Tree · Malvaceae
American Basswood
Tilia americana
A big, easygoing shade tree with fragrant summer flowers the bees can't resist.
Full sun
Every 7–14 days
USDA 3–8
60–80 ft · 18.3–24.4 m
Overview
American basswood, better known as linden, is a tall native shade tree that earns its other nickname, the bee tree. In late spring and early summer it covers itself in small, pale-yellow flowers whose scent carries on the air, and pollinators work it from dawn to dusk. Left to grow, it reaches a commanding 60 to 80 feet (18 to 24 m) with a broad, rounded crown.
This is a tree for the long haul and a forgiving one. It's hardy through cold winters, takes full sun or part shade, and isn't fussy about soil as long as it drains. The big heart-shaped leaves cast deep shade, and the soft, light wood gave basswood its name and its old reputation among carvers.
Plant it where it has room to spread and you won't have to fuss over it. The main thing to know is that aphids love it, dripping sticky honeydew in summer, so it's worth keeping that in mind before you set a patio or a parked car beneath the canopy.
Care
The short version: full sun to part shade, in moist, well-drained soil, with steady water while it's young and little else once it settles in.
Light
Linden grows best in full sun but takes partial shade in stride. More sun means a denser crown and heavier bloom, while a shadier spot still produces a perfectly healthy, if looser, tree.
Water
Keep a young tree evenly moist, watering every 7 to 14 days through dry stretches. Once it's established it shrugs off some drought, but it always does better with steady moisture, so don't let it bake for weeks on end.
Soil
It isn't picky and handles clay, loam, or sand, as long as the ground is medium-moisture and well-drained. A pH anywhere from 5.5 to 8.0 suits it, which covers most garden soils you're likely to have.
Temperature
This is a cold-hardy tree, comfortable from -40°F to 100°F (-40°C to 38°C). It handles harsh winters and hot summers alike, which is why it thrives across so much of the country.
Humidity
Outdoor humidity is never an issue for a linden, so there's no number to hit. Air circulation matters more, since still, damp air around the canopy is what invites leaf spots and mites.
Feeding
An established tree in decent soil rarely needs feeding at all. If growth is weak, work in a balanced slow-release tree fertilizer in early spring, but go light, since too much nitrogen only feeds the aphids.
Pruning
Prune in late winter to early spring to build one strong central leader and to cut out dead, damaged, or crossing branches. The tree also throws up basal suckers and sprouts, so pull those off whenever they appear.
Repotting
Linden is a landscape tree, not a container plant, so repotting doesn't apply once it's in the ground. If a nursery tree shows roots circling the pot or running out the drainage holes, get it planted out without delay.
Size & spacing
Give a linden real room, because it climbs to 60 to 80 feet (18 to 24 m) tall and spreads 30 to 60 feet (9 to 18 m) across. Site it well clear of buildings, walls, and overhead lines so the wide crown can fill out.
When to plant
Linden is a tree, so there's no annual sowing season to track. Set young trees out in spring or fall, after the hard frosts have passed, and the fragrant flowers follow on their own from late spring into midsummer.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring or fall, after the threat of hard frost has passed
- Harvest: Fragrant pale-yellow flowers in late spring to early summer (May to July)
Hardiness
USDA hardiness zones: 3–8
Temperature: down to -40°C
Troubleshooting
A healthy linden mostly takes care of itself, and most of what you'll notice is cosmetic. Match the signs below before you reach for any treatment, since a large tree usually shrugs off pests that would worry a smaller plant.
Wilting limbs with sawdust and round holes in the trunk
The linden borer tunnels through the wood of the lower trunk and limbs, and you'll spot round exit holes and sawdust-like frass where it works. Prune out and destroy any infested limbs. Borers go after stressed trees first, so keep yours watered and avoid nicking the bark with mowers and trimmers; call an arborist if the trunk itself is hit.
Fix:
- Prune out and destroy borer-infested limbs
- Keep the tree vigorous, as borers preferentially attack stressed trees
- Consult an extension office or arborist for severe trunk infestations
Sticky leaves with a black film, and gummy ground below
This is aphid honeydew, and the black is harmless sooty mold growing on the sugary residue. Heavy aphid colonies, sometimes joined by scale insects, drip the sticky coating onto everything underneath. Blast the bugs off with a strong jet of water, let lady beetles and lacewings do their part, and the mold fades once the honeydew stops.
Fix:
- Hose aphids off with a strong jet of water
- Encourage beneficial predators such as lady beetles and lacewings
- Apply insecticidal soap or horticultural oil to accessible foliage for severe infestations
- Sooty mold disappears on its own once the honeydew source is controlled
Summer leaves chewed down to a lacy skeleton
Japanese beetles strip the soft tissue between the veins and leave the canopy looking like lacework from June to August. On a young tree, knock the metallic green beetles into soapy water early in the morning. A big established linden shrugs off the damage and leafs out fine, so skip the pheromone traps that only lure in more.
