Photo: John B., CC BY 2.0 · Wikimedia Commons

Atlantic White Cedar

Chamaecyparis thyoides

Also called southern white cedar, swamp cedar, white cypress.

The only false cypress native to the eastern states, a narrow blue-green evergreen of coastal bogs that makes a year-round screen on wet, acid ground.

EvergreenTolerates wet soilHedge or screenWinter interest

Type: Medium tree
Mature height: 40–60 ft
USDA zones: 3–9
Growth rate: Medium
Sun: Full, Part
Soil moisture: Average, Wet
Grows wild in: The coast, stream banks, swamps and wet flats
Native range: 17 states, north to Maine, south to Florida and west to Mississippi
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Alabama, Connecticut, Delaware, Florida, Georgia, Maine, Maryland, Massachusetts, Mississippi, New Hampshire, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina and Virginia
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Atlantic white cedar is a columnar evergreen that grows in dense stands in the freshwater swamps and bogs of the Atlantic and Gulf coasts. Colonists used it for shingles and small boats, and logs buried for centuries in New Jersey swamps have come up sound. It has declined since European settlement through drainage, farming and logging. New York lists it as threatened and Georgia as rare, and it is presumed gone from Pennsylvania. In gardens it is the hardiest false cypress in the North. Plant a group to screen a wet corner, a pond edge or a rain garden.

Size, growth and what to expect

Atlantic white cedar grows at a medium pace, about a foot and a half a year in our growth estimator. On good sites it adds a foot to a foot and a half a year until it is 40 to 50 years old. Expect 40 to 60 feet tall and 10 to 20 feet wide. Trees in the open bear cones at 3 to 5 years.

Pollen is shed in March and April. The round cones, about a quarter inch across, ripen from bluish purple to brown in September and October. The tiny winged seed drifts down from October through winter. The foliage feeds the caterpillars of Hessel's hairstreak, a butterfly.

It grows wild in a belt 50 to 130 miles wide along the coast from southern Maine to northern Florida and west to southern Mississippi. Some trees have lived 1,000 years, though stands seldom pass 200.

How to grow Atlantic White Cedar

Atlantic white cedar wants full sun or light shade and an acid soil that stays moist to wet. It prefers sandy or peaty ground. It does not stand drought. Its roots are shallow, so give it shelter from strong wind. Plant it 15 feet from a wall, and set trees 10 feet apart for a screen. Keep it more than 50 feet from overhead wires.

Saplings ship bare-root or potted. Plant in early spring or fall, in a hole wider than the roots and no deeper. On soggy ground set it on a low mound, since in the wild it grows on hummocks above the water. Put the native soil back in, and keep the mulch clear of the stem. Seed needs one to three months of cold, damp storage in the refrigerator. Sow it in spring on the surface of wet peat or sand, where it gets light. Keep the mix wet until the seedlings are up.

Water weekly through the first two summers, and in dry spells after that. Deer browse it hard in winter and can kill young trees, so fence or cage them until they are well above browse height. Meadow mice girdle young stems, so pull the mulch back from the trunk in winter. It seldom needs pruning.

Atlantic white cedar carries male and female cones on the same tree and the wind pollinates it, so one tree bears alone. It usually bears a fair to excellent seed crop every year. No insect or disease is a serious threat, though bagworms, juniper blight and root rot turn up. Heavy ice and snow can break or topple young trees.

Heights and zones are typical ranges for the species in cultivation; local conditions and seed source shift them.

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