Native trees and shrubs for bees: pollen, nectar, nesting and a bloom calendar from willow to witch hazel

Most of the flowers in an eastern landscape are on trees and shrubs, not in beds, and most of them open before a perennial border has done anything. Honey bee colonies sampled for a year in Michigan, Texas and Florida took 61 to 83 percent of their spring pollen from trees and shrubs. An American basswood (Tilia americana) flowers for about two weeks in June over a crown as wide as a house, and 66 kinds of insects have been recorded pollinating it. Of the roughly 770 bee species native to the eastern United States, about a quarter raise their young on the pollen of one plant group, and the largest set of them tied to any woody plant, 14 species, depends on one genus: willow.

Who the bees are

The United States has more than 4,000 species of native bees. The honey bee is not one of them; it came from Europe and lives in a hive of thousands, while most of our natives are solitary: one female digs or builds a nest and stocks each cell with pollen and nectar for a larva she never sees. About 70 percent of native species nest in the ground and about 30 percent in cavities, old beetle tunnels in dead wood or the hollow and pithy centers of stems. Bumble bees are the social exception, nesting in abandoned rodent burrows and under grass tussocks; their mated queens winter an inch or two down in the soil, under leaf litter where there is any.

Roughly a quarter of the 770 bee species native to the East are pollen specialists, whose larvae eat the pollen of one plant family or a few related genera and nothing else. Jarrod Fowler’s catalog for the Northeast counted 61 such species tied to 33 plant genera, and in the wider eastern list nearly 60 percent of the specialists are rare.

Why the woody plants carry most of the food

A tree holds its flowers in three dimensions over a crown 30 to 60 feet across; a bed holds them on one plane, and in the Mid-Atlantic mostly after mid June. That is the argument of Philip Donkersley’s review “Trees for bees”: woody plants are more efficient forage because of their absolute resource density, and honey bees show a measurable preference for trees even where trees are sparse. In a year of sampling honey bee colonies in four states, spring pollen came 61 percent from trees and shrubs in Michigan, 78 percent in Texas and 83 percent in Florida, and the important pollen types in Michigan over the year included maple, willow, plum, locust, chestnut and sumac.

The numbers for single plants are large. A male pussy willow (Salix discolor) catkin holds about 270 flowers; five catkins from a Maine bog averaged 200 nectar-bearing flowers each, with more sugar than any of the 17 other plants measured beside them. American basswood opens in June for about two weeks, 4 to 40 flowers to a cluster, with nectar heavy enough that beekeepers call it the bee tree, and a pollination study found 66 insect species from 29 families on it, bees and flies by day and moths at night.

Pollen, nectar and the trees that give only one

Nectar is sugar, the fuel for flight and, in a hive, for wax and honey. Pollen is protein and fat, and it is what a larva eats; a solitary female provisions her nest with pollen moistened with nectar and nothing else. A plant can be rich in one and useless for the other. The wind-pollinated trees, oaks, hickories, walnuts, birches, alders, hazels and hornbeams, shed pollen by the pound and, needing no insect, offer no nectar. They still feed bees. Oak pollen was among the main pollen types honey bees brought home in California, Texas and Florida, and chestnut pollen turned up in Michigan colonies. American hazelnut (Corylus americana) sheds pollen in late winter and early spring, and our oaks, from dwarf chinquapin oak (Quercus prinoides) to cherrybark oak (Q. pagoda), shed theirs as they leaf out. Chestnuts go further: honey bees carry their pollen home, and a mining bee, Andrena rehni, is a recorded chestnut pollen specialist from Georgia to Massachusetts, which gives an Allegheny chinquapin (Castanea pumila) a claim no oak has.

The bloom calendar, March to November

Dates are for the Mid-Atlantic.