Fix:
- Hand-pick or knock beetles into soapy water in the early morning on smaller trees
- Tolerate damage on large established trees, which recover
- Avoid Japanese beetle pheromone traps, which attract more beetles
Stippled, spotted, or browning leaves
Several culprits leave the foliage looking off. Lace bugs, basswood thrips, or spider mites stipple the leaves and leave dark fecal specks on the undersides, while fungal leaf spots show up as distinct lesions in wet seasons. Rake up fallen leaves to cut down on spores, hose the canopy in dry spells to knock back mites, and otherwise leave it be, since most of this is cosmetic.
Fix:
- Rake and dispose of fallen leaves to reduce fungal spores
- Hose down foliage to dislodge mites in dry spells
- Most leaf spot is cosmetic and needs no treatment
Toxicity
Good news for pet owners: linden is completely safe. The ASPCA lists it as non-toxic to cats, dogs, and horses, and it carries no poisonous compounds anywhere in the tree. The fragrant flowers are even dried for a calming tea, and the young leaves are tender enough to eat.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The ASPCA lists linden as non-toxic to cats, so a curious nibble is nothing to worry about. As with any plant, a big mouthful might bring on a little stomach upset, but the tree carries no poison.
Dogs None
Dogs are in the clear here too, with no toxic principles in the leaves, bark, or flowers. A dog that gnaws on a fallen branch should be fine.
Horses None
Horses can browse a linden without harm, and the species is on the ASPCA non-toxic list for them. The young leaves and flowers are safe forage.
Rabbits Safe
Rabbits can chew the leaves and twigs with no toxic risk. Linden is a common browse plant, and the tender spring growth is perfectly safe for them.
Livestock Safe
Cattle, goats, and sheep can graze the foliage safely, and the tree holds no compounds that trouble them. Linden has long been cut for fodder without issue.
Birds Safe
Birds nest in the canopy and feed around the flowers without any danger. The seeds and buds pose no toxic threat.
People Safe
Linden is safe for people, and the fragrant flowers are dried for a soothing tea while the young leaves are tender enough to eat. There are no toxic parts to avoid.
No special handling precautions; honeydew from aphids can make surfaces under the tree sticky but is not toxic.
Varieties
Lindens come in a few forms worth knowing, from compact native selections to silver-leaved cousins. These are the ones you'll meet most often in yards and along streets.
Tilia americana 'Redmond'
A tighter, more pyramidal selection of the native tree that tops out around 40 to 60 feet, which makes it a favorite for formal shade and street planting.
Tilia cordata 'Greenspire'
A littleleaf linden with small heart-shaped leaves of 1 to 3 inches and a dense oval crown, prized as a tough, city-proof street tree across Europe and beyond.
Tilia tomentosa
The silver linden, whose dark green leaves flash their white woolly undersides whenever the wind turns them, so the whole tree shimmers.
How to propagate
Linden is propagated a few different ways depending on what you're after, from slow seed to grafting for named cultivars to the suckers the tree offers up freely.
SeedDemanding
Sow cleaned seed outdoors in fall, or stratify for sowing in spring · 1-2 years or more to germinate
Growing linden from seed is a test of patience. The seeds carry a hard coat and double dormancy, so even with warm-then-cold stratification they can sit for one to two years before sprouting, and they come up slow and uneven. Sow cleaned seed outdoors in fall, or stratify it for a spring sowing, and don't expect quick results.
GraftingDemanding
Late winter for bench grafting or summer for budding · 1 growing season to take
Named cultivars like 'Redmond' and 'Greenspire' won't come true from seed, so growers graft or bud them onto seedling rootstock instead. Bench graft in late winter or bud in summer, and a successful union takes hold over a single growing season.
LayeringModerate
Spring · 1-2 years to root
Basswood throws up sprouts and suckers from its base on its own, which gives you an easy clone to work with. In spring, pin a low branch to the ground to layer it, or lift a rooted sucker, and give it one to two years to build its own root system before moving it.
Myths
Linden trees are poisonous to dogs and cats.
The ASPCA lists linden as non-toxic to dogs, cats, and horses, with no toxic principles in any part of the tree. A pet that gulps down a lot of any plant might get a mild stomachache, but there is nothing poisonous about a linden.
The sticky black coating on basswood leaves is a disease that's killing the tree.
The sticky film is just aphid honeydew, and the black is harmless sooty mold feeding on the sugars. It looks alarming but it's purely cosmetic, and it clears on its own once the aphids are dealt with. An established tree is never harmed by it.