Common hackberry

Common hackberry: how do you recognise it?

Habit

Broad, rounded crown on a straight trunk; about 18 m tall and 15 m wide.

Leaves

Oval with a long point and an uneven base, 5–12 cm, toothed, rough above; dark green, yellow in autumn.

Flowers

Small greenish flowers in April–May; not showy.

Fruit

Round, purple-black drupes about 8 mm across; thin, sweet flesh; they hang on into winter.

Bark

Grey-brown with corky, warty ridges.

Flowering: April–May · Plants: March–April and October–December · Pruning: February

Why grow it?

• Very tough: tolerates wind, drought, temporarily wet soil, chalky soil and city air.
• Broad, rounded crown that gives plenty of shade in summer, similar to an elm.
• Fruits that hang on into winter and attract birds.
• Distinctive bark with corky ridges, a striking winter feature.
• Yellow autumn colour and little maintenance.

Common hackberry: where does it grow best?

• Sun or partial shade; it grows best in a bright spot.
• Almost any soil: sand, loam or clay, acid to chalky.
• Dry to wet; it tolerates drought and temporary waterlogging.
• Allow for a crown up to 15 m wide and plant at least 8–10 m from buildings and pipes.

Light

Sun and partial shade

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Dry to wet

Size

18 m tall, 15 m wide

Hardiness

Hardy (to -35 °C)

Goes well with

• Dogwood: Colourful stems in winter beneath the broad crown.
• Hazel: A native shrub that also tolerates wind and shade.
• Ornamental grasses: A light, swaying foreground under the crown.
• Elder: A tough shrub that also feeds birds.

Common hackberry: when and how to plant it?

Plant in March–April and October–December.

1. Plant in March–April or from October to December, when the soil is not frozen.
2. Dig a hole twice as wide as the root ball and just as deep.
3. Set the tree at the same depth as in its pot or at the nursery and backfill with the soil you dug out.
4. Add a stake and tie the trunk loosely with a tree tie; remove the stake after 2–3 years.
5. Water generously straight away and spread a 5–8 cm layer of wood chips or bark mulch around the base.

Care

Water

In the first two summers, water thoroughly every week in dry spells. Once established, the tree is very drought-tolerant.

Feeding

Usually unnecessary. On poor soil, apply a layer of compost in spring.

Mulching

A mulch keeps the soil moist and suppresses weeds, especially around young trees.

Staking

Tie a young tree to a stake for 2–3 years and check the tie every year.

Fruit

Fallen fruit can get sticky on a terrace or path; sweep it up in autumn or winter.

Tip: Use it where other trees struggle, such as windy, dry, wet or urban spots. Just give it plenty of room: it grows big.

Common hackberry: when to prune it?

Pruning months: February.

When: It needs little pruning; if needed, in winter, in February, when it is bare.

How:

• Remove dead, damaged and crossing branches.
• Cut small branches just outside the branch collar, never flush with the trunk.
• On a young tree, remove competing leaders and keep a single main leader.
• Also remove dense clusters of twigs (witches’ brooms) by cutting the affected branches back into healthy wood.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Sow the seed outdoors in autumn in a tray of light soil, or after cold stratification in spring. It may lie dormant for a year before germinating.

Nursery

Seedlings grow slowly at first. For a handsome tree quickly, buy a young tree from a nursery.

Common hackberry: how does it get through the winter?

Hardy to −35 °C.

• Fully hardy, to about −35 °C: no protection is needed in Belgium.
• The corky bark and the fruits that stay on give the tree interest in winter too.
• In a hard winter, give young trees an extra layer of mulch around the base.

Diseases and pests

• Witches’ broom: Dense clusters of thin twigs in the crown. Usually harmless; prune them out if you wish.
• Leaf galls: Small bumps or growths on the leaves. Only a cosmetic flaw that needs no treatment.
• Aphids and honeydew: Sticky leaves and sooty mould in summer. Ladybirds and tits usually clear them up.
• Powdery mildew: White powder on the leaves, mostly at the end of summer. Usually harmless.

Through the year

• February: Prune if needed. Remove dead branches and witches’ brooms.
• March: Plant. Apply mulch.
• April: Plant. The small flowers open.
• May: Leaves fully out. Water young trees in dry weather.
• June: Water young trees in dry weather.
• July: Water young trees during prolonged drought.
• September: Fruit begins to colour.
• October: Yellow autumn colour. Plant.
• November: Plant. Leave the leaves as mulch.
• December: Rest. The fruits stay on for the birds.

Good for wildlife

Birds

Berries, seeds or insects as food, or a place to nest.

Did you know?

• After Dutch elm disease, the tree was widely planted in North America as a replacement for elm.
• The fruits often hang on the tree into winter.
• The tree used to belong to the elm family but is now classed in the hemp family.