Mature size & growth rate

How big does Arborvitae (Thuja occidentalis) get?

Also called arborvitae, eastern arborvitae, American arborvitae, white cedar, eastern white cedar, northern white cedar, tree of life.

More about arborvitae

About Arborvitae

Thuja occidentalis · also called arborvitae, eastern arborvitae · houseplant

Arborvitae is a hardy evergreen conifer grown outdoors for hedging, screening and in large containers. It wants full sun, deep well-drained soil and even moisture while establishing. It is not on the ASPCA list, but its foliage and oils contain thujone — a neurotoxin — so treat it as toxic to pets and livestock and verify any exposure with your vet.

Mature size: Species can reach 12-20 m (40-60 ft) tall and 3-5 m (10-15 ft) wide if unpruned, but is usually kept far smaller as a hedge. Compact cultivars like 'Smaragd' (Emerald Green) mature around 3-4 m (12-14 ft) tall and under 1.2 m (3-4 ft) wide; dwarf forms such as 'Danica' stay under 1 m.

Indoor size vs how big it gets in the wild

Arborvitae is a tree at heart. Indoors a pot and your ceiling keep it to species can reach 12-20 m (40-60 ft) tall and 3-5 m (10-15 ft) wide if unpruned, but is usually kept far smaller as a hedge. compact cultivars like 'smaragd' (emerald green) mature around 3-4 m (12-14 ft) tall and under 1.2 m (3-4 ft) wide, but in the ground it is a different scale of plant entirely (dwarf forms such as 'danica' stay under 1 m.). Indoors and in a pot, expect species can reach 12-20 m (40-60 ft) tall and 3-5 m (10-15 ft) wide if unpruned, but is usually kept far smaller as a hedge. compact cultivars like 'smaragd' (emerald green) mature around 3-4 m (12-14 ft) tall and under 1.2 m (3-4 ft) wide. In the ground with no restriction it is a completely different plant — dwarf forms such as 'danica' stay under 1 m. — which is why the pot, the light and the pruning matter so much for the size you actually end up with.

It gains real height on a trunk or main stem, adding a tier of leaves a year and eventually reaching for the ceiling — this is a plant you grow up, not out.

Growth rate and years to mature

Arborvitae is a moderate grower. Realistically, expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Its feeding profile backs this up: feed in early spring with a balanced slow-release fertiliser or one formulated for evergreens/conifers as new growth begins. established plants in decent soil need little feeding; avoid heavy late-summer feeding, which pushes soft growth vulnerable to winter burn. container-grown plants need regular feeding through the growing season.

Want this turned into the right next pot at the right moment? The pot size calculator and the arborvitae repotting guide cover when and how much to size up — pot size is one of the biggest levers on how fast arborvitae grows.

How to keep arborvitae smaller

You are not stuck with the maximum size. For arborvitae specifically, these are the levers, in order of impact:

The decisive tool is the secateurs: arborvitae can be topped (cut the main growing tip) to cap its height and force a bushier, shorter shape.
Keeping it deliberately pot-bound in a snug container slows the whole plant and limits ultimate size.
Prune in spring so it heals fast; remove the tallest leader back to a node to reset the height.
Expect to top or hard-prune it every year or two — left alone it heads for the ceiling.

The keep-it-smaller method, step by step

Pick the new height. Decide how tall you want arborvitae and find a leaf node or branch point just below that.
Top the main stem. Cut the main growing tip cleanly just above that node in spring; this permanently caps the height and forces side branches.
Keep the pot snug. Avoid jumping to a much bigger pot — a slightly restricted rootball keeps the whole plant smaller.
Maintain the shape. Prune back the tallest new leaders each spring to hold it at the height you chose.

How to grow arborvitae bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for arborvitae the accelerators are:

It already wants the bright light it needs; warmth, a yearly pot-up and spring-summer feed are the accelerators.
Pot up a size every year or two while young; restricted roots are the main thing holding height back.
Feed regularly through the growing season and keep it warm — height comes from sustained good conditions.

Light is almost always the ceiling. The arborvitae light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When arborvitae outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for arborvitae:

The top leaves pressing against or bent by the ceiling — the classic "this is now too tall indoors" sign.
It has to be moved away from a light source it has literally outgrown.
Roots filling the largest pot you can reasonably keep indoors — at that point it is top-or-prune or move it outside (if hardy).

If it is the pot rather than the room, it is a repotting job, not a goodbye — see the arborvitae repotting guide. If you want more of this plant instead of a bigger one, the arborvitae propagation guide turns prunings into new plants.

Arborvitae size — frequently asked questions

How big does arborvitae get?

Arborvitae reaches species can reach 12-20 m (40-60 ft) tall and 3-5 m (10-15 ft) wide if unpruned, but is usually kept far smaller as a hedge. compact cultivars like 'smaragd' (emerald green) mature around 3-4 m (12-14 ft) tall and under 1.2 m (3-4 ft) wide when grown indoors, and far larger where it grows unrestricted (dwarf forms such as 'danica' stay under 1 m.). It gains real height on a trunk or main stem, adding a tier of leaves a year and eventually reaching for the ceiling — this is a plant you grow up, not out.

Is arborvitae slow or fast growing?

Arborvitae is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Arborvitae is a tree at heart. Indoors a pot and your ceiling keep it to species can reach 12-20 m (40-60 ft) tall and 3-5 m (10-15 ft) wide if unpruned, but is usually kept far smaller as a hedge. compact cultivars like 'smaragd' (emerald green) mature around 3-4 m (12-14 ft) tall and under 1.2 m (3-4 ft) wide, but in the ground it is a different scale of plant entirely (dwarf forms such as 'danica' stay under 1 m.).

How long does arborvitae take to reach full size?

Roughly three to six years to reach mature indoor size, gaining a steady amount each growing season. Light, pot size and feeding move that timeline more than anything else.

How do I keep arborvitae smaller?

The decisive tool is the secateurs: arborvitae can be topped (cut the main growing tip) to cap its height and force a bushier, shorter shape. Keeping it deliberately pot-bound in a snug container slows the whole plant and limits ultimate size. Prune in spring so it heals fast; remove the tallest leader back to a node to reset the height. Expect to top or hard-prune it every year or two — left alone it heads for the ceiling.

How can I make arborvitae grow bigger or faster?

It already wants the bright light it needs; warmth, a yearly pot-up and spring-summer feed are the accelerators. Pot up a size every year or two while young; restricted roots are the main thing holding height back. Feed regularly through the growing season and keep it warm — height comes from sustained good conditions.