Can You Trim Bottom of Arborvitae? | The Branch-Safe Way

Yes, trimming the bottom of arborvitae is fine when you thin or shorten lower branches selectively, cutting only into green, flexible growth and leaving old brown wood untouched.

One wrong cut turns a dense green base into a bare spot that never fills back in. The rule is simple: arborvitae do not regrow well from leafless stems, so every cut needs to leave foliage behind. The fix for a sparse bottom is usually light, patient trimming and a better shape—not a hard chop. Here is what actually works, when to do it, and which mistakes guarantee a leggy hedge.

Why the Bottom of Arborvitae Goes Brown

The lower branches brown out for one main reason: they are not getting enough sunlight. Most arborvitae hedges are trimmed into a shape that is narrow at the base, wide in the middle, narrow at the top—an egg form that blocks light from reaching the lower half.

When light cannot get to the bottom foliage, those needles drop and the wood stays bare. The fix is not to cut the brown away; it is to reshape the plant so the base is wider than the top. This lets sunlight and air circulation reach the lower branches and keep them green.

What Not to Do With Arborvitae Trimming

• Never cut into brown, leafless interior wood. Those bare stems will turn green again in only one case—never. The plant will simply sit there with a bald patch.
• Do not “top” the arborvitae. Cutting the top back into leafless wood ruins the shape and triggers no useful regrowth.
• Do not shear the whole plant into an egg shape. A narrow top and wide middle sounds tidy but it shades the base and guarantees a sparse bottom next season.
• Avoid heavy pruning in one session. Remove no more than one-third of the live foliage area per growing season.
• Do not prune during drought, waterlogged soil, or winter dormancy. Stressed plants struggle to push new growth from the cuts.

How to Trim the Bottom Safely

Thinning and selective reduction keeps the plant full and healthy. Here is the step sequence that works across all arborvitae varieties, including the popular Emerald Green.

1. Cut only the new growth. Reach into the foliage and remove small amounts of green tip growth, never the older interior stems. The plant stays naturally tapered, wider at the base than at the top.
2. Work from the bottom upward, keeping a slight slope. A 5–10 degree angle away from the trunk helps light reach the base. Start at the bottom edge and trim upward, maintaining that taper.
3. Use reduction cuts instead of random shearing. Find a branch you want to shorten, follow it back to a sturdy side branch that is at least one-third the diameter of the branch you are cutting, and make the cut right there. This keeps a natural shape and hides the cut point in the foliage.
4. Remove dead or badly placed branches at the trunk—but only when necessary. If a branch is rubbing another or clearly dead, cut it flush to the trunk. Otherwise leave the brown interior alone; it will not refill, but the green outer foliage will eventually cover it if light conditions improve.
5. Check your work from ten feet away. The plant should look wider at the base than the top. If the bottom looks skinny, you have trimmed too much.

When Is the Best Time to Trim?

The sources disagree on the exact calendar window, but they agree on the principle: trim during active growth when the plant is pushing new foliage. Here is the honest range from the experts.

The safest bet for a US yard: trim lightly from mid-spring through early summer, stop before the heat of late July, and never cut into old wood. Minor broken or stray branches can be removed any time of year.

What the Timing Conflict Means for You

The disagreement between late-spring-trimming sources and late-summer-trimming sources comes down to climate and plant age. In hotter southern zones, late spring is the safer window because the plant has energy to heal before summer stress. In cooler northern zones, late summer works well because the plant is still growing but past the fastest growth flush. If you can only pick one window, choose late spring—the plant is ready to recover, and you can see exactly where the green growth is.

Young, fast-growing arborvitae in their first three years can sometimes handle a second light trim in early fall. Older, established plants need only the one annual pass.

Proper Trimming Cuts (The Right Angle and Depth)

Every cut you make should preserve at least one green stem or bud beyond the cut so the branch has living needles to pull energy from.

A reduction cut (shortening a branch back to a side branch) is better than a heading cut (randomly lopping off an end). The side branch takes over as the new growing tip, and the plant stays full. The same logic applies when trimming the bottom: reach into the dense leaf mass and shorten the longest branches by following them back to a leafy fork.

Arborvitae grown as a hedge can be trimmed more uniformly, but the same rule holds—never go past the point where there is still green growth. If you cut into brown, the hedge will have visible holes until something grows over them, which may take several years.

Common Arborvitae Trimming Mistakes That Kill the Base

Finish With a Taper, Not a Straight Wall

The single action that protects the bottom of an arborvitae for the rest of its life: keep the base 6–12 inches wider than the middle, and keep the middle wider than the top. That slope lets sunlight hit every branch. Check the shape from the side after every trim, and if the lower half looks skinny, you have overdone it. Lighten up next season, and let the foliage fill back in. Young, rapidly growing plants sometimes recover in one year; older ones take two or three.