Lindens are neat, naturally pyramidal shade trees, and many popular cultivars are bred for a strong central trunk. That means pruning a linden is mostly about keeping a good structure going while the tree is young, and doing very little once it is mature.

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The short answer: prune lindens in late winter, before buds break; Colorado State University Extension says this is when wounds close fastest and branch structure is easiest to see. Midsummer also works. Avoid the spring growth flush and major cuts from early fall to midwinter. Remove dead, broken, crossing and rubbing branches, keep a single central leader, remove codominant stems early, and keep cuts under 2 inches where possible. Never remove more than 25% of a healthy tree’s foliage in a year, and much less on a mature tree.

Know your linden

The Morton Arboretum describes little-leaved linden (Tilia cordata) as a 60- to 70-foot tree with an oval to pyramidal, upright form. Several cultivars are selected for structure:

Cultivar	Size and form (Morton Arboretum)
‘Greenspire’	About 50 ft; neat pyramidal shape with a central leader
Corinthian (‘Corzam’)	About 45 ft tall and 15 ft wide; narrow pyramid with a straight central trunk and evenly spaced branches
‘Chancellor’	About 50 ft; upright when young, more pyramidal with age
Shamrock (‘Baileyi’)	About 50 ft tall and 30 ft wide; more open crown
Summer Sprite (‘Halka’)	About 20 ft tall and 15 ft wide; compact and rounded

A cultivar that already grows with a central leader needs less corrective pruning. Your job is mostly to keep competing leaders from developing.

When to prune a linden

Colorado State University (CSU) Extension gives clear timing for structural pruning of shade trees:

Late winter, before trees break dormancy, is the main pruning window. Wounds close faster, the tree has stored energy, and you can see the branch structure before leaves hide it.
Midsummer is also a good time.
Avoid the spring growth flush, when bark tissues separate easily.
Avoid major pruning from early fall to midwinter, because of the risk of frost cracks and because dormant trees cannot respond actively to pruning.
Minor pruning, meaning branches 2 inches or less and less than 10% of foliage, can be done any time.

The International Society of Arboriculture (ISA) agrees that light pruning of dead or weak limbs can be done any time, and that growth and wound closure are best when pruning takes place before the spring growth flush.

Step 1: clean out problems

Start with branches that are dead, damaged, diseased, crossing or rubbing. CSU lists removing these as the first structural pruning objective, and the ISA describes cleaning as the removal of dead, dying, diseased, weakly attached and low-vigor branches.

Step 2: keep one central leader

CSU says trees are less likely to fail if they have a single dominant leader, and it calls codominant trunks (two or more upright leaders of near equal size) a major structural defect. Their unions do not develop a branch collar and often have included bark, where bark is pressed against bark instead of being joined by sound wood. If your young linden has two competing tops, choose the straighter, stronger one and remove or shorten the other while it is small.

Step 3: space the main branches

CSU recommends choosing well-spaced permanent (scaffold) branches and keeping them less than half the diameter of the trunk, so they form a strong branch collar. Its guide suggests spacing scaffold branches by at least 3% of the tree’s expected mature height. For a 60-foot linden, that is roughly 22 inches apart vertically. Temporary branches, such as low limbs below the permanent crown, should be removed before they reach 2 inches in diameter.

CSU also recommends keeping the live crown, the part of the tree covered in branches, at 60% or more of the tree’s height. Do not strip off lower branches all at once.

Step 4: make good cuts

CSU says pruning cuts should be 2 inches in diameter or smaller where possible; cuts over 4 inches should only be made when there is no other option, because large cuts increase the potential for decay.
Cut just outside the branch collar, the slightly swollen ring where a branch joins its parent.
Never top a linden. The ISA calls topping perhaps the most harmful tree pruning practice known, leading to stress, decay and risk.

How much to remove

CSU cites ANSI standards: no more than 25% of a healthy tree’s foliage should be removed in a year. It advises no more than 10% for mature trees, while young trees can tolerate more. Until a newly planted tree is established, limit pruning to dead and broken branches and major structural defects. Trees under drought stress should not be pruned.

Pruning a mature linden

Mature lindens need little routine work beyond removing dead or broken limbs and, if needed, raising low branches over walks. The University of Illinois Extension notes littleleaf linden produces few root sprouts. Large limbs, and any work that needs a ladder or a saw overhead, are a job for a certified arborist.

After pruning

The Morton Arboretum recommends a mulch layer to keep a linden’s roots cool. It also notes aphids and Japanese beetles can be problems, and Illinois Extension says Japanese beetles can be very damaging. Pruning does not fix these, so check the leaves in summer.

Sources

Structural Pruning of Young Shade Trees (GardenNotes), Colorado State University Extension
Pruning Your Trees, International Society of Arboriculture, TreesAreGood.org
Little-leaved Linden, The Morton Arboretum
Littleleaf Linden (Selecting Trees for Your Home), University of Illinois Extension

Top photo: Asurnipal, CC BY-SA 4.0, via Wikimedia Commons

How to Prune Linden Trees