May Showers Bring Summer Flowers: Most gardeners think that spring is the time of year when woody plants flower. However, many trees and shrubs flower from late spring to late summer. Wisconsin homeowners can choose from a variety of plants listed below to insure continual bloom throughout most of the growing season.
* Catalpa speciosa (Northern catalpa): 50-60' tall; large leaves; large, white flowers in late June
* Cladrastis lutea (yellowwood): 30-40' tall; vase-shaped; white, fragrant flowers in mid June
Cornus alternifolia (pagoda dogwood): 15' tall; native; creamy, fragrant flowers in mid June; blue fruit
* Cotinus obovatus (American smoketree): 20-30' tall; greenish, smoky flowers in late June
* Crataegus phaenopyrum (Washington hawthorn): 25' tall; thorny; white flowers in June; red fruit
* Maackia amurensis (amur maackia): 20-30' tall; smooth olive bark; white flowers in July
**Magnolia sieboldii (Oyama magnolia): 15' tall; white, fragrant flowers in late June; may be hard to find
**Stewartia pseudocamellia (Japanese stewartia): 15-20' tall; exfoliating bark; white flowers in July, acid
Syringa reticulata 'Ivory Silk' (Japanese tree lilac): 15-25' tall; oval shape; creamy flowers in mid June
* Syringa pekinense (Pekin lilac): 15-20' tall; exfoliating bark; creamy-white flowers in mid June
Tilia cordata (little leaf linden): 50-60' tall; pyramidal shape; small, fragrant flowers in June
* Aesculus parviflora (bottlebrush buckeye): 8' tall; suckering; showy, white flowers in July
**Buddleja davidii (butterfly bush): 5' tall; dies back; fragrant flowers from July to fall; marginally hardy; needs protection
**Calycanthus floridus (Carolina allspice): 6-8' tall; fragrant, brownish-maroon flowers in mid June; marginally hardy
**Caryopteris x clandonensis (blue mist spirea): 3' tall; dies back; blue flowers in Aug. to Sept.; marginally hardy
* Cephalanthus occidentalis (buttonbush): 8' tall; native shrub; coarse texture; creamy-white, globular flowers in July
* Clethra alnifolia (summersweet clethra): 4-8' tall; fragrant, pinkish flowers in late July to Aug.; acid soil
Cornus alba (Tatarian dogwood): 6-8' tall; red stems; white, flat-topped flowers in June
Cornus racemosa (gray dogwood): 6-10' tall; native; white, flat-topped flowers in June; white fruit
Cornus stolonifera (redosier dogwood): 6-8' tall; native; red stems; white, flat-topped flowers in June
* Cotinus coggygria (smokebush):10-15' tall; some with red new growth; pinkish, smoky flowers in July
Diervilla lonicera (bush honeysuckle): 3' tall; native; suckering; small, yellow flowers in early July
* Genista tinctoria (common woodwaxen): 2-3' tall; bright, yellow flowers in late June to July
** Hibiscus syriacus (rose-of-Sharon): 8' tall; large flowers in July to Aug.; marginally hardy; dies back
Hydrangea arborescens 'Annabelle' (Annabelle hydrangea): 4' tall; suckering; large, white flowers in July
Hydrangea macrophylla 'All Summer Beauty' (bigleaf hydrangea): 4' tall; large, pink flowers in July-Aug.
Hydrangea paniculata (panicle hydrangea): 6-15' tall; large, white flowers Aug. to Sept. that turn brown
* Hypericum kalmianum (Kalm St. Johnswort): 2-3' tall; native; showy bark; yellow flowers in July to Aug.
* Lespedeza bicolor (shrub bushclover): 4' tall; dieback shrub; reddish-purple flowers in July-Aug.
