Hollow is not automatically dangerous, and this is where homeowners get oversold more than anywhere else on this list. A tree is a tube, and a tube carries bending load in its outer wall — a hollow stem with a thick continuous shell can be as strong as a solid one. What actually matters is the thickness of remaining sound wall relative to trunk radius, and whether the cavity is closed or has an open slot in the side. An open slot is worse than a sealed hollow of the same size because the tube can no longer resist flattening inward. Neither of those is visible by looking at the hole. In Greenwood — Old Town Greenwood, Green Valley and Imperial Hills included, that's normally a hazardous tree removal job at $800–$5,000. Within weeks.
Why this comes up in Greenwood
Median year built is 1996 across 27,721 housing units (ACS 2019-2023, tables B25034/B25035). About 27% predates 1980 — including a small pre-1940 Old Town core — but roughly 42% went up after 2000. The practical result: 70-to-90-year-old shade trees hanging over Old Town roofs, and 10-to-20-year-old nursery stock in the subdivisions east of I-65.
Greenwood's canopy
Two separate canopies in one city. The pre-1960 blocks around Old Town and near County Line Road hold Greenwood's only genuinely mature shade trees — just 9% of the housing stock predates 1960 — while the subdivisions east of I-65 are 2000s-era plantings still small enough to prune off a ladder. Ash is functionally gone: emerald ash borer has been confirmed in Indiana since April 2004 and is now in all 92 counties.
Johnson County rules
No permit is required to remove a tree on private property in Greenwood. Tree rules in the city code are all about new development and the public way: the UDO's landscaping standards require street trees along frontage and give credit for preserving existing large-caliper trees, separate provisions restrict planting in the public way, and the Stormwater Department's Easement Encroachment Permit is required before planting any tree or shrub inside an existing drainage or utility easement. The specific UDO section numbers and planting ratios could not be verified against the live code — confirm with Planning and the Stormwater Department. Cutting down your own backyard tree needs nothing.
The tree lawn in Greenwood
The strip between sidewalk and street is public right-of-way. Greenwood's UDO governs where required street trees are placed relative to the curb and sidewalk, but that placement rule could not be confirmed against the live code, so check with the Planning Department before assuming a given curb-strip tree is the city's problem or yours. One exception worth knowing: County Line Road, Greenwood's northern boundary, is under the control of the City of Indianapolis, not Greenwood, per the city's own comprehensive plan.