Illustration
Sunny Boulevard St. John's Wort
Hypericum kalmianum 'Deppe'
Also called hypericum sunny boulevard
Sunny Boulevard St. John's Wort blooms from July through August.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Sunny Boulevard St. John's Wort
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 4–8. Expect it to reach about 2.5 ft tall and 2.5 ft wide at maturity, in roughly 4 years (a house reading).
No toxicity note is on file for Sunny Boulevard St. John's Wort. That is not a clearance: check its safety for people and pets before planting.
What was checked
Mature height and spread, hardiness zones, sun, water, bloom months and color and the trait tags were checked against named botanical sources for this plant, with what the sources could not settle written down; years to mature size rests on a recorded house rule where no publisher states one, and is marked so; its common name and alternate names have not been checked yet. Each fact above carries its own mark. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Sunny Boulevard St. John's Wort
Plant Sunny Boulevard St. John's Wort in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 6, the middle of its hardy zones 4 to 8, spring means March to May and fall means August or September. Once settled, it blooms from July to August.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Sunny Boulevard St. John's Wort get?
2.5 fttall5 ft 7 inan adult2.5 ftwideSee Sunny Boulevard St. John's Wort in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Sunny Boulevard St. John's Wort
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Sunny Boulevard St. John's Wort about 2.5 ft apart, center to center, so each plant has room to reach its full width.
Add Sunny Boulevard St. John's Wort to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Sunny Boulevard St. John's Wort's height, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity were checked against 10 published sources on September 23, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- NC State Extensioncultivar pageheight, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases, pests and toxicity
- Nature Hills Nurseryheight, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil, diseases and pests
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil and diseases
- Proven Winnersthe introducer's brand; Spring Meadow Nurseryheight, spread, hardiness zones, sun, water, bloom months and color, trait tags, soil and pests
- RHSRoyal Horticultural Societyheight, spread, sun, bloom months and color, trait tags, soil, diseases, pests and toxicity
- The Morton ArboretumKalm's St. John's wort pageheight, spread, hardiness zones, sun, bloom months and color, soil and diseases
- US plant patent (Google Patents)Google Patents USPP20045P2, assigned to Spring Meadow Nurseryheight, spread, hardiness zones, bloom months and color and diseases
- NC State Extensionspecies pagehardiness zones, bloom months and color, pests and toxicity
- Plant Addictsheight, spread, hardiness zones, sun and water
- illinoiswildflowers.infoIllinois Wildflowers (John Hilty)toxicity
How the checking works, and what each standard covers, is on the verified plants page.
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Design a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.