What counts as native, and why it matters
A native plant is one that grew in the region before European settlement and evolved alongside the local insects, birds and soil. That matters for two reasons.
- Fit. A plant adapted to southeastern Pennsylvania clay, humid summers and freeze-thaw winters tends to need less help once it is established.
- Food. Native caterpillars and other insects can feed on native plants in a way most of them cannot on imported ornamentals, and birds raise their young on those insects. Native oaks support more species of caterpillar than almost any other group of plants in the East.
The word native on a nursery tag usually means native to North America. Several popular garden natives come from further south or west, and some of them are excellent here. A plant from the Southeast or the prairie states has not shared the same long history with local insects, though, and it may suit a given soil less well than the tag suggests. Where that applies, it is noted below.
| Condition | Plants |
|---|---|
| Dry shade under mature trees | Christmas fern, with serviceberry at the edge of the canopy where some light gets in |
| Acidic, well-drained shade | Mountain laurel and inkberry holly, typically under oaks and pines where leaf litter keeps the soil acidic |
| Moist shade | Golden ragwort as a groundcover, with Virginia sweetspire behind it |
| Wet clay or a low corner | River birch, Virginia sweetspire and inkberry holly |
| Full sun and heavy clay | Ninebark, arrowwood viburnum, black-eyed Susan and wild bergamot |
| Full sun and dry, lean soil | Little bluestem and purple coneflower; skip the fertilizer for both |
Trees
Serviceberry is the best small native tree for most Main Line yards. White oak is the long-term tree. Plant it small, since it transplants poorly once it has a big taproot, and plant it well away from the house.
Flowering dogwood needs an honest note. Dogwood anthracnose, a fungal disease, has killed a great many of them, and it is worst in shady, damp spots with little air movement. Give a dogwood morning sun, open air and water in dry spells, and it has a fair chance. Disease-resistant hybrids exist, but those are crossed with the Asian kousa dogwood and are not natives.
| Plant | Light | Soil | Deer | Notes |
|---|---|---|---|---|
| Serviceberry | Sun or part shade | – | Usually spared serious damage | White flowers in early spring, June berries the birds take, orange-red fall color |
| Eastern redbud | – | Tolerates clay; dislikes wet feet | Browsed hard | Pink-purple flowers on bare branches in April; stays small, not long-lived |
| River birch | – | Wet or clay-heavy low spots | – | Large, peeling cinnamon bark; resists the borer that kills white-barked birches; drops twigs, needs room |
| White oak | – | – | Young oaks browsed hard | Slow, enormous at maturity, valuable to wildlife |
| Flowering dogwood | Morning sun, open air | – | Browsed hard | Anthracnose is worst in shady, damp spots |
Shrubs
Two of the most useful shrubs here are not strictly Pennsylvania natives. Inkberry holly’s wild range sits on the Atlantic coastal plain just east of here rather than in Pennsylvania proper. Oakleaf hydrangea is a Southeastern native, but it is a reliable shade shrub here if the soil drains. Smooth hydrangea is the hydrangea that is native to Pennsylvania.
Arrowwood viburnum has one catch: the viburnum leaf beetle, an introduced pest that can strip it, so it needs watching. Mountain laurel, the Pennsylvania state flower, is the hardest of these to place. It wants the kind of soil found under oaks, and it sulks in heavy clay or in the limy soil along a concrete foundation.
| Plant | Light | Soil | Deer | Notes |
|---|---|---|---|---|
| Inkberry holly | – | Wet; acidic | Usually spared serious damage | Evergreen in the role boxwood usually plays; goes bare at the base with age, so compact selections hold shape better |
| Virginia sweetspire | Part shade | Wet | – | White spikes in early summer, deep red in fall; suckers into a mass, useful on a bank |
| Oakleaf hydrangea | Shade | Must drain | – | Southeastern native |
| Smooth hydrangea | – | – | – | The hydrangea native to Pennsylvania |
| Ninebark | Sun | Dry ground or clay | – | About as tough as a shrub gets |
| Arrowwood viburnum | Sun or part shade | Clay | Seldom touched | Feeds birds in fall; watch for viburnum leaf beetle |
| Mountain laurel | Part shade | Acidic, well-drained, humus-rich | Browsed in winter | Pennsylvania state flower |
Perennials, grasses and ferns
Purple coneflower is native more to the Midwest and South than to Pennsylvania, but it behaves like a native here. Black-eyed Susan is short-lived but reseeds; its longer-lived cousin, orange coneflower, gives permanence. Little bluestem flops in rich, wet or fertilized soil, so keep it on a dry, sunny, lean spot.
A planting of natives in a bed reads as intentional when it is grouped in drifts, given a clean edge and mulched, rather than scattered one of each.
| Plant | Light | Soil | Deer | Notes |
|---|---|---|---|---|
| Purple coneflower | Sun | Dry, lean; no fertilizer | Blooms often taken | Native more to the Midwest and South |
| Black-eyed Susan | Sun | Handles heavy clay | – | Short-lived but reseeds |
| Orange coneflower | Sun | – | – | Longer-lived cousin of black-eyed Susan |
| Wild bergamot | Sun | Handles heavy clay | Seldom touched | Aromatic, lavender flowers in midsummer, popular with bees; some cosmetic powdery mildew by late summer |
| Little bluestem | Sun | Dry, lean | Seldom touched | Blue-green in summer, copper through winter; flops in rich soil |
| Golden ragwort | Moist shade | Moist | Seldom touched | Low, mostly evergreen groundcover, yellow in spring; spreads freely, so give it room or an edge |
| Christmas fern | Shade, including dry shade under trees | – | Seldom touched | Evergreen and clump-forming; one of the most useful plants in an older, tree-heavy yard |
The first year decides it
Native does not mean no water. Every new plant, native or not, arrives with its roots confined to a nursery root ball and has to grow out into the surrounding soil before it can find water on its own.
Through the first growing season the usual guidance is about an inch of water a week, from rain or a hose, applied deeply and less often rather than a little every day. Check the soil a few inches down before watering; on clay, too much water drowns roots as surely as too little dries them. Trees and larger shrubs typically need that attention for two seasons or more.
Plant at the right depth, with the root flare at or just above grade, and back-fill with the soil that came out of the hole. Heavily amending a single hole in clay creates a bowl that collects water around the roots. Mulch two to three inches deep, kept off stems and trunks.
And expect patience: many perennials put their first season into roots, grow modestly in the second, and fill in by the third. Weeding in those first two years is the main job.
Mixing natives with what is already there, and the deer
There is no need to rip out an established garden to add natives. A clipped hedge, a lawn and a native border can live together perfectly well. The sensible order is to replace plants as they fail, add natives where there is space, and remove the invasive ones that spread into woods, such as burning bush, Japanese barberry and English ivy.
Around old oaks and other mature trees, keep new beds shallow over the root zone and do not pile soil against trunks or regrade under the canopy.
Deer browse plenty of natives. The Deer column in each table above shows which ones get hit hard, which get browsed in winter, and which are seldom touched.