Students for Stewardship The Cork Board
← Back to the library

'Deppe' Sunny Boulevard® St. John's Wort

Hypericum kalmianum (hy-PEER-ih-kum kal-mee-AY-num)

Family: Hypericaceae Native Shrub (3-15 ft)

'Deppe' Sunny Boulevard® St. John's Wort is a cultivar deciduous shrub with showy yellow flowers and a long bloom season.Deppe' is sold under the trade name SUNNY BOULEVARD and is the product of an open pollination of H. kalmianum 'Gemo' (seed parent) and an unknown selection of H. kalmianum (pollen parent) that occurred in a controlled breeding program in Grand Haven, Michigan in 2002. It is distinguished by its compact-mounding form, dark green leaves, bright yellow flowers and free-flowering habit. SUNNY BOULEVARD typically grows to 2 to 3 feet tall. U.S. Plant Patent PP20,045 was issued on June 2, 2009. Hypericum kalmianum, (Kalm's St. John's Wort) the parent plant, is a perennial, herbaceous, deciduous or evergreen shrub or small tree that, at maturity, can reach a height of 3 feet. It is drought tolerant and more loose and open in form than other of the more than 400 species of hypericum. It is also the most cold-hardy of the hypericum. Kalm's St. John's Wort is a flowering shrub with numerous 1 inch yellow flowers over a month long blooming period in mid to late summer. It also has a woody root system that is shallow and spreading. Prune if needed after bloom in late summer. Genus name comes from the Greek words hyper meaning above and eikon meaning picture in reference to the practice of hanging flowers from this genus above images, pictures or windows. The species name honors Peter Kalm, a student of Linnaeus, who reportedly discovered this plant in the wild in North America in the mid-1700s. Grow this cultivar in a container, mass plant in a shrub border or use as a low hedge. The plant prefers full sun, wet to moist conditions, and well-drained soil containing calcareous sand or limestone. Shallow water is tolerated if it is temporary. It also tolerates a range of soil types, drought, and dry soil. The leaves of this St. John's Wort species are toxic to domesticated farm animals, particularly those with white or thin fur because these plants contain a toxin that increases sensitivity to sunlight, causing irritation of the skin. Consumption of these plant species can also irritate the gastrointestinal tract of these animals. Diseases, Insect Pests, and Other Plant Problems : No known diseases or insect pests. More information on Hypericum kalmianum .

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 60 attributes.

How it fits the guild

Guild layer 3 - Shrub (3-15 ft)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Fills a similar niche Hibiscus syriacus 'Blue Bird' Spiraea japonica Limemound® 'Monhub' Tecoma stans

Full plant profile

Growing Conditions
Plant type
Perennial; Shrub
Life cycle
Perennial; Woody
USDA zones
4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
Light
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Sand
Soil drainage
Good Drainage | Moist | Occasionally Dry | Occasionally Wet
Available space
3 feet-6 feet
Mature size
Height: 2 ft. 0 in. - 3 ft. 0 in. | Width: 3 ft. 0 in. - 4 ft. 0 in.
Growth rate
Slow
Maintenance
Low
Canopy layer
3 - Shrub (3-15 ft)
Form & Appearance
Habit / form
Dense; Erect; Mounding; Multi-stemmed
Texture
Medium
Foliage
Broadleaf Evergreen; Deciduous
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Opposite; Whorled
Leaf shape
Linear; Oblanceolate; Oblong
Leaf margin
Entire
Leaf size
1-3 inches long, < 1 inch wide
Hairs present
No
Leaf detail
Pairs of opposite primary leaves occur along the young stems. There are often clusters of smaller secondary leaves near the axils of the opposite primary leaves. The dark green leaves are up to 2 inches long and 1/3 of an inch across; they are linear-oblong to oblanceolate in shape and their margins are entire (toothless) and revolute (rolled downward). The upper leaf surface is glabrous, and sometimes glaucous, while the lower leaf surface is glabrous, and sometimes glaucous. All leaves are sessile or nearly so.
Flower color
Gold/Yellow
Flower value
Long Bloom Season; Showy
Flower form
Corymb
Flower size
1-3 inches
Flower detail
Bright yellow flowers appear on new wood. Upper stems terminate in corymbs or compound corymbs of 3 to 7 flowers. Solitary or cymose, terminal or axillary. Yellow (usually) 5-petaled (rarely 4), 5 sepals (rarely 4); stamens numerous, in bundles or in showy boss.
Bloom time
Summer
Fruit color
Brown/Copper
Fruit type
Capsule
Fruit value
Showy
Fruit size
< 1 inch long
Fruit detail
Flowers are replaced by seed capsules about 1/3 of an inch long that are lanceoloid in shape and 5-lobed. The interior of each seed capsule has 5 completely separated cells; there are numerous seeds in each cell. These seeds are dark-colored, narrowly oblongoid, and somewhat flattened.
Bark color
Light Brown; Red/Burgundy
Bark detail
Branches near the base of this shrub have yellowish brown to reddish brown papery bark that often becomes shredded into white strips or narrow sheets.
Stem color
Green
Stem detail
Young stems are light green, glabrous, and 4-angled. Contains 2 to 4 (up to 6) ridges on newer growth, smooth and rounded on older growth.
Wildlife & Ecology
Native status
Native
Origin
Northeastern United States and Canada
Distribution
DC , IL , IN , MI , NY , OH , WI
Attracts
Bees
Food & Medicine
Harvest time
Fall
Fruit type
Capsule

Edibility

Toxic to livestock.

Landscape Use
Landscape location
Container
Landscape theme
Pollinator Garden; Winter Garden
Design feature
Border; Hedge; Mass Planting; Small groups
Garden tags
#nectar plant summer #long bloom time #showy flowers #flowers early summer #flowers mid-summer #low maintenance #yellow flowers #flowers late summer #salt tolerant #mass planting #deer resistant #bee friendly #container plant #hedge #wildlife friendly #shrub border #small groups
Problems & Resistance
Problems
Problem for Horses
Resistant to
Deer; Drought; Salt
Propagation
Division; Root Cutting

Planted at Hunnicutt

Nobody’s planted this one yet.