Growing American Linden from Seed

American Linden (Tilia americana) also commonly referred to as Basswood is a fast growing forest species of New York State.  American linden is an important timber producing tree as its tendency to self prune its lower limbs produces a straight-grained knot free lumber that has many uses.  The lumber is light fairly strong and easily worked without splintering or splitting.  The characteristics of the wood make it the wood of choice for woodcarving, woodturning and detailed wood parts.  

Linden grows across a large area of the eastern United States extending well into the South and Midwest. Linden makes up a small percentage of the canopy trees of many forest types in the northeast but is seldom found in high percentages or pure stands.  Linden develops best on deep moist well-drained fertile soils but can be found on a range of sites from dry gravelly uplands to heavy clay soils.

In New York state Linden trees flower in early June.   When Linden is in bloom you will be attracted to the tree as much by sound as by the fragrant blossoms. Swarms of bees and other insects drawn to the nectar of the blossoms will create a loud buzzing sound that is hard to ignore. 

The fruit of Linden is small hard round nut or kernel, about the size of a pea.  The fruit consists of a seed coat, a woody pericarp or seed covering enclosing the endosperm and a single embryo. The fruits hang in a cluster from the tips of young branches. Each fruit is attached to a long narrow bract, which acts as a sail and aids in wind dispersal of the seed. Seed is dispersed primarily by wind but is not carried very far from the parent plant because of the size and weight of the seed.  Seed is also dispersed by birds and small mammals.  Linden trees usually produce some seed every year but large seed crops are produced every two to three years.  The year (2006) being a very good seed crop year.

Not all seed collected from a tree will be viable and have the potential to germinate.  Often Linden seed will be infertile or be infested with a seed weevil that feeds on the endosperm of the seed.  This larval feeding destroys the embryo.  Pay close attention to the seed covering, a small hole in the seed covering is a good indication of weevil damage.  Unfertilized seed will look the same as fertilized seed but the pericarp will be hollow instead of containing an embryo. A float test in water can help separate out infertile seeds, which float from fertile seeds which should sink.

Linden seed typically will take two or more years for germination to begin and complete germination will be distributed over two to three and as many as 5 years.  Linden seed exhibits delayed germination because of several factors.  The outer seed coat is impermeable to water which is necessary for germination.  The hard pericarp prevents the embryo from expanding and the embryo itself exhibits dormancy that delays germination.

Early harvest of the seed before it turns brown is the most reliable method to shorten the time period to germination.  Collect the seed from the tree  just as the seed begins to change from green to yellow and immediately place the seed in a moist soil mix.  Placing the seed in a blender or food processor to remove the seed coat has also helped to speed up germination.

For anyone wanting to grow Linden there are three easy steps. First collect the seed when mature, place the seed in a moist potting mix to maintain seed moisture until planted and third plant the seed in the soil or seed beds, then wait 2 or more years for germination. As insurance against poor germination or infertile seed collect and sow a surplus of seed. 

American Linden seedlings will grow in full sun to partial shade.  Linden seedlings will establish in old fields with a mix of young shrubs and saplings to second growth woodland that has sufficient light and canopy openings.  The seedlings will require some shading during the early establishment years but will then tolerate full sun. Linden trees growing in the open are vigorous root sprouters and will often develop multiple stems.  In full sun Linden develops a broad rounded open canopy with heavy low branching.  When growing in a woodland setting Linden will race for the sunlight and develop a tall straight limb free trunk and canopy 70 to 80 ft high.

Growing Linden from seed is an easy process but requires a fair amount of patience.  It is not too late to get out in the woods and start collecting Linden seed or scout for next years crop of seed.

this page updated February 20, 2009