires no special protection against winter cold, though young trees may require protection from grazing animals, such as deer and rabbits, which can gnaw the bark. A cage of hardware cloth can protect the thin bark during the first couple of years.
Common Pests & Plant Diseases
The boxelder attracts a very specific pest called the boxelder bug. These harmless insects like to invade homes in the autumn, which makes them a bit of a nuisance. Boxelder trees are also susceptible to borers.
Anthracnose, powdery mildew, and canker may be occasional disease problems, but overall, boxelder is free of serious diseases.
How to Get Boxelder to Bloom
Boxelder trees do not have showy flowers, so there is no reason to encourage spring blooming. Because female trees are quite messy with their production of seeds, homeowners often opt for the neater male trees.
How do I get rid of a boxelder tree?
Boxelder can often be something of a nuisance in the landscape, sprouting up where you least want them. One trick they have is entwining with the roots of other young trees so that it may become confusing which tree is which. The boxelder's new branches and stems are always light green which can help identify new growth. Such trees can be difficult to eradicate, as they will readily sprout up unless you can extract the roots. If a young tree is too deeply rooted to dig out, try cutting it back and taping it with duct tape to prevent sun exposure. This can weaken the root system and make it easier to remove over time.
- It may be possible to systematically kill a boxelder by denying it water and sunlight over a period of several years.
- Herbicide containing the ingredient imazapyr will kill a boxelder tree if it is injected into holes bored into the trunk—a procedure best done by a professional. Some of the most popular standard herbicides, such as 2, 4—D or glyphosate, do not work very well on boxelder.
How long does a boxelder tree live?
Boxelder is a moderately long-lived tree with a typical lifespan of 60 to 75 years. However, new suckers often resprout from stumps of old trees, and may continue to do so for a century or more.
What is the difference between male and female boxelder trees?
Boxelder is a dioecious plant, which means individual trees produce male or female flowers, but not both. It is the female tree that produces seeds in the form of clusters of "helicopter" samaras. A female tree can be quite messy, so it is often the male trees that are offered for sale in the trade.