Plant One Native Tree This Fall. You’ll Feed Wildlife for Decades.

A single oak can host hundreds of kinds of caterpillars. A single Bradford pear hosts almost none. Both are “trees.” Only one of them feeds the chickadee on your fence.

If you’re going to plant one tree, plant it this fall, and make it a native. The rest is getting it in the ground so it lives.

Why a native tree feeds more wildlife

Most caterpillars can only eat a few kinds of plants. That matters because caterpillars are what most backyard birds feed their chicks: about 96 percent of terrestrial birds raise their young on them. A tree that caterpillars can’t eat is a tree that nesting birds can’t use.

A few native plants do most of the work. In a national analysis, 90 percent of caterpillars depend on just 14 percent of native plants. Oaks top the list. They host more than 950 species of butterfly and moth caterpillars, more than any other tree in North America.

The same pattern shows up from the bird’s side. When researchers tracked Carolina chickadees around Washington, D.C., the birds nested more in yards with lots of native trees, and oaks were their top choice in 70 percent of the yards studied. Native trees held scores of caterpillars, while most of the introduced plants had one or fewer. Raising one brood of five chickadees can take 6,000 to 9,000 caterpillars.

Tallamy’s counts run more conservative, and just as lopsided: oaks at up to 557 species, wild cherry and plums at 456, maples at 297, and elms at 215. Introduced Bradford pear and crape myrtle? “Almost no caterpillars.” Pretty looks, empty pantry.

Why fall works

Spring planting has a catch. You never know whether the weather will stay mild or jump straight to summer heat. In fall, you know you have six to eight weeks of cooling temperatures ahead.

Roots are on a different schedule than leaves. They put on a flush of growth in fall, when soil temperature and moisture are moderate, and keep growing after the leaves drop, until the ground freezes. That can be as late as February in parts of Illinois. A tree planted now gets a few extra months of root growth to settle in before its first summer.

The thing to get right is timing. Plant too late, and cold soil slows root growth before the tree has anchored itself. So go early in fall, mulch to even out soil temperature swings, and water if it’s dry so the tree goes into winter well hydrated. Nursery stock can run thinner in fall, so call ahead.

How to plant it

The basics are the same as in spring. Pick the right tree for the spot. Dig the hole 2 to 3 times as wide as the root ball, but no deeper than the root collar, the flare where the trunk widens at the base. Roots spread sideways more than down, so they need loosened soil to move into, and a trunk buried past its flare can rot.

How deep to dig

Wide and shallow beats narrow and deep.

Based on Illinois Extension planting guidance. Redrawn, not to scale.

Loosen the root ball and fix any circling roots. Backfill with the soil you dug out; amendments usually aren’t needed. Mulch, water well, and keep watering until the ground freezes, then protect the trunk from animals, mowers, and string trimmers.

Which tree to plant

Start with what’s native where you live. Oaks lead nationally, followed by willows, cherries and plums, pines, and poplars and aspens, according to a national analysis of host-plant data across US counties. Not every one of those fits a small yard, so check mature size before you buy.

The National Wildlife Federation’s keystone-plant lists give the top caterpillar plants for 10 ecoregions, a better guide than any one-size list. They’re at nwf.org/KeystonePlants. Take yours to a local nursery that sells natives.

An oak is a long game. Tallamy puts it this way: a single acorn, planted, will support “tens of thousands of individuals of thousands of species” over the tree’s life. If an oak won’t fit, our native plants and yard as habitat pages have more ideas, and if natives sound like a hassle, they aren’t.