Native Plants for Connecticut

Connecticut's central lowland is split by traprock: hard basalt ridges left by ancient lava flows, running north from New Haven in a broken line. They are steep, west-facing on the exposed side, and they shed water fast.

Ridge-top conditions there are genuinely harsh. Soil is shallow over rock, summer sun is direct, and the communities that persist are dry, sometimes with species more typical of much drier regions. For a gardener with a rocky, baking, south-facing site, that is the model to plant toward, and little bluestem, butterfly weed, and the dry-site asters and goldenrods belong.

On either side of that spine, the picture is more familiar New England: mixed hardwood forest on acidic glacial soils, with richer bottomland along the Connecticut River.

The northwest corner is different again, higher and colder, with marble valleys whose calcium-rich soils support species absent from the rest of the state.

The Sound moderates the shore

Long Island Sound gives coastal Connecticut the mildest winters in the state, and the shoreline towns run a full hardiness zone above the northwest hills. Salt spray and wind apply near the water, and the coastal natives handle both.

The Sound also lengthens autumn considerably, which makes fall the best planting season along the shore. Inland and in the hills, spring planting is safer.

Deer are the practical constraint

Connecticut has among the higher deer densities in the region, and in much of the state the limiting factor on a native planting is not soil or cold but browsing. This is worth planning for honestly at the design stage rather than discovering in May.

The aromatic, fuzzy, and bitter-leaved natives get eaten last: mountain mint, wild bergamot, anise hyssop, ferns, and most of the ornamental grasses. Nothing is truly deer-proof in a hard winter, but a planting built mostly from low-preference species survives where a bed of asters and coneflowers is grazed flat.

Fencing a new planting for its first two seasons, while roots establish, makes a larger difference than any repellent.

Confirming what is native to your county

The Connecticut Botanical Society maintains a long-running flora of the state, and the Connecticut Agricultural Experiment Station publishes practical research on native plants and invasive species. Native Plant Trust covers Connecticut in its regional conservation program.

Sources: Connecticut Department of Energy and Environmental Protection (natural communities and traprock ridges); Connecticut Botanical Society (state flora); USDA PLANTS Database (native status by state).