This native Asian tree was planted widely around the US for erosion control. It fruits in bountiful clusters of flavorful, silver-spotted red berries. Unfortunately, autumn olive has outcompeted many local plants and is now considered an invasive species in North America.
I. Appearance and Characteristics
Elaeagnus umbellata is known as Japanese silverberry, umbellata oleaster, autumn olive, autumn elaeagnus, spreading oleaster, autumnberry, or autumn berry. The species is indigenous to eastern Asia and ranges from the Himalayas eastwards to Japan. It is a hardy, aggressive invasive species able to readily colonize barren land, becoming a troublesome plant in the central and northeastern United States and Europe.
Elaeagnus umbellata grows as a deciduous shrub or small tree, typically up to 3.5 metres (11 ft) tall, with a dense crown. It commonly bears sharp thorns in the form of spur branches. Flowers are fragrant, occur in clusters of white to yellow, are 8–9 mm in length and 7 mm in diameter, and have four lobes.
The leaves are alternate, 4–10 cm long and 2–4 cm wide, with wavy margins. The leaves are covered with minute silvery scales when they emerge early in the spring but turn greener above as the scales wear off during the summer. The underside is more intensely covered in the silvery scales, differing from the related E. angustifolia, which remains silvery until it sheds its leaves in the fall.
- Flowers
The flowers are borne in the leaf axils in clusters of 1–7. They are pale yellowish-white, fragrant, (often heavily fragrant) and have a four-lobed corolla 1 cm long. They are an important source of nectar for pollinators such as bees.
- Fruit
The fruit is a small round drupe 1/4 to 1/3 inches (0.65 to 0.85 cm) in diameter. The unripe fruit is silvery-scaled and yellow. It ripens to red, dotted with silver or brown. The ripe fruits are pulpy, juicy and sweet, 3–9 mm in length, 5 mm in diameter, and average 137 milligrams in weight, with a thin skin covering the whole fruit. Having a sweet and tart flavor, the berries can be eaten fresh or processed for jam, condiments, flavoring, or used as a substitute for tomato. When mature, the red berries contain carotenoids, including considerable amounts of lycopene.
- Naturalization
In its origin regions of tropical and temperate Asia, E. umbellata is not considered to be an invasive species, but in many world regions, it has become invasive across wild and cultivated areas, particularly in the eastern United States. In the early 19th century, E. umbellata was purposely introduced to the United States and the United Kingdom for shelter belts, erosion control, wasteland reclamation, wildlife habitat, and for gardens as an ornamental. By the late 20th century, the shrub became a noxious weed and invasive species in many US states from the east coast to the central prairies, and spread widely across Europe.
Due to its substantial seed production and avid germination potential, E. umbellata rapidly invades new areas where it can resprout readily after burning or cutting. Because E. umbellata stands are habitats for wildlife, such as providing forage and shelter for deer, nesting sites for birds, and berries as food for several species, it has been planted for wildlife management in parts of the United States.
In Europe, E. umbellata has spread to the United Kingdom, Belgium, France, and Italy, but has been cultivated in the Netherlands and Scotland. In some parts of North America where it has become naturalized, E. umbellata is considered a noxious weed, particularly in the central and northeastern United States. In Canada, it is a “prohibited noxious weed” under the Alberta Weed Control Act 2010.
Because it fixes atmospheric nitrogen in its roots, E. umbellata may grow vigorously and sometimes competitively in infertile soils. It can increase available nitrogen in soils and benefit some nearby plants, and when grown in orchards, it can increase yields of adjacent fruit trees up to 10%. However, its ability to change soil chemistry can severely alter or destroy native plant communities.
II. How to Grow and Care
Sunlight
Autumn olive shrub likes sufficient sunlight, but can also grow in slightly shady environments. It grows best in an open space with over 3 hours of sunlight daily. If light conditions are poor, it won’t grow healthily. Shade it from direct sunlight in hot summers to avoid withering from the blazing sun.
Temperature
plants of the Elaeagnus genus are distributed throughout temperate and subtropical zones. They like warm, moist environments and can tolerate temperatures down to -23 to 2 ℃. Mature autumn olive has strong heat-tolerant and drought-enduring capabilities and only needs watering in dry, hot summers.
