Summersweet
Clethra alnifolia
Family Clethraceae
Summersweet does two things almost no shrub can: it blooms in real shade, and it blooms in August, throwing spires of intensely fragrant flowers just when the garden runs out of steam. The perfume carries across a yard, and butterflies and bees arrive from everywhere to work it.
A native hardy from zone 3 to 9, it takes wet feet, shrugs off deer, and stays a manageable 4 to 8 feet. Underused is the polite word; a pollinator lifeline in the late-summer lull is the accurate one. Tuck it in the shady, damp corner you had written off and let August surprise you.
Full Sun to SHADE
Moderate water
Slow-Moderate growth
Deer-resistant
Native to North America
Attracts butterflies
Attracts bees
From the print shop
Growing summersweet? Hang it.
Our Plant Library collection carries summersweet — Clethra alnifolia, print Nº 117, “Summersweet.”
526 designsfrom $12.99white or black backgroundmatte poster, unframed
Will it thrive where you are?
Enter your ZIP — we look up your USDA hardiness zone (2023 map) and check it against what summersweet actually needs.
Hardy inZones 3-9Summersweet · Common problems
Common summersweet problems
Pests
1 problem on file
- Almost none
Diseases
1 problem on file
- Almost none
Summersweet · Growing & propagation
Growing summersweet
- Light
- Full Sun to SHADE
Rare bloomer for shade
- Water
- Moderate-High
Wet-tolerant
Soil- Acid, moist, humusy · pH 5.0 - 6.5
Fertilizer- None needed
Pruning- Early spring (blooms on new wood)
Renewal-prune suckers; cut back in spring for density.
Spacing- 4-5 ft
How to plant & propagate summersweet
- Propagate
- Seed (stratify), cuttings, or layering
Summersweet · Calculators & field guides
A little help in the garden.
Summersweet · Yearly calendar
The summersweet year, month by month
Jan
No calendar activity is listed for this month.
BloomPruneBloomJuly to August
PruneMarch to April
What each band means
- Bloom — flowers open — pollinators working, frost on blossoms is the danger.
- Prune — shape it now — cuts heal cleanly and structure is visible.
These are the species' typical months — expect them a few weeks earlier in warm zones and later in cold ones. Watch the plant, not just the calendar.
Summersweet · Ecology & uses
Ecology & uses
Clethra alnifolia
Summersweet in the garden system
- Shrub layer shrub
- Nectary/insectary
- Attracts
- Butterflies, Bees
Habitat- Wetland
- Moisture
- Facultative / average
- Deer
- Resistant
A safer unfenced choice
- Origin
- Native to North America
What summersweet is grown for
✓ Not known to be toxic
Use- Shade bloom
- Use
- August pollinators
- Use
- Rain gardens
Edibility, identification, and traditional-use notes here are general reference — not medical or veterinary advice, and not a claim that any plant treats or prevents anything. Medicinal ratings record how strongly a plant features in herbal tradition, nothing more. Never eat or dose a plant you have not positively identified. More on how to use this library.
Summersweet · Varieties & cultivars
Choosing a summersweet variety
'Ruby Spice' (pink, holds color); 'Hummingbird' (compact); 'Sixteen Candles'
Sources & plant identity
Know what you’re growing.
See where the knowledge comes from.
Summersweet
Clethra alnifolia
The plant, at a glance.
- Botanical name
- Clethra alnifolia
- Plant family
- Clethraceae
- Growth habit
- Shrub · Perennial
- Origin
- Native to North America
- USDA plant symbol
- CLAL3
- Invasive risk
- Low
Hardiness, size and timing vary with your cultivar, soil and climate.
Rooted in research.
University extension research, brought together with hands-on growing experience at Story Thyme Farms.
Questions
Summersweet questions, answered straight.
Do deer eat summersweet?
Rarely — summersweet is considered deer-resistant, which makes it one of the safer unfenced choices in deer country. Hungry deer in a hard winter test every rule, but it's a low-risk pick.
Is summersweet safe for kids and pets?
Summersweet is commonly eaten and isn't considered toxic, but "commonly eaten" isn't a guarantee for any particular person or animal — allergies, quantity, and which part you eat all matter. Never eat a plant you haven't positively identified, and check with a vet before letting pets or livestock graze anything new.
How do you propagate summersweet?
Seed (stratify), cuttings, or layering.
Elsewhere
Where summersweet sits in the library.
Rose
Hydrangea
Common Lilac
Forsythia