Growing your results…
There's a number that should change how you think about your garden: 14%.
Research by entomologist Dr. Doug Tallamy and his team at the University of Delaware found that just 14% of native plant genera support 90% of the butterfly and moth species in any given region. A separate analysis by horticulturist Jarrod Fowler found that 15–60% of North American native bee species are pollen specialists — meaning they can only eat pollen from a specific group of plants, and nothing else.
These plants are the keystones. They are native species whose ecological contribution far exceeds what you'd expect from their share of the landscape. Plant them, and you're not just adding flowers — you're restoring the foundation of a food web.
This guide breaks down the top keystone plants by pollinator type, what the science says about each one, and how to sequence them for season-long impact.
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Before choosing plants, it helps to understand that pollinators need two distinct things:
Nectar and pollen — adult food. Flowers that provide energy for foraging bees, butterflies, moths, and hummingbirds.
Host plant tissue — larval food. The specific plant species on which butterflies and moths lay their eggs, and whose leaves caterpillars eat. No host plant, no reproduction.
Most garden plants marketed as "pollinator-friendly" only deliver the first. Keystone plants deliver both, often supporting dozens or hundreds of caterpillar species at the same time they're feeding adult insects. That's the multiplier effect that makes them so critical.
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North America has over 4,000 native bee species, and roughly a third are pollen specialists — they collect pollen exclusively from one plant genus or family. If that plant disappears from the landscape, so does the bee.
According to NWF data, the oak genus supports 952 caterpillar species — more than any other tree in North America. For bees, oaks are critical early-season pollen sources, releasing large quantities of pollen in spring when few other plants are blooming and bee colonies are rebuilding after winter.
Several native bee species are oak specialists, including some Andrena (mining bees) that rely on oak pollen for larval provisioning. Without oaks, those species have no breeding population.
Best species by region: White oak (Q. alba) for the East; Bur oak (Q. macrocarpa) for the Midwest and Great Plains; Valley oak (Q. lobata) for California.
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Goldenrod is arguably the single most important late-season keystone plant in eastern North America. It hosts 104 caterpillar species and supports 42 species of specialist bees — including Colletes simulans, Andrena asteris, and Melissodes desponsus that cannot complete their life cycles without it.
Goldenrod blooms in late summer and fall, filling a critical nectar gap when most spring and summer wildflowers have finished. The flowers are also visited by monarchs, painted ladies, and dozens of native bee generalists stocking up for winter.
A common misconception: goldenrod does not cause hay fever. Its pollen is too heavy and sticky to be windborne. The culprit is ragweed (Ambrosia spp.), which blooms at the same time and spreads its pollen by wind.
Top species: Stiff goldenrod (S. rigida), zigzag goldenrod (S. flexicaulis) for shade, seaside goldenrod (S. sempervirens) for coastal gardens.
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The sunflower genus hosts 66 caterpillar species and supports 50 specialist bee species — including the sunflower bee (Svastra obliqua), which is covered in specialized branched hairs adapted specifically to harvest sunflower pollen.
Native sunflowers differ from the ornamental annual varieties sold in garden centers. They're perennials, often spreading by rhizomes, with smaller flowers more accessible to a wider range of insects. Their seeds feed goldfinches, chickadees, and woodpeckers well into winter.
Top species: Thin-leaved sunflower (H. decapetalus), swamp sunflower (H. angustifolius) for wet areas, prairie sunflower (H. petiolaris) for dry sites.
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Asters are the fall counterpart to goldenrod — together they form the backbone of late-season pollinator support across most of North America. The genus hosts 100 caterpillar species and supports 33 specialist bee species, including pearl crescent butterflies, which use asters as their exclusive larval host.
Like goldenrod, asters are highly regional. Matching species to your ecoregion matters more here than with many other genera.
Top species: New England aster (S. novae-angliae), smooth aster (S. laeve), aromatic aster (S. oblongifolium) for drought-prone areas.
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Less famous than goldenrod or asters, mountain mint is described by many pollinator ecologists as "the cream of the crop" for sheer species diversity attracted. Its small white flowers bloom over a long season and are accessible to virtually every bee and butterfly family. A single patch in bloom will have dozens of species foraging simultaneously.