Watering
In the first year after planting, autumn olive seedlings need sufficient water. Water infiltrates down in well-drained soil and helps the seedling roots develop downwards. Usually, watering once a week in the spring and summer can keep 30 cm-deep soil moist. Watering can stop in the fall when the seedling moves into dormancy. Mature autumn olive is drought-resistant and only needs watering in dry, hot summers.
Soil
Autumn olive shrub is highly adaptable to soil, and can survive and grow in various soil types. It grows as healthily in slightly acidic to alkaline soils, with the most proper pH value being between 6.0-7.5. It can adapt to drought and saline-alkali soil, but cannot tolerate waterlogging. The soil should have good drainage.
Fertilizing
Garden-planted autumn olive shrub doesn’t require much fertilizing. Excessive fertilizing may even make the plant vulnerable to pests and diseases. In the winter, apply a small amount of compost organic manure, or slow-release shrub plant food, as instructed. Nutrients are often scarce in a pot, so apply a thin layer of organic fertilizers once every other month in the spring and PK fertilizer once in the fall to potted autumn olive.
Planting Instructions
When planting in the garden, choose a sufficiently sun-lit, elevated spot. Before planting, clean the soil thoroughly and remove the bigger rocks from the soil. Autumn olive shrub likes soil with good water drainage. If the drainage capacity is poor, it may help to mix fine sand into the soil. The depth of the planting pit should be the same as the height, and twice as wide, as the root ball. The soil surface should be level with the root collar (the juncture of the plant’s trunk and root system). After planting, water sufficiently and cover the soil with 5 to 8 cm-thick organic mulch.
If autumn olive is to be planted in a pot, choose a big pot with good air permeability and drainage holes no less than 25 cm in diameter, so the root system has enough growing space. It may help to lay some bone meal on the bottom of the pot (don’t mix with soil) and mix 1/5 perlite in the soil to increase drainage. After planting, add a 1 cm-thick layer of peat soil on top of the soil surface to help the soil keep moist.
Pruning
Prune for shape in the spring and summer. Winter is the time to prune old, dried branches or trim poorly-growing plants to half of their original height, which helps promote the sprout of robust new branches the next spring. To prevent pests and diseases from invading the branch incisions through rainwater, don’t prune on rainy days. Autumn olive branches are thorny, so wear thick gloves during pruning.
Propagation
Autumn olive shrub can propagate via semi-ripe cuttings, which usually takes place in the summer. Water the plant the night before you select the branches, pick robust new branches the next morning, and cut off 20 cm of them with a pair of sterilized gardening scissors. If there are flower buds on the branches, remove them all. If cuttage is not scheduled for that day, the branches can be wrapped in a wet towel and kept in the refrigerator.
On the day of cuttage, trim the length of the branches to 12 to 15 cm. Make sure the incisions are inclined, flat, and smooth, and apply a little rooting powder to them. The leaves and buds on the lower half of the branches should all be removed, and cut each remaining leaf on the upper halves in half. Mix sterilized peat and perlite at 1:1 ratio and place in a pot. Insert the branches 5 to 7 cm deep into the pot and keep them 20 cm apart from each other. Place the pot away from direct light and wind, and put transparent plastic film over the branches. Keep the soil moist, not waterlogged, and transplant after roots sprout.
Transplanting
Transplanting autumn olive is best during the burgeoning warmth of early spring, as it promotes optimal root development. Choose a well-draining, sun-exposed location for this hardy perennial. If needed, provide support during transplant to ensure stability and encourage healthy growth.
III. Uses and Benefits
Autumn olive is prized by gardeners for its petite yet fragrant blooms and attractive silvery, mottled leaves. This small bush or tree is appropriate for use in hedging and borders as it is easily pruned and shaped.
Find Where to Buy the Best Autumn Olive (Elaeagnus umbellata)
[content-egg-block template=offers_logo_shipping cols_order=3,2,1,5,4 hide=badge visible=number border_color=info limit=8]