• March. Red maple (Acer rubrum) is among the first trees to flower, weeks before its leaves, with pollen and nectar. Willows open in March and April, and in many places they are the first and most important bee forage of the year; queen bumble bees just out of the ground depend on them. Spicebush (Lindera benzoin) flowers on bare twigs in March and April, an early nectar source for small bees and flies.
• April. Downy serviceberry (Amelanchier arborea) and Allegheny serviceberry (A. laevis) flower for about a week, worked by mining bees and sweat bees. Eastern redbud (Cercis canadensis) flowers on bare wood from late March into May and rates as a honey plant; mining bees, sweat bees, mason bees, carpenter bees and bumble bees all use it, and leafcutter bees cut circles from its leaves to line their nests. American plum (Prunus americana) and beach plum (P. maritima) draw the same crowd. Carolina silverbell (Halesia tetraptera) opens with its leaves from late April, and Tennessee beekeepers rate it as a honey plant. Flowering dogwood (Cornus florida) follows, and black huckleberry (Gaylussacia baccata) and the blueberries open their bells from late April.
• May. Blackhaw (Viburnum prunifolium), nannyberry (V. lentago) and arrowwood viburnum (V. dentatum), mostly for mining bees and sweat bees. American crabapple (Malus coronaria) for two weeks, for native bees and honey bees. Black cherry (Prunus serotina), a native we do not sell, worked by several bees including the honey bee, and a host for many caterpillars. Tuliptree (Liriodendron tulipifera), a honey tree visited by flies, beetles, honey bees and bumble bees in that order, though not a tree for a small yard. Black locust (Robinia pseudoacacia) in May or June, pollinated mainly by bees. Black gum (Nyssa sylvatica), small greenish flowers on a good honey tree. American holly (Ilex opaca) from May into June, visited by bees, wasps, ants and night moths. Ninebark (Physocarpus opulifolius), black chokeberry (Aronia melanocarpa), American persimmon (Diospyros virginiana) and mountain laurel (Kalmia latifolia), whose spring-loaded anthers are fired by bumble bees, run from May into June.
• June. Basswood, for two weeks. Black elderberry (Sambucus canadensis). Staghorn sumac (Rhus typhina) in June and July. Silky dogwood (Cornus amomum) in May and June. Allegheny chinquapin from late May into July. Rosebay rhododendron (Rhododendron maximum) from June to August. Buttonbush (Cephalanthus occidentalis), which we do not sell, from June to September.
• July and August. Sourwood (Oxydendrum arboreum), among the latest trees to bloom, from late June into August. Sweet pepperbush (Clethra alnifolia) from late June to August; in a Connecticut trial at least 80 percent of its visitors were bumble bees.
• October and November. Witch hazel (Hamamelis virginiana) opens its yellow ribbons as the woods go bare. Bees, flies, gnats and small wasps have been recorded on it, but its main pollinators are probably night-flying moths; by then the year’s last bees are on asters and goldenrod.

The specialists: bees that need one kind of tree

Fowler and Droege’s list of 200 eastern pollen specialists holds 14 species that collect pollen from willow and nothing else, more than for any other woody genus, all mining bees but one tiny Perdita, flying from March into June while the catkins are open. The blueberry genus (Vaccinium) has ten, and black huckleberry shares one of them, Andrena carolina. The best known is the southeastern blueberry bee (Habropoda laboriosa), which ranges north into New England. It emerges in early spring, lives three to five weeks as an adult and buzz-pollinates blueberry bells that honey bees handle poorly; in that time one female can visit 50,000 flowers and set more than 6,000 berries. Before the blueberries open she takes pollen from redbud, and the males visit plum, viburnum, azalea and even oak.

The rest of the woody list: four mining bees restricted to the shrub dogwoods, of which silky dogwood and gray dogwood are two; three holly specialists, among them Colletes banksi, recorded from New England to Florida, whose season covers winterberry (Ilex verticillata) and American holly; the sumac specialist Andrena brevipalpis; the chestnut specialist above; Andrena cornelli on the native azaleas, pinxterbloom azalea (Rhododendron periclymenoides) among them, and rosebay rhododendron; and specialists on mountain laurel and maleberry (Lyonia ligustrina). Willow, blueberry, dogwood, holly and sumac between them account for most of the specialists a woody planting can support.

Honey plants, and what the honey trait means in our catalog

Honey bees are not native, but a plant that yields a honey surplus is producing nectar in bulk, and native bees drink from the same flowers. In our catalog the honey trait marks the plants beekeepers count on: American basswood, black locust, sourwood, black gum, American persimmon and sweet pepperbush. Basswood makes what the Forest Service calls choice honey. Black locust is planted for honey production on three continents, and Hungarian selections have raised its nectar yield 74 percent. Sourwood honey is sold under its own name where the tree is common. The famous tupelo honey comes from Ogeechee tupelo (Nyssa ogeche) along the Apalachicola River in Florida, but black gum is a good honey tree in its own right. The Forest Service silvics also rate persimmon, redbud, silverbell, holly and tuliptree as honey plants.