Mountain mint spreads by rhizome and can be aggressive in ideal conditions — give it room or use it as a meadow plant rather than a tidy border perennial.
Top species: Clustered mountain mint (P. muticum), hoary mountain mint (P. incanum) for drier soils.
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Butterflies have two distinct habitat needs: nectar plants for adults, and host plants for caterpillars. Without both in proximity, populations cannot sustain themselves. Many beautiful butterfly gardens fail on this count — they're full of nectar flowers but lack the host plants that allow reproduction.
Milkweed is the only larval host plant for monarch butterflies in North America. No milkweed, no monarch reproduction. It's that simple.
But milkweed supports far more than monarchs. Over 450 insect species use milkweed, including milkweed bugs, milkweed beetles, and specialist bees like the long-horned bee (Melissodes trinodis). The flowers provide high-quality nectar to generalist bees, bumblebees, and several swallowtail butterfly species.
The most important thing to know about milkweed for monarchs: avoid tropical milkweed (A. curassavica) in regions where it doesn't die back in winter. In the South and West, tropical milkweed persists year-round and can disrupt monarch migration by creating year-round breeding habitat at the wrong time of year. Use native species: common milkweed (A. syriaca) in the East, butterfly weed (A. tuberosa) for dry gardens, swamp milkweed (A. incarnata) for wet areas.
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The Prunus genus — which includes native wild cherries, plums, and chokecherries — is one of the top three keystone tree genera for butterfly and moth caterpillars, supporting over 450 species. It's also an early-season nectar source, blooming in spring before most wildflowers open.
For home landscapes, native chokecherry (P. virginiana) is a manageable size shrub/small tree that works in most temperate regions. Pin cherry (P. pensylvanica) and black cherry (P. serotina) are larger trees with higher wildlife value but require more space.
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Willows are among the most ecologically valuable keystone trees in North America, supporting over 450 caterpillar species — comparable to cherries and surpassed only by oaks. They bloom early in spring, producing catkins that are a critical pollen source for native bees emerging from hibernation when little else is available.
For garden-scale use, shrubby native willows like pussy willow (S. discolor) and sandbar willow (S. interior) are more manageable than large tree willows. Avoid non-native ornamental willows, which support a fraction of the native wildlife.
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A critical insight from Tallamy's research: 96% of terrestrial bird species in North America feed insects to their nestlings. Even seed-eating birds like chickadees and cardinals feed their young almost exclusively on caterpillars during the breeding season.
This means planting for birds is largely the same as planting for caterpillars — which means planting the keystone species that support the most Lepidoptera.
The top plants for insect-eating birds are the same genera that top the caterpillar-support lists:
For birds that primarily eat seeds and berries (rather than insects), add:
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One of the most important — and most overlooked — principles of pollinator gardening is bloom succession. Pollinators need food from early spring through late fall, and a garden that only flowers in summer creates a seasonal bottleneck.
A simple framework:
Early spring (March–April): Willows, maples, native cherries, and pussy willow provide critical pollen when native bees first emerge.
Late spring (May–June): Wild geraniums, native columbines, lupines, and redbud fill the mid-season gap.
Summer (July–August): Coneflowers, milkweed, native sunflowers, mountain mint, and Joe-Pye weed.
Fall (September–October): Goldenrods and asters are non-negotiable. These two genera alone sustain a large portion of the late-season pollinator community.
If your garden has gaps in any of these windows, pollinators will forage elsewhere — or not at all if they're in a heavily developed area with few alternatives.
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If you can only plant one tree: an oak (Quercus sp. native to your ecoregion). Nothing else comes close in ecological return per square foot of canopy.
If you can only plant one shrub: native willows for wet areas, native viburnums for drier sites.
If you can only plant one perennial: goldenrod (Solidago spp.) in the East and Midwest, native sunflowers (Helianthus spp.) across the country.
Then add milkweed for monarchs, and asters for fall.
Use our Native Plant Finder to filter keystone plants by pollinator type — bees, butterflies, and birds — and find species native to your ecoregion. You can also filter by nurseries that carry these species in your state.