Recently, I saw this listing of woody trees and shrubs that are good pollinators. I grow a number of these great plants in my garden and will vouch for the accuracy of this list. The source is HRI Research and data was collected in the Ohio Valley region of the U.S. (includes Tennessee, Kentucky, southern Indiana and Illinois, and SW Pennsylvania).
Cornelian cherry (Cornus mas)
Dwarf fothergilla (Fothergilla gardenii)
Winter honeysuckle (Lonicera fragrantissima)
Higan weeping cherry (Prunus subhirtella ‘Pendula’)
Higan cherry (Prunus subhirtella ‘Autumnalis’)
Flowering cherry (Prunus spp.)
Flowering crabapple (Malus spp.)
Burkwood viburnum (Viburnum burkwoodii)
Cherry laurel (Prunus laurocerasus)
Red horsechestnut (Aesculus x carnea)
American holly (Ilex opaca)
Foster’s holly (Ilex x attenuata)
Winter king hawthorn (Crataegus viridus)
Serviceberry (Amelanchier spp.)
Eastern redbud (Cercis canadensis)
Black gum (Nyssa sylvatica)
Ninebark (Physocarpus opulifolius)
Fuzzy deutzia (Deutzia scabra)
Firethorn (Pyracantha spp.)
Japanese tree lilac (Syringa reticulata)
American yellowwood (Cladrastis kentukea)
Mock orange (Philadelphus spp.)
Virginia spiraea (Spiraea virginiana)
Wild indigo (Amorpha fruticosa)
Buttonbush (Cephalanthus occidentalis)
Climbing rose (Rosa setigera)
Common winterberry (Ilex verticillata)
Sweetspire (Itea virginica)
Bottlebrush buckeye (Aesculus parviflora)
Linden (Tilia cordata)
Basswood (Tilia americana)
Golden raintree (Koelreuteria reticulata)
St. John’s Wort (Hypericum frondosum)
Devil’s walking stick (Aralia spinosa)
PeeGee hydrangea (Hydrangea paniculata)
Summer sweetshrub (Clethra alnifolia)
Bee bee tree (Tetradium danielii)
Winged sumac (Rhus copallinum)
Crape myrtle (Lagerstroemia spp.)
Glossy abelia (Abelia x grandiflora)
Seven-son flower (Heptacodium miconioides)
Chaste tree (Vitex agnus-castus)
Trees & Shrubs That Attract Few Bees*
Forsythia (Forsythia spp.)
Star magnolia (Magnolia stellata)
European boxwood (Buxus sempervirens)
Sassafras (Sassafras albidum)
Japanese Kwanzan cherry (Prunus ‘Kwanzan’)
Mulan magnolia (Magnolia liliiflora)
White azalea (Azalea spp.)
Koreanspice viburnum (Viburnum carlesii)
Carolina allspice (Calycanthus floridus)
White fringetree (Chionanthus virginicus)
Hybrid tea rose (Rosa spp.)
Smooth hydrangea (Hydrangea arborescens)
Bigleaf hydrangea (Hydrangea macrophylla)
*For more information: GrowWise.org and HRIresearch.org