* Ligustrum obtusifolium var. regelianum (Regel's border privet): 4' tall; hedge; white flowers in late June
**Perovskia atriplicifolia (Russian-sage): 3-4' tall; gray-green leaves; violet-blue flowers in Aug.; dies back
Potentilla fruticosa (potentilla): 3' tall; native; yellow to white flowers from late June to fall
* Rosa hybrids: many to choose from; many colors; choose ones for disease resistance
Rosa rubrifolia (redleaf rose): 4-6' tall; suckering; red-purple leaves; pink flowers in June; red hips
Rosa rugosa (rugosa rose): 4-5' tall; fragrant flowers in many colors from late June to fall; large hips
* Rosa setigera (prairie rose): 6' tall; native; suckering; pale pink flowers in early July; small hips
* Rosa pimpinellifolia (Scotch rose): 3-4' tall; suckering; yellow, white, or pink flowers in June to July
Rosa virginiana (Virginia rose): 4' tall; suckering; red stems; pink flowers in June; red hips
Sambucus canadensis (American elderberry): 8' tall; native; suckering; white flowers in June; black fruit
Sorbaria sorbifolia (Ural falsespirea): 5' tall; suckering; large, fuzzy, white flowers in July
Spiraea x billiardii (Billiard spirea): 6' tall; suckering; large, dense, rose flowers in July to Aug.
Spiraea fritschiana (Korean spirea): 4' tall; blue-green leaves; large, white flowers in late June
Spiraea japonica (Japanese spirea): 2-4' tall; many cultivars, white or pink flowers in June to Aug.
Tamarix ramosissima (tamarisk): 8' tall; fine texture; pink flowers in late June to Aug.
**Vitex agnus-castus (chastetree): 3-5' tall; dies back; blue flowers in late July to Aug.; marginally hardy
* Weigela x ‘Red Prince’ (Red Prince weigela): 5' tall; red flowers in late May and again in summer
* Yucca filamentosa (yucca): 2-3' tall; evergreen; sword-like leaves; large white flowers in July
Flowering and Colorful Foliage Vines:
* Actinidia kolomikta (kolomikta actinidia): grown mainly for foliage with white to pink mottling
* Actinidia polygama (silvervine actinidia): grown mainly for foliage with silvery mottling
* Aristolochia macrophylla (Dutchman's pipe): grown mainly for large leaves; small, pipe shaped flowers
* Campsis radicans (trumpet creeper): vigorous; fast growing; large, orange flowers from July-Aug.
* Clematis hybrids: many colors and sizes of flowers, early to late summer; some with showy seed heads
**Clematis tangutica (golden clematis): yellow, bell-shaped flowers in late summer; showy seedheads
* Clematis terniflora (sweet autumn clematis): very showy, fragrant, white flowers in early Sept.
* Clematis texensis (scarlet clematis): urn-shaped, nodding, scarlet to pink flowers in late June to fall
* Clematis viticella (Italian clematis): white, violet, red, or mauve flowers in midsummer
* Hydrangea petiolaris (climbing hydrangea): large, lacy, white flowers in late June; exfoliating bark
* Lonicera x brownii 'Dropmore Scarlet' (Dropmore scarlet honeysuckle): summer, tubular, scarlet flowers
* Lonicera x heckrottii (goldflame honeysuckle): dark pink and yellow, tubular, fragrant, summer flowers
* Lonicera sempervirens (trumpet honeysuckle): trumpet shaped, orange-scarlet or yellow flowers in July
* Polygonum aubertii (silver fleece vine): fragrant, white, lacy flowers in summer; fast grower, marginal
* Rosa x 'Henry Kelsey' (Henry Kelsey rose): climbing; arching; semi-double, red flowers in summer
* Rosa x 'William Baffin' (William Baffin rose): climbing; semi-double, deep-pink flowers in summer
**Wisteria frutescens (American wisteria): fragrant, lilac or white, 6" long flowers in July; marginally hardy
*Wisteria macrostachys (Kentucky wisteria): lavender or white, 8" long flowers in June
No asterisk indicates cold hardy to zone 3.
* Indicates hardy to zone 4. In colder areas, such as zone 3 (northern WI), the plant may die back.
**Indicates hardy to zone 5. In colder areas, such as zone 3 and 4 (central WI), the plant will die back.
For more information on woody plants:
See UW-Extension bulletins A2865, A3067, G1609, A1771, and University of Wisconsin Garden Facts X1012, X1014, X1015, or contact your County Extension Agent.