Cucumber tree (Magnolia acuminata) is a deciduous tree native to eastern North America. The largest varieties of cucumber tree grow in the southern Appalachian Mountains. This species produces sweet-scented, greenish-yellow blossoms that are reminiscent of a tulip. The tree is named for the cucumber-like seed cones that appear after its blossoms fall off.
I. Appearance and Characteristics
Magnolia acuminata, commonly called the cucumber tree (often spelled as a single word “cucumbertree”), cucumber magnolia or blue magnolia, is one of the largest magnolias, and one of the cold-hardiest. It is a large forest tree of the Eastern United States and Southern Ontario in Canada. It is a tree that tends to occur singly as scattered specimens, rather than in groves.
The cucumber tree is native primarily within the Appalachian belt, including the Allegheny Plateau and Cumberland Plateau, up to western Pennsylvania and New York. There are also numerous disconnected outlying populations through much of the southeastern U.S., and a few small populations in Southern Ontario. In Canada, the cucumber tree is listed as an endangered species and is protected under the Canadian Species at Risk Act. In 1993 The North American Native Plant Society purchased Shining Tree Woods to preserve a stand of Magnolia acuminata, which is also known as “The Shining Tree”.
The leaves are deciduous, simple and alternate, oval to oblong, 12–25 centimetres (4.7–9.8 in) long and 6–12 centimetres (2.4–4.7 in) wide, with smooth margins and downy on the underside. They come in two forms, acuminate at both ends, or moderately cordate at the base (these are usually only formed high in the tree).
Unlike most magnolias, the flowers are not showy. They are typically small, yellow-green, and borne high in the tree in April through June. The leaves of Magnolia acuminata are pointed at the tip and provide it with its name – ‘acuminate’ means tapering to a fine point. The name “cucumber tree” refers to the unripe fruit, which is green and often shaped like a small cucumber; the fruit matures to a dark red color and is 6–8 centimetres (2.4–3.1 in) long and 4 centimetres (1.6 in) broad, with the individual carpels splitting open to release the bright red seeds, 10–60 per fruit. The ripe fruit is a striking reddish orange color.
II. How to Grow and Care
Sunlight
The positioning of your cucumber tree is also an important consideration. Despite being able to cope with cooler climates, they will prefer a sunny spot in the garden with some partial shade for protection during the summer months.
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.
Watering
Cucumber tree should only need watering as younger, newly planted trees, or during periods of drought. If a cucumber tree is planted in the garden, it should be watered immediately after planting, and again when the water has seeped through, and repeated 4-5 times. Water it a second time 3 days after planting and a third time 5 days after planting.
After that, watering can be sparingly done, and established plants can absorb moisture from the soil. Pay close attention to checking if they survive. In the hot seasons, a little water can be used in the morning and evening, while in other seasons it is not necessary.
Soil
Cucumber tree prefers acidic soils, which is important to consider if you are gardening in alkaline soil such as clay or chalk. Add a layer of peat when planting your cucumber tree to help raise acidity levels. In areas where soil remains wet, particularly during the winter months, this is no reason to worry: cucumber tree can happily cope with compact, rich soil.
Fertilizing
Organic fertilizer should be applied to the base of the plant in spring. At this time of year, your cucumber tree will just be starting to develop leaves and will want extra nitrogen to help with their production. This gives plants the energy to bloom a little later in the season. Therefore, a nitrogen-rich fertilizer such as dried-blood meal is recommended.
Later in the year, and particularly if your region has had heavy rain over the growing season, cucumber tree benefit from a lighter feed of fertilizer to help return vital nutrients into the ground. A fertilizer with potassium, such as potash, is suitable at this time of year and can be applied during fall before the tree becomes dormant over the winter.
Pruning
Cucumber tree requires little pruning. In fact, pruning can harm the trees or prevent flowering if pruned back too hard. Therefore, a light trim of younger trees during late spring/summer after they have finished blooming is all that is recommended to help shape your plant and to encourage more blooms in the coming years. Remove any damaged branches and ones that are crossing over. You can also trim back any extra-long, leggy shoots. Consider the tree shape when pruning your cucumber tree, and always aim for a balanced, open structure.
Propagation
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:
- 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.
- Remove the foliage on the lower half of the stem. Also, remove any flowers or fruits.
- Dip the cut end in the rooting hormone.
- Plant it in a container filled with moist soilless potting mix.
- 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 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
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.
Pests and Diseases
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.
III. Uses and Benefits
- Ornamental uses
Cucumber tree provides year-round interest: in the spring, a treeful of lightly fragrant yellow blooms; in summer, cucumber-like fruits dangling from every branch; fall, colorful foliage; and an interesting shape in winter. Cucumber tree is a gorgeous option for a shade tree or specimen piece in a larger-sized lawn or garden.
- Other uses
In the timber trade, the wood of this tree is interchangeable with that of the related tuliptree (Liriodendron tulipifera).
Magnolia acuminata has been used in hybridizing new varieties that share its yellow flower color and cold hardiness.
It additionally has been marked as a pollinator plant, supporting and attracting bees and butterflies. It is a host plant for butterflies, providing food during their larval stage.
