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Calopogon tuberosus

tuberous grasspink

Orchidaceae Eastern North America

Attracts Pollinators Container Friendly

Native to North America

SunFull Sun – Part Shade

WaterHigh

HardinessZones 3–9

Overview

Calopogon tuberosus is a terrestrial orchid of eastern North American wetlands, growing from an underground corm. A single grass-like leaf 8-20 inches (20-50 cm) long rises from the base, and a slender flowering stalk 1-4 feet (30-120 cm) tall carries a loose raceme of 2-15 flowers in early to mid summer. Each flower is about 1-1.5 inches (2.5-4 cm) across and pink to magenta, opening from the bottom of the spike upward. Unlike most orchids, the flower is held with the lip uppermost, and that lip bears a crest of yellow, club-tipped hairs that mimic pollen-bearing stamens. Bees land on the false anthers expecting pollen, the hinged lip tips them onto the column, and pollen is transferred, though the flower gives no actual reward. It grows in acidic bogs, wet meadows, fens, and pine savannas from Canada south through the eastern United States, in soils that stay wet and sunlit. It requires constant moisture, acidic peaty soil, and open sun, and it declines under shade or drying. Foliage dies back in autumn, and the corm overwinters dormant. In cultivation it persists where constant bog conditions are maintained.

Native Range

Calopogon tuberosus is native to eastern North America, from Newfoundland and the Great Lakes south to Florida and Texas, and into the Caribbean. It grows in acidic bogs, fens, wet meadows, and pine savannas that stay moist and sunny.

Suggested Uses

Calopogon tuberosus is used in bog gardens, container bogs, and constantly wet pond margins alongside other acid-loving wetland plants. It is planted 6-12 inches (15-30 cm) apart in groups. It suits only permanently wet, sunny, acidic sites.

How to Identify

Look for a single narrow, grass-like leaf at the base and a slender stalk 1-4 feet (30-120 cm) tall bearing 2-15 pink to magenta flowers in summer. Each flower is held with the lip uppermost, carrying a crest of yellow, club-tipped hairs, unlike the lip-down arrangement of most orchids. The wetland habitat, grassy single leaf, and lip-up pink flowers separate it from other native bog orchids.

Appearance

Size & Dimensions

Height1' - 4'

Width/Spread6" - 1'

Reaches mature size in approximately 4 years

Colors

Flower Colors

pink

purple

Foliage Colors

green

Bloom Information

Bloom Period

~4 weeks

Spring Summer

Pink to magenta flowers open in early to mid summer, roughly May to August depending on latitude. Each spike opens its 2-15 flowers in sