Cold hardiness

Future

2050

2100

These values are location-based: this location's current hardiness is the baseline, and the 2050 value is a projected future climate for this same location.

Now

Zone 6b

USDA

Published baseline for this location from 1991-2020.

Source: USDA Plant Hardiness Zone Map 2023 (1991-2020 climatology) via ArcGIS FeatureServer

Won't grow here

2050

Zone 7a

Plotwright

Projected zone for this same location in 2050 (2041-2070) using SSP3-7.0 (regional rivalry).

Won't grow here

In plain terms: This location is in Zone 6b today. Its hardiness profile is cold winters, and coldest nights are typically around -3°F. By 2050, the projected hardiness zone is Zone 7a based on SSP3-7.0 (regional rivalry). That is a +0.5-zone shift from Zone 6b to Zone 7a by 2050.

✕

Out of range today and still out of range in 2050.

Heat tolerance

Future

2050

2100

Heat tolerance values are location-based too: heat days today are observed at this site, and the 2050 value projects this same location under a future climate.

Loading AHS heat-zone data for this location...

Where this plant fits

Suitable across 17 ecoregions — 11 climate-resilient through 2070 · 6 newly possible by 2070. Best matches first.

Atlantic coastal pine barrens

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California coastal sage and chaparral

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Central Pacific Northwest coastal forests

Eastern Australian temperate forests

New Zealand North Island temperate forests

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Northern Pacific Alaskan coastal forests

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What it needs

Conditions

Light

Full sun / Part shade

Water

Moderate water

Spacing

10"

Habit

Mounding to spreading tender perennial grown as a warm-season annual

Care tips

•

Wait for warm soil — set out transplants well after the last frost; cold, wet ground stunts or kills it.

•

Drainage is everything: plant in well-drained sandy loam and water at the base, never overhead.

•

No deadheading needed; it blooms June to frost on its own and tolerates drought and heat once established.

Lifecycle

Planting

In USDA Zones 10-11 grows as a woody-based tender perennial; everywhere colder it is grown as a warm-season annual bedding plant. Set out transplants in spring only after the last frost date, in well-drained sandy loam in full sun to part shade. It thrives in hot, humid summer weather and resents cold, wet soil.

Transplanting

Plant out hardened-off starts after the last frost on an overcast day or in late afternoon. It is sensitive to cold, soggy soil — wait until both air and soil have warmed.

Early growth

Keep evenly moist but avoid overhead watering, which encourages disease. Superior soil drainage is the key to growing it well; it is slow to establish until summer heat sets in.

Maturity

Mature plants mound 6-18 inches (occasionally to 24 inches) tall and about as wide, blooming continuously from June to frost. Low maintenance with no deadheading required.

Propagation

Start seed indoors 12-16 weeks before the last frost date, then set out after frost. Cuttings taken in late summer can be overwintered indoors to hold stock for the following spring. May self-seed in optimum conditions.

Pollination

Self-fertile

The flowers are self-compatible and readily set seed; in good conditions the plant can self-sow. NC State Extension lists the flowers as attracting butterflies and pollinators — the long, narrow corolla tube is suited to long-tongued visitors such as butterflies and moths rather than short-tongued bees.

Plants don't grow alone

Nectar forage

Butterfly

Eastern tiger swallowtail (Papilio glaucus)

NC State Extension lists the flowers as attracting butterflies. The long, narrow nectar tube favors long-tongued butterflies such as swallowtails; mapped here as a representative documented butterfly visitor rather than a recorded specialist relationship.

For people

Toxic — do not consume

Every part of annual vinca is poisonous. NC State Extension lists the flowers, fruits, leaves, roots, seeds, and stems as toxic (severity rated Low), with symptoms from eating large quantities including vomiting, diarrhea, low blood pressure, hallucinations, depression, tremors, seizures, coma, and death. The toxic compounds are the vinca alkaloids — the same class refined from this species into the chemotherapy drugs vincristine and vinblastine. NC State flags it as poisonous to humans and a problem for cats, dogs, and horses.

Toxic parts

flowers, fruits, leaves, roots, seeds, stems

Pet toxicity

NC State Extension lists Catharanthus roseus as a problem for cats, dogs, and horses. The vinca alkaloids it contains can cause vomiting, diarrhea, low blood pressure, tremors, and seizures.

Native range

AHS heat range

9-12

Climate notes

•

Missouri Botanical Garden PlantFinder lists Catharanthus roseus as winter hardy only in USDA Zones 10-11 (where it grows as a woody perennial); across the rest of North America it is grown as a warm-season annual. PlantFinder gives the bloom window as June to frost in full sun to part shade with medium water.

•

Missouri Botanical Garden PlantFinder notes it thrives in hot, humid summer weather and rates it tolerant of rabbits, drought, and dry soil; superior soil drainage is the single most important growing factor.

•

NC State Extension Gardener Plant Toolbox lists the same USDA hardiness zones (10a-11b) and rates the toxicity severity as Low, but flags all parts as poisonous to humans and a problem for cats, dogs, and horses.

•

Tolerates hot to extreme summer heat — a tropical Madagascar native that needs the heat of Hot- and Extreme-tier summers to perform and only persists year-round in the warmest US zones (10-11); elsewhere it is a single-season annual.

In the designer

Growth over time

3-9" tall · 3-9" spread

Set out as a transplant after frost; slow to start until soil warms.

Design roles: Border · Filler · Container

Seasonal interest

Spring

Summer

Fall

Winter

Filled = the plant has seasonal interest · ▾ now = your current season

Annual vinca

At a glance

Why it matters

Cold hardiness

Heat tolerance

Where this plant fits

What it needs

Lifecycle

Pollination

Plants don't grow alone

For people

Native range

Climate notes

In the designer

Seasonal interest

Sources & citations