American basswood

American basswood: how do you recognise it?

Habit

Large deciduous tree, 20–25 m tall and 12–15 m wide, with a straight trunk and a broad, rounded crown.

Leaves

Heart-shaped and lopsided at the base, 10–20 cm, coarsely toothed; dark green above, paler beneath. Yellow autumn colour.

Flowers

Small clusters of scented, creamy-yellow flowers hanging from a long, pale bract, in June–July.

Fruit

Small, round, downy nutlets hanging from the bract that the wind carries away.

Bark

Grey-brown with long furrows; fairly smooth on young trees.

Flowering: June–July · Harvest and fruit: April–July · Plants: March–April and October–December · Pruning: December–February

Why grow it?

• Scented flowers in June–July that attract plenty of bees and bumblebees.
• The big leaves cast deep shade in summer and give a lush effect.
• Lovely yellow autumn colour before the leaves fall.
• Fully hardy and tough: an impressive specimen or avenue tree.
• The long, pale bract on the flower and fruit clusters is an attractive detail.

American basswood: where does it grow best?

• Sun to partial shade; it grows and flowers best in sun.
• Deep, humus-rich, moisture-retentive soil: sand, loam or clay, acid to chalky. It dislikes long droughts and compacted, waterlogged ground.
• Normally moist soil; water young trees in dry summers.
• Allow for a spread of 12–15 m and keep at least 10 m away from buildings, pipes and paving.
• Preferably sheltered from hot, dry wind, which scorches the edges of the big leaves.

Light

Sun and partial shade

Soil type

Sand, loam or clay

Acidity

Not fussy

Moisture

Normal

Size

25 m tall, 15 m wide

Hardiness

Hardy (to -35 °C)

Goes well with

• Snowdrop: Flowers in February–March, before the basswood is in leaf.
• Wood anemone: A spring plant that thrives in the partial shade beneath the tree.
• Lesser periwinkle: Evergreen ground cover for under the crown.
• Hornbeam: A sturdy companion in a tree group or hedge.

American basswood: 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 neither frozen nor soaking wet.
2. Dig a hole at least twice as wide as the root ball but no deeper, and loosen the sides so the roots can spread easily.
3. Set the tree at the same depth as in the nursery or container and backfill with the excavated soil, mixed with a little compost if you like.
4. Put in a sturdy stake on the windward side and tie the trunk loosely with a tree tie. Remove it after 2–3 years.
5. Water in with 20–30 litres straight away and spread a 5–8 cm layer of wood chips or leaf compost around the base, keeping it clear of the trunk.

Care

Water

For the first 2–3 years give a thorough 20–30 litres every week in dry spells. An established tree usually copes, but appreciates water in a long drought.

Feeding

Usually not needed in good soil. In poor soil spread a layer of compost under the crown in spring.

Mulching

A ring of wood chips or compost keeps the soil moist and the grass back; keep the trunk itself clear.

Suckers

Shoots may appear around the base. Dig or cut them out as soon as you see them.

Trunk protection

Protect the young trunk with a guard against mowers, rabbits and deer.

Tip: Do not plant it above a terrace, drive or parking space: in summer sticky honeydew drips from the crown. Give it an open spot where it can reach its full spread.

American basswood: when to prune it?

Pruning months: December–February.

When: Prune during dormancy, from December to February, on a dry, frost-free day. A well-shaped tree needs little pruning.

How:

• In the first years train a straight trunk with a single leader and remove competing leaders.
• Take out dead, crossing and damaged branches; cut just outside the branch collar, leaving no stubs.
• Remove low branches gradually if you want a taller clear trunk.
• Suckers and water shoots at the base can be cut away at any time of year.

Caution: Have major pruning of a mature tree done by a qualified arborist, and never prune during flowering in June–July.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

The seed needs a long winter rest. Collect the nutlets in autumn, sow them outdoors and be patient: germination can take a year or two.

Grafting

Selected forms are grafted onto a rootstock by nurseries. This is not a job for home gardeners.

American basswood: how does it get through the winter?

Hardy to −35 °C.

• Fully hardy, to about −35 °C: no protection is needed in Belgium.
• Protect young trees in their first winters with a guard against rabbits and deer.
• It is far too big for a pot and belongs in open ground.

Diseases and pests

• Aphids and honeydew: In summer, sticky drops on leaves, cars and patio tables, later with black sooty mould. Do not plant the tree above a terrace or parking space. Ladybirds and hoverflies help keep aphids down.
• Leaf scorch: Brown, dry leaf edges after hot, dry, windy summers. Water young trees in drought and mulch the soil.
• Mite galls: Small red or green bumps on the upper side of the leaves. They look odd but do the tree no harm; no action is needed.
• Basal suckers: Shoots at the base drain the tree’s energy. Simply remove them.

Through the year

• January: Prune on a frost-free day. Check stakes and ties.
• February: Last chance to prune before spring.
• March: Planting is possible again. Apply mulch.
• April: Plant until mid April. Water new trees in dry weather.
• May: Leaves unfold. Remove suckers at the base.
• June: Flowering begins: scented blossom. Water in dry spells.
• July: Full flower with plenty of bees. Water young trees.
• August: In drought, water young trees thoroughly every week.
• September: Fruits ripen. Collect seed if you wish.
• October: Yellow autumn colour. Planting is possible again.
• November: Leaf fall. Plant until December.
• December: Plant in open weather. Start winter pruning.

Edible and useful

Blossom (June–July)

Pick the blossom together with its pale bract on a dry day, when most of the flowers have just opened and smell strongly: in June for large-leaved lime, from late June to mid-July for small-leaved lime. For tea, cordial or a fragrant bath. Leave plenty for the bees.

Leaves (April–May)

The young, soft leaves of April and May can be eaten raw; they taste mild and slightly mucilaginous, and are good in a salad or a sandwich.

Storing

Dry the blossom in a thin layer on a rack or in a paper bag, somewhere airy and out of the sun, until it rustles. Keep it in a tightly closed jar in the dark for up to a year. Old, browned blossom has lost its scent.

Caution: Do not pick from trees along busy streets or from trees sprayed against aphids. Throw away blossom that smells musty or has gone mouldy. Do not pick more than you need: lime trees are an important food source for bees. Never eat anything you have not identified with certainty.

Eating and using is at your own risk: see the terms of use.

Recipes

• Lime-blossom tea (Tea · 1 cup · 10 min)
• Lime-blossom cordial (Syrup · ± 1 litre · 30 min + 24 hrs steeping)
• Lime-blossom bath (Skin and body care · 1 bath · 20 min)
• Lime-flower and apple jelly (Jelly · ± 4 jars of 250 ml · 45 min + 12 hrs steeping)
• Stuffed lime leaves with rice (Dish · 4 portions (± 20 rolls) · 1 hr 15)

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• The name basswood comes from ‘bast’: the fibrous inner bark was used to make rope and mats.
• The wood is soft, light and even-grained, which makes it a favourite with wood carvers.
• In North America basswood honey is a well-known, light honey.