How to Grow and Care for Cucumber Trees

Cucumber tree branches with large yellow-green flower blossoms

The Spruce / Evgeniya Vlasova

The cucumber tree (Magnolia acuminata), also known as the cucumber magnolia, is a very large, hardy deciduous tree that’s native to North America. The tree is known for its symmetrical growth habit with a wide, straight trunk and and pyramidal crown. Its large, oval to oblong leaves are a glossy yellow-green. And its soft bark is a dark gray-brown.

The tree bears small, tulip-like flowers in the spring, which aren’t as showy as many other magnolia species. The fruits that follow the flowers look like small, warty cucumbers, which is how the tree got its common name. The cucumber magnolia has a moderate growth rate and can be planted in the fall or spring.

Common Name Cucumber tree, cucumber magnolia
Botanical Name  Magnolia acuminata
Family Magnoliaceae
Plant Type Tree
Mature Size 50–80 ft. tall, 35–60 ft. wide
Sun Exposure Full, partial
Soil Type Loamy, moist, well-drained
Soil pH Acidic, neutral
Bloom Time Spring
Flower Color Yellow-green
Hardiness Zones 4–8 (USDA)
Native Area North America

Cucumber Tree Care

Cucumber trees are quite low-maintenance. They tend to form a nice shape on their own without major pruning. And they don’t typically have any serious problems with pests or diseases. However, they can be sensitive to pollution. 

Make sure your planting site has loose, deep soil to accommodate this tree’s vast root system. Young trees will need some protection from extreme temperatures, and they'll require regular watering. But once they’re mature, they’re largely hands-off plants. You just might need to water occasionally and minimally prune branches for shaping.

Cucumber tree with bare branches and large yellow-green flowers in garden

The Spruce / Evgeniya Vlasova

Cucumber tree flower with large white petals in sunlight closeup

The Spruce / Evgeniya Vlasova

Cucumber tree branches with reddish-green fruit pod surrounded by leaves

The Spruce / Evgeniya Vlasova

Light

This tree does well in full to partial sunlight, meaning at least a few hours of direct sun per day.

Soil

Cucumber trees can tolerate a variety of soil types, as long as there is good drainage. They prefer an organically rich, loamy soil with a slightly acidic to neutral soil pH

Water

Water young trees to keep the soil moist but never waterlogged. Established trees have some drought tolerance. However, they can suffer leaf scorch in hot, dry conditions. Plan to water weekly in hot weather if you haven’t had rainfall. 

Temperature and Humidity

Cucumber trees have good cold tolerance, especially compared to many other magnolia species. But they can be sensitive to heat. So be sure to keep them well watered in the warmer parts of their growing zones. Humidity typically isn’t a factor in their growth.

Fertilizer

Unless you have very poor soil, supplemental fertilization usually won’t be necessary. But you can side dress with compost annually in the spring to give your tree a boost.

Types of Cucumber Trees

There are several types of cucumber trees, including:

  • ‘Elizabeth’: This cultivar is known for having excellent cold tolerance. 
  • ‘Miss Honeybee’: This variety is more compact than the main species plant, reaching only around 20 feet tall and wide.
  • ‘Butterflies’: This cultivar produces large yellow blooms that are especially attractive to pollinators. 

Pruning

Pruning is a minor chore for this tree and is best done after the tree has finished flowering for the season. Simply trim off any misshapen or dead branches. And if you ever spot broken or diseased branches, prune them off promptly.

Propagating Cucumber Trees

Cucumber trees are most commonly planted from young nursery saplings. But it is possible to propagate them via stem cuttings. This will allow you to essentially clone a particular variety that you like. The best time to take a cutting is in the summer. Here’s how:

  1. Cut a softwood stem that’s around 12 to 18 inches long. Make your cut at a 45-degree angle just below a leaf node.
  2. Remove the foliage on the lower half of the stem. Also, remove any flowers or fruits. 
  3. Dip the cut end in rooting hormone.
  4. Plant it in a container filled with moist soilless potting mix. 
  5. Keep the container in bright, indirect light at around 75 degrees Fahrenheit. And maintain moist soil. Roots should take hold in about six to eight weeks.

How to Grow Cucumber Trees From Seed

If you want to try growing a cucumber tree from seed, first you’ll need to chill the seeds at around 40 degrees Fahrenheit for four months. This mimics winter temperatures. Simply put the seeds in a container of moist sand, and store them in the refrigerator.

In the spring once the temperatures reach around 70 degrees Fahrenheit, direct sow the seeds about 1/4 inch deep. Keep the soil evenly moist but never soggy, and you should see germination in about four weeks. 

Mulching around your seedlings can help to retain soil moisture and suppress weeds that would compete with them. Also, only expose your seedlings to dappled sunlight during their first year.

Potting and Repotting Cucumber Trees

It is possible to grow a young cucumber tree in a container, though this might stunt its growth. For best results, choose one of the smaller cultivars. The container should have drainage holes and provide several inches of extra space all around your tree’s root ball. A grow bag can be a good option because it will remain relatively light to move. Using a plant caddy also can be helpful.

Pot your tree in an organically rich potting mix with sharp drainage. You can amend the mix with compost to improve its drainage and nutrition. Make sure to keep your tree well watered but never in soggy soil.

If you see roots growing out of the drainage holes and/or popping up from the soil line, you'll know it's time to repot. The best time for this is in the spring. Choose a larger container that provides ample space around the tree's root ball. But note that cucumber trees prefer not to have their roots disturbed, so ultimately it might be best to plant your tree in the ground.

Overwintering

Cucumber trees don't usually need any special overwintering maintenance because they have such good cold tolerance. However, young trees can benefit from a wind break to protect them from strong, frigid winds.

How to Get Cucumber Trees to Bloom

The flowers aren’t necessarily the valued part of the cucumber tree, as they’re relatively small and can be hidden by foliage. The yellow-green, slightly fragrant blooms are bell-shaped and stretch a few inches long. They appear in mid to late spring, beginning once the tree is a little over a decade old. 

A rebloom in the season is not typical, and deadheading (removing the spent blooms) is neither practical for such a tall tree nor necessary. Just make sure to delay any pruning until after the blooming period has wrapped up, so you and the pollinators can enjoy the tree's flowers.

Common Problems With Cucumber Trees

Cucumber trees don't typically have problems when grown in conditions they like. However, difficulties with their environment can cause some issues.

Leaves Turning Black/Brown

In the fall, cucumber tree leaves turn a golden brown. So if you see a color change then throughout the tree, it’s probably just a natural occurrence. However, if it happens at another time during the growing season, it might be the result of very hot, dry weather. Make sure the soil never fully dries out, and give your tree some extra water during the hottest months. 

Leaves Turning Yellow

Yellowing leaves can be a sign of both overwatering or underwatering, along with soil drainage problems. Cucumber trees like a moderate amount of moisture. So make sure water drains away fairly quickly after irrigation and rainfall. And also ensure that you provide supplemental water during periods without rainfall. 

FAQ
  • How long can cucumber trees live?

    When grown in the proper conditions, cucumber trees can live for over a century.

  • Where should I place a cucumber tree outside my house?

    When selecting a growing site for your cucumber tree, consider its mature size. Eventually, its canopy will shade a wide span underneath it. So if you have plants growing in the area that need direct sun, you might need to pick a different spot for your tree.

  • What are alternatives to cucumber trees?

    If you're looking for a shade tree like the cucumber tree, there are several options to choose from. Consider the red maple, sawtooth oak, river birch, or tuliptree.

Article Sources
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  1. Cucumber Tree. Illinois Wildflowers.