Bald Cypress in a Residential Yard: Knees, Roots and Room

Bald cypress is the tree standing in the water along the St Johns and in the low spots around Osteen and DeBary, and it is one of the best trees we have. It handles flooding, it handles drought once established, it rides out hurricanes better than nearly anything, and it lives for centuries.

It is also a large tree with a habit that catches people off guard when it is planted in a subdivision lot. This is what you are signing up for, and how to manage one you already have.

Why bald cypress holds up in storms

Cypress is a conifer, but not a brittle one like pine. The wood is flexible, the crown is narrow and conical in youth, and the root system is wide and deep where the soil allows. In a hurricane, cypress bends and loses foliage rather than snapping or uprooting. In our post on which trees fail first in a Florida hurricane, cypress lands firmly in the group that holds.

It also drops its needles in late fall, which is where "bald" comes from. Homeowners new to Florida sometimes call in October convinced the tree is dying. It is not. It will flush again in spring.

The knees

Cypress knees are the woody projections that come up from the roots, sometimes a few inches high, sometimes a couple of feet. They are most common on wet sites and on trees that are well established. Nobody has settled exactly what they are for, but the practical question is what to do about them in a lawn.

You can cut knees off. Trimming them flush to the ground with a saw does not harm the tree, and it is the standard way to keep a lawn mowable. They may come back. What you should not do is dig into the root system trying to remove them at the source, because that damages structural roots for no benefit.

If a cypress is planted in a consistently wet part of the yard, expect knees. If it is on a drier, well-drained site, you may see few or none.

Roots and hard surfaces

Cypress roots are wide and, on high-water-table sites, shallow. They will lift a sidewalk or driveway placed too close, the same way an oak will. The difference is that cypress roots are more tolerant of being cut when it is done properly, which gives you more options when a root is in the way of something. Read Roots Lifting Your Driveway? before anyone cuts anything.

Planting distance matters. A bald cypress will get tall and the trunk will flare wide at the base. Give it real room from the house and from paving, and it will be the least troublesome large tree on the lot.

Pruning a cypress

Very little. Cypress develops a strong central leader on its own and rarely forms the codominant stems that make oaks a structural project. The work it needs is:

• Deadwood removal as the lower limbs shade out and die
• Clearance over the roof, driveway or walk
• Removal of any limbs broken in a storm, cut back to the collar

Do not top a cypress. It does not develop a nice rounded crown when topped; it develops a flat, ugly one with a cluster of weak leaders. Our tree trimming work on cypress is almost always deadwood and clearance.

Problems that do come up

Cypress is not immune to everything. Things we see on residential trees:

• Bagworms in some years, which look like small hanging cones made of needles. Usually cosmetic on a large tree.
• Chlorosis (yellowing) on high-pH sites, particularly near new concrete. Cypress likes acidic soil.
• Decline from grade changes. Burying the root flare under fill during construction will slowly kill a cypress just as it does an oak.
• Damage from mowers and trimmers to the root flare and knees, which opens the tree to decay.

Removing a bald cypress

Occasionally one has to come out, usually because it was planted a few feet from a foundation forty years ago. A mature cypress is a tall, heavy tree, and removal is a rigging job. The wood is prized, so ask whether the logs can be recovered rather than chipped. The stump is large and dense, and stump grinding is the sensible way to deal with it; cypress stumps are slow to rot.

Frequently asked questions

Do I need a wet site to grow bald cypress?

No. Cypress tolerates standing water, but it grows well on ordinary well-drained lawn soil once established. Wet sites produce more knees.

Can I stop the knees from forming?

Not reliably. Keeping the site drier reduces them. Cutting them off as they appear is the practical approach and does not harm the tree.

Is pond cypress the same tree?

Pond cypress is a close relative with a narrower form and needles pressed against the twigs. It is a smaller, slower tree and a good choice for tighter lots. The care is essentially the same.

How close to the house is too close?

Closer than the eventual spread of the canopy and the flare of the trunk. A cypress planted within a few feet of a wall will become a removal eventually. Twenty feet or more gives it room to be the tree it is.

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ArboristRX handles cypress pruning, assessment and removal in Osteen, DeBary, Edgewater and across Volusia County. Call (386) 444-5959.