Illustration
Red Heart
Hibiscus syriacus 'Red Heart'
Red Heart blooms from July through September.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Red Heart
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 5–9. Expect it to reach about 8 ft tall and 6 ft wide at maturity, in roughly 4 years (not yet checked).
No toxicity note is on file for Red Heart. That is not a clearance: check its safety for people and pets before planting.
What this means
Written with AI assistance and not yet checked plant by plant against recorded sources, so treat every fact above as a starting point. Its scientific name was checked against botanical registries, an audit keeps its values consistent with the rest of the library, and a July 2026 review re-read the main facts of every plant then in the library against horticultural authorities without recording a source for each, which is why none of that counts as checked here. The source-by-source check is working through the whole library in the open, and a checked plant says so in this row.
When to plant Red Heart
Plant Red Heart 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 7, the middle of its hardy zones 5 to 9, spring means March to May and fall means September or October. Once settled, it blooms from July to September.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 7, the middle of this plant's hardy range, start with zone 7 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Red Heart get?
8 fttall5 ft 7 inan adult6 ftwideSee Red Heart 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 Red Heart
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Red Heart about 6 ft apart, center to center, so each plant has room to reach its full width.
Add Red Heart to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
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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.