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Crocanthemum, Genus, spp., Multiple species,

Genus
Multiple species

frostweeds

Cistaceae Americas (mainly North America)

Attracts Pollinators Attracts Butterflies Drought Tolerant Container Friendly

SunFull Sun

WaterLow · drought-tolerant

HardinessZones 5–9

Overview

Crocanthemum is a genus of about 20 low perennials and subshrubs in the rock-rose family, Cistaceae, native to the Americas and segregated from the Old World Helianthemum. Plants are small and often woody at the base, 4–12 inches (10–30 cm) tall, forming spreading clumps of slender stems set with narrow, hairy, grey-green leaves. The five-petaled flowers are yellow and about 0.5–1 inch (12–25 mm) across, opening in sun and shedding their petals by day's end, with later flowers of the season often smaller and self-pollinating without opening. The common name frostweed comes from the curls of ice that form as sap splits the lower stems on cold autumn mornings. Crocanthemum grows on dry, sandy, and rocky ground in open woods, barrens, and grassland, and it depends on lean, sharply drained soil and full sun. It is short-lived and resents rich, damp ground, but it suits sunny banks, sandy beds, and rock gardens. Many species host specialized soil fungi and feed butterfly larvae.

Native Range

Crocanthemum is native to the Americas, with most species in eastern and central North America and others in the west and into South America. It grows in sandy barrens, pine and oak woodland, prairies, and rocky open ground.

Suggested Uses

Crocanthemum is used in rock gardens, sandy and gravel beds, dry banks, and native-plant and pollinator gardens. It is planted in groups for a low summer show of yellow, spaced 8–12 inches (20–30 cm) apart. It also suits restoration of sandy barrens and prairie, where it supports specialized bees and butterflies.

How to Identify

Identify Crocanthemum by its low, wiry, semi-woody stems and small, narrow, grey-hairy leaves, topped in summer by yellow five-petaled flowers that drop their petals within a day. Two flower types occur: open spring flowers and smaller closed flowers later in the year. Ice ribbons at the stem base on frosty mornings are a further sign.

Appearance

Size & Dimensions

Height4" - 1'

Width/Spread8" - 1'4"

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Flowers: May–July

Spring Summer

Crocanthemum flowers in late spring and summer, roughly May to July, opening yellow flowers in the morning sun that shed their petals by afternoon. A second wave of small, closed, self-fertile flowers follows later in the season. Each open flower is brief, but a clump produces them over several weeks.

Detailed Descriptions

Foliage Description

grey-green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0 (Acidic to neutral)

3579

Soil Types

sand rocky

Drainagewell drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Crocanthemum grows in full sun and lean, dry, sharply drained sandy or rocky soil at a pH of 5.5–7.0. Established plants are drought-tolerant and decline in rich, moist, or heavy ground, which causes root rot and rank growth. The genus is hardy in its native range, with many species taking cold to about −20°F (−29°C). It needs no feeding, as rich soil shortens its life. Plants are short-lived and resent transplanting, so they are raised from seed sown where they are to grow. Few pests trouble them in a hot, open site.

Pruning

Crocanthemum needs little pruning beyond a light trim after the main flush to keep a compact shape. Cutting back hard into old wood is avoided, as the semi-woody stems regrow slowly. Leaving some late flowers to set seed maintains a colony, since plants are short-lived.