Nesting: pithy stems, dead wood and bare ground

The 30 percent of bees that nest above ground want beetle tunnels in dead wood and the soft centers of stems, and the Xerces Society names three native shrubs for the job: elderberry, sumac and raspberry. Small carpenter bees (Ceratina) hollow last year’s dead canes and nest a few inches from the flowers that feed them; yellow-faced bees (Hylaeus) take narrower stems and leafcutter bees (Megachile) wider ones; mason bees and leafcutters both use the holes that long-horned and jewel beetles leave in a snag or a log. Leave dead stems standing through winter. In spring cut them to stubble of mixed heights, 8 to 24 inches, so the open ends are available; new growth hides the stubble by summer. Leave that stubble through the following spring as well, because the bees that nested in it are still inside. Keep a snag where it threatens nothing, and a log or a stick pile where a snag is not possible.

The 70 percent that nest underground need something most yards have removed: bare or thinly vegetated soil in the sun. Mining bees, cellophane bees and the blueberry bee dig in loose, well-drained ground, and wood chips or landscape fabric lock them out. Mulch only the first foot in from a path, use fallen leaves rather than bark under shrubs, leave patches of bare ground on a sunny bank and do not till. Leaf litter shelters the bumble bee queens as well, and it beats wood chips under a tree anyway.

Pesticides, including the ones already in the plant

Neonicotinoid insecticides are systemic: a plant takes them up and expresses them in every tissue, nectar and pollen included, and home garden products can legally be applied at concentrations as much as 120 times greater than the same chemicals on a farm. What that does to a bee tree was measured in June 2013 in Wilsonville, Oregon, when 55 flowering littleleaf lindens (Tilia cordata) in a parking lot were treated with dinotefuran, 46 sprayed and 9 drenched at the roots. An estimated 45,830 to 107,470 bumble bees from as many as 596 colonies died under them, the largest documented pesticide kill of bumble bees in North America, and Oregon has since prohibited four neonicotinoids on any linden or basswood by any method. Some neonicotinoids stay in flowers at lethal levels for eighteen months after application, so a treated basswood, locust or holly is a trap, not a resource. Ask any nursery, us included, what has been applied to its stock, and never treat a woody plant for aphids or scale while it is in flower or about to be.

Cultivars and doubled flowers

Most native shrubs sold are cultivars, and the question is what the selection cost the bees. A University of Connecticut trial over two summers compared six native shrubs with their cultivars and found no general rule. Sweet pepperbush ‘Hummingbird’ and ‘Ruby Spice’ drew the same insects as the wild plant; purple-leaved ninebark ‘Diabolo’ matched the species for bees; the compact chokeberries drew as many mining bees per flower cluster as the wild plant, only fewer clusters. The failure was wild hydrangea (Hydrangea arborescens) ‘Annabelle’, bred for big heads of sterile flowers: 42 percent of its florets were fertile against 99 percent in the species, and it received one third the bumble bee visits. The authors’ list of traits that can matter: anthers and pistils converted to petals, flower color, flower density and flower size. So avoid doubled flowers, which trade stamens for petals, and be relaxed about leaf color and compact habit. A seed-grown plant is the species by definition. The invasive ornamentals count for less than nothing, because they take the ground.

Our plants for bees, ranked

1. American basswood: the largest nectar flow in the eastern woods, two weeks in June.
2. Black locust: a fast honey tree for poor dry ground.
3. Sourwood: the honey tree of July, in a size that fits a yard.
4. Eastern redbud: April pollen and nectar for half a dozen bee groups, the blueberry bee among them.
5. Downy serviceberry and Allegheny serviceberry: a week of April flowers for mining bees, then fruit for birds.
6. Black huckleberry: a low heath for dry acid ground that shares a blueberry specialist.
7. American holly and winterberry: holly specialists, honey and a screen.
8. Sweet pepperbush: the bumble bee shrub of July and August.
9. Staghorn sumac and black elderberry: June nectar, then the best nesting stems on the list.
10. Silky dogwood: the shrub dogwood the four dogwood specialists want.
11. American plum and beach plum: thicket plums for April.
12. Allegheny chinquapin: June pollen and a specialist mining bee of its own.
13. Rosebay rhododendron and mountain laurel: bumble bee shrubs for shade, each with a specialist.

The other list matters as much. The willows, which we do not grow, mean more to specialist bees than anything above, and the shrubby ones fit a wet corner. Red maple, black cherry, tuliptree, buttonbush and devil’s walking stick (Aralia spinosa) each fill a slot our catalog does not, and a bee garden should have them from wherever it can get them. Three plants this research turned up are in the catalog now: New Jersey tea (Ceanothus americanus), a June shrub of dry ground with two rare pollen-specialist mining bees of its own; deerberry (Vaccinium stamineum), a blueberry of dry woods with specialists tied to its section of the genus; and pinxterbloom azalea, the April azalea Andrena cornelli depends on.

