American linden, is a hardy shade tree with a broadened columnar form, heart-shaped leaves, and small, greenish springtime flowers that are very fragrant. These flowers often attract many pollinating insects, including bees. If pollinated, the flowers give way to small, rounded, hairy fruits that often stay on the tree into winter. The bark is smooth and brown when young, but becomes lightly furrowed and grayish with age. The autumn foliage of the American linden is rarely spectacular.
- Common name: Basswood; linden
- Botanical name: Tilia americana
- Zones: 3 to 8
- Size: To 100 feet tall, 50 feet wide
- From: areas of North America
- Family: Tiliaceae (linden family)
- Sun: Full sun is best; they will tolerate partial shade.
- Soil: Ensure the soil retains moisture, but still drains well. The plant prefers a soil rich in organic matter-add organic matter to the area before planting. It tolerates sandy soils, but doesn't grow in heavily compacted soils or heavy clays.
- Moisture: Water in times of drought.
- Mulch: A 2- to 3-inch-deep layer of mulch over the soil around the tree helps conserve moisture, reduces competition from weeds or turf grass, and protects the tree's bark from damage from lawn mowers or string trimmers. Leave a 4-inch gap between the mulch and the tree's trunk.
- Pruning: Prune lindens either in midsummer or mid-winter. Because of the sap flow, avoid pruning in spring, autumn, or late winter.
- Fertilizer: In most soils, fertilizing is unnecessary. Use a balanced fertilizer in spring if necessary.
- Seed: Plant linden seeds in outdoors in late autumn or early winter, once the fruits have ripened and fallen from the tree. Plant them in a sheltered spot in the garden or in a cold frame. These seeds generally do not do well when started indoors as they need several months of cold temperatures to break dormancy.
- Anthracnose: If the leaves look scorched and spotted, the cause may be anthracnose. The spots may be gray, tan, or dark brown; dry or slimy. To deter the disease, prune off any infected branches, dipping your pruning tool in a bleach or alcohol solution between cuts. Prune some of the inner branches to keep good airflow in the tree's center.
- Aphids: These small insects often appear in large numbers on new growth. Spray them off daily with a stream of water; they will not attack a plant after being knocked off. Use an insecticidal soap or neem-oil-based spray if infestations are severe.
- Borers: These insects bore tunnels beneath the bark. You might see small holes with sawdust beneath them. To deter borers, encourage beneficial insects and use horticultural oil while the trees are dormant.
- Canker: Forms dark water-soaked cankers on the bark and branches of the tree. The cankers can spread, becoming larger. To deter the disease, prune off any infected branches, dipping your pruning tool in a bleach or alcohol solution between cuts.
- Japanese Beetles: These beetles are darkly colored and chew holes in plant leaves. Hand-pick the beetles from the plants and drop the insects in a bucket of soapy water. You might also try spraying with a pesticide made from neem, a tropical tree. Finally, apply a bacterium to your soil called Milky Spore. This bacterium attacks the grubs from the beetles, but can take a couple of years to control the beetles.
- Leaf spot: In summer or autumn, the leaves become spotted yellowish or with darker colored spots. Each spot often has concentric rings around it, forming something of a bull's-eye pattern. To deter it, prune the plant to keep good air flow and avoid wetting the foliage in afternoons and evenings.
- Powdery mildew: This disease tends to appear in mid- to late summer and looks like someone dusted affected leaves with a grayish powdery covering. The leaves then drop off. To deter the disease, prune the plant to keep good air flow and avoid wetting the foliage in afternoons and evenings.
- Lindens are sensitive to pollution and rarely truly thrive in especially urban settings.
- Lindens tend to have somewhat shallow root systems.
- Tilia americana 'Boulevard' grows to about 60 feet tall, 30 feet wide, and has a pyramidal habit. Yellow autumn foliage.
- Tilia americana ' 'Fastigiata' grows to about 70 feet and has a more cone-shaped habit.
- Tilia americana ' ‘Macrophylla' grows to about 50 feet and bears larger leaves than the species.
- Tilia americana ' ‘Pyramidalis' grows to about 50 feet and has something of a pyramidal habit.
- Tilia americana '‘Redmond' grows to about 50 feet and bears a denser habit than the species.