How to Remove It

Don't just cut it down

Cutting or mowing Tree of Heaven without also treating it chemically triggers aggressive root suckering. You'll likely end up with more stems than you started with, not fewer. Even cut-stump herbicide treatment — which works well on many other invasive trees — is not reliably effective against Tree of Heaven's root suckers. It needs to be treated as a standing, living tree.

What actually works

The standard effective methods apply herbicide to the living tree so it translocates down into the root system, rather than treating a stump after the fact.

Basal bark treatment — for trees under about 6″ in diameter. Herbicide is applied as a solid band around the lower 12–18″ of the trunk.
Hack-and-squirt (frill-and-girdle) — for trees over about 6″ in diameter. Make one downward hack/cut per inch of trunk diameter (at least two even on small stems), spaced around the trunk with living bark left between them, and apply herbicide directly into each cut.
Herbicides commonly used for both methods include triclopyr, imazapyr, and glyphosate. Always follow the product label and any local regulations — this page is general background, not a substitute for label instructions, and larger or hazardous trees are often worth hiring a licensed applicator or arborist for.
If a tree has to come down for safety reasons before treatment can take full effect, treat it with herbicide first, wait about 30 days for symptoms to show, then cut.

Timing matters

Apply herbicide from mid-to-late summer into fall — roughly July onward through when the leaves start changing color. That's when the tree is actively moving sugars down into its roots, which carries the systemic herbicide with them. Spring and early-summer treatment is noticeably less effective.

Hand-pulling seedlings

Hand-pulling only works on true seedlings, not root suckers — suckers are fed by an established root system and just keep coming back. For real seedlings: pull in moist soil, and get the entire root out, since any fragment left behind can resprout. Seedlings develop a substantial taproot within about 3 months, after which hand-pulling gets a lot harder — worth doing while they're small, not a general-purpose control method for anything established.

Follow-up is not optional

Treat this as a multi-year project. Come back the following season(s) to check for resprouts around treated trees and new seedlings nearby, and re-treat as needed. A single treatment rarely finishes the job on its own.

Sources