How to Grow and Care for Basswood Tree

Basswood, also commonly called a linden or lime, is an ornamental shade tree with a large canopy that creates deep shade and branches covered in densely bright green leaves with an asymmetrical heart shape. Basswood grows best in seasonably moist but well-drained soil conditions, does well in slightly acidic soil, requires full or partial sun, and the tree is not considered to be very drought tolerant.

Basswood Care

Here are the main care requirements for growing a hardy, easy-maintenance basswood tree:

• Choose a site that will accommodate this very large tree.
• Plant in full sun for best results, but the tree will tolerate some shade.
• Check the alkalinity in your soil to see if your type of basswood can tolerate the level well.
• Water well in the first two years until the tree is established.
  

Light

You will find that most basswoods prefer full sun and will produce the most blossoms under this condition. Some species have a slight tolerance for partial shade, but you will notice a distinct reduction in flowers when enough light is not present.

Soil

The soil conditions for various Tilia species will mostly hover around the average to the moist range, ensuring that the soil is well-drained. Throughout the genus, the pH scale will vary from species to species, with some being more inclined to tolerate higher alkalinity, like the Tilia cordata, the small-leaved linden. By contrast, American basswood (Tilia americana) will not tolerate highly alkaline soils.

Water

One of the wonderful things about planting native trees is that they will usually not require supplemental irrigation once they are planted and established in their native areas.

Basswoods are not drought tolerant, so if you live in an area prone to drought, you may need to do some supplemental watering in dry conditions. Water the tree well until it is established, following the standard rule of 10 gallons per week per inch of trunk diameter. Continue watering like this for the first two years.

Temperature and Humidity

There are around 30 species of Tilia from around the globe, with most able to hybridize with the others. The species can vary in their tolerance for temperature and humidity, and it is best when looking to design your landscape you do some research to see what basswood tree is the best fit for your hardiness zone.

Fertilizer

Most trees not bred in cultivation will do just fine without supplemental fertilization. But if you apply a slow-release granular fertilizer in the fall and you'll notice a difference in the basswood. A general-purpose tree or flowering tree fertilizer should do the trick. You are looking for healthy foliage and bloom production, so a higher N and P number is best in the NPK formulation.

Types of Basswood

• Little-leaf linden (Tilia cordata): This type of basswood grows in USDA zones 3 to 7, though it's native to Europe. It grows 60 to 70 feet tall, and 40 to 50 feet wide.
• American linden (Tilia americana): Native to the eastern United States, the American linden grows up 50 to 80 feet tall, and 40 to 60 feet wide. It grows best in zones 2 to 8.
• Silver linden (Tilia tomentosa): The silver linden, native to the area that ranges from southeast Europe to Turkey, grows in USDA zones 4-7. It can grow 50 to 70 feet tall, and 40 to 50 feet wide.
• Henry's lime (Tilia henryana): Native to Eastern China, Henry's lime grows best in zones 6 to 8 where it can grow 70 to 80 feet tall and 50 to 60 feet wide.

Pruning

When it comes to pruning, you should prune basswood to the desired form while it is still young. Mature basswood trees do not tolerate pruning well.

Propagating Basswood

The best way to propagate basswood is from a cutting. Though you can harvest and plant basswood tree seeds, it is not recommended due to the lengthy wait for seeds to form on the tree and then to germinate. There is also a very low success rate of germination with basswood tree seeds.

To propagate a basswood tree with a cutting, wait until you can find a softwood cutting in May, June, or July. A softwood cutting is identified as a young, flexible shoot branch tip, which is easier to root. Take the following steps:

1. Find a shoot branch with a few newer leaves that can be snapped somewhat easily when bent. Using a sterile cutting tool, take a 6- to 8-inch long cutting from the branch.
2. Remove the leaves from the shoot except for the pair at the top of the cutting.
3. Carefully slice two vertical lines on the base of the cutting. Dip the cutting into rooting hormone to help it root.
4. Plant the cutting into a sandy bed of soil or in a gallon pot with numerous drainage holes.
5. Keep the soil around the cutting moist.
6. Roots should form around six weeks.
7. Plant the seedling in its permanent spot in the early fall or keep it in the pot in a protected area until the spring when you can plant it in the ground.
   

Common Pests & Plant Diseases

The two common pests that infest basswood trees are likely scale and walking stick bugs, making them hard to spot. A large infestation of scale will engulf branches that need to be pruned and treated with horticultural oil to suffocate any remaining eggs on the rest of the tree. A common, small infestation of walking sticks won't do much damage though a rare, large infestation will noticeably defoliate leaves.

Look for diseases that can affect basswood trees. Proper pruning and good air circulation in and around the tree are critical factors in limiting diseases. Common basswood tree diseases include the following:

• Blight: This fungal infection occurs when spores from diseased soil or shoots splash onto new growth, especially in crowded areas of growth.
• Verticillium wilt: A fungus also found in the soil, the disease travels through a tree's vascular system.
• Powdery mildew: This disease occurs in humid conditions and shady areas in growth that have little air circulation.
• Anthracnose: Symptoms on leaves are not attractive, but this fungal disease of the foliage will rarely kill the tree.
• Canker: Cytospora canker is another fungal infection that affects mature trees and travels through wounds in the tree and causes cankers on the branches, resulting in branch dieback. Affected branches need to be pruned in dry weather.

How to Get Basswood to Bloom

Bloom Months

A basswood tree will blossom from June through August.

What Do Basswood Flowers Look and Smell Like?

Hanging, branching clusters of basswood flowers are smallish, airy, and not very showy—each bloom has a layer of petals and sepals and numerous stamen. The flowers on a basswood are designed for pollinators. The sweet-smelling white or pale yellow flowers attract honeybees for the pollen and nectar, though different types of basswood trees may produce varying amounts of nectar.

How to Encourage More Blooms

Some types of basswood trees will bloom better in full sun while others bloom fine in some shade. In general, keep the tree healthy and clear of debris to encourage more blooms in sun or shade. Do not mulch heavily and do so away from the base of the tree. Cut any suckers away that appear at the base of the tree.

Common Problems With Basswood

For the most part, the basswood tree is exceptionally hardy and easy to care for. It will not take a lot of planning or much care other than accounting for the tree's large size, sticky excretions, and fungal diseases. Look for the following signs of problems that need attention:

Sticky Excretions

The basswood tree attracts insects that love its sweet delicious sap, and these insects sometimes secrete a sugar-based fluid, excreted by certain plant-sucking insects, called honeydew. This secretion can cause a mess on your property and be a nuisance and unsightly, and if left on cars, it can damage finishes. Avoid this situation by either placing new trees away from parked cars and other structures or discouraging parking or placing outdoor furniture long-term under an established tree.

Spots on Leaves

Spots on leaves indicate any number of fungal issues. Anthracnose appears on the underside of leaves as small circular tan, dark brown, or black blotchy spots on new growth that cause leaf drop. Clean up and destroy fallen leaves, prune, and use a fungicide if absolutely necessary. Irregular black or brown spots on the leaves of younger trees can also indicate blight. Pruning affected areas and making sure there is adequate air circulation in and around the tree will be the best way to control blight.

Wilting

A basswood tree with wilting, yellowing, or drying leaves, especially at the top of the crown and upper branches, may have verticillium wilt. It's a deadly and incurable disease but to mitigate it, water and fertilize the tree regularly when it's dry and prune off affected branches with disinfected cutting tools.