How to plant for bees

• Cover every month from March to October with at least one woody plant in flower, and preferably three: willow or red maple, serviceberry, redbud, plum, holly, basswood, sumac, sourwood, pepperbush, then asters and goldenrods.
• Plant each species in a group, not a scatter; a clump is found faster and worked longer.
• Leave dead stems through winter, cut them to 8 to 24 inches in spring and leave the stubble a second year; keep a snag, a log or a stick pile.
• Leave bare soil on a sunny bank, keep wood chips to paths and put the leaves under the shrubs instead.
• Put no systemic insecticide on anything that flowers, buy plants that have never had one and choose single flowers over doubled ones.
• Pull the invasive shrubs first; they hold ground that willow, plum and sumac would fill for free.

Sources

• Pollen Specialist Bees of the Eastern United States: Jarrod Fowler and Sam Droege (2020): the 200 eastern pollen specialists, the 14 willow and 10 blueberry specialists, the dogwood, holly, sumac, chestnut, azalea, laurel and maleberry specialists with their states and flight months, and that nearly 60 percent are rare.
• Specialist bees of the Northeast: host plants and habitat conservation: Fowler, Northeastern Naturalist 23 (2016): 61 specialist bee species tied to 33 plant genera in the Northeast.
• Bee Pollination: USDA Forest Service: over 4,000 native bee species in the United States, the honey bee as an import, and nesting in bare ground and old beetle burrows.
• Nesting and Overwintering Habitat for Pollinators and Other Beneficial Insects: Xerces Society (Foltz Jordan, Hopwood and Morris, 2020): 70 percent of native bees nest in the ground, elderberry, sumac and raspberry as nesting stems, cutting stems to 8 to 24 inches and leaving them a second year, snags, mulch and bumble bee queens under leaf litter.
• Neonicotinoids in Your Garden: Xerces Society, Wings (Fall 2012): systemic insecticides reach nectar and pollen, home garden products applied at up to 120 times farm concentrations, lethal levels in flowers eighteen months after application, and asking the nursery what was applied.
• Silvics of North America, Volume 2: Hardwoods: USDA Forest Service: bloom dates, pollinators and honey value for basswood, black locust, sourwood, black tupelo, tuliptree, redbud, silverbell, American holly, persimmon, red maple, black cherry and black willow.
• Seasonal variation of pollen collected by honey bees (Apis mellifera) in developed areas across four regions in the United States: Lau and others, PLOS ONE (2019): the share of spring pollen from trees and shrubs in Michigan, Texas and Florida, oak among the main pollen types, and maple, willow, plum, locust, chestnut and sumac pollen in Michigan colonies.
• Trees for bees: Donkersley, Agriculture, Ecosystems and Environment 270 to 271 (2019): trees as more efficient forage because of their resource density, and the honey bee preference for trees.
• Comparing Insect Pollinator Visitation for Six Native Shrub Species and Their Cultivars: Ricker, Lubell and Brand, HortScience 54 (2019): the Connecticut cultivar trial, sweet pepperbush and ninebark cultivars, ‘Annabelle’ with 42 percent fertile florets and a third of the bumble bee visits, and the traits that reduce visitation.
• Neonicotinoid Pesticides Cause Mass Fatalities of Native Bumble Bees: A Case Study From Wilsonville, Oregon, United States: Hatfield and others, Environmental Entomology 50 (2021): the 2013 linden kill, 45,830 to 107,470 bumble bees from up to 596 colonies, 46 sprayed and 9 drenched trees, and Oregon’s rule on Tilia.
• Selecting Trees and Shrubs as Resources for Pollinators: University of Georgia Extension Bulletin 1483 (2023): which bee genera visit red maple, serviceberry, redbud, plum, viburnum, sumac, pussy willow, sourwood, catalpa and buttonbush, and leafcutter bees using redbud leaves.
• Southeastern Blueberry Bee: Native Blueberry Pollinator: University of Georgia Extension Bulletin 1591 (2026): the blueberry bee’s three to five week adult life, buzz pollination, 50,000 flowers and 6,000 berries per female, ground nesting, and its use of redbud, plum, viburnum, azalea and oak.
• Native Shrubs for Pollinators: Penn State Extension: pussy willow as the earliest bloomer and food for queen bumble bees, spicebush as early nectar for small bees and flies, summersweet, buttonbush and the bees, flies and moths on witch hazel.
• Salix discolor, Fire Effects Information System: USDA Forest Service (Gucker 2007): willows as the first and most important bee forage, 270 flowers in a male pussy willow catkin, the Maine catkin nectar and sugar figures, March to May flowering, and willow seed viable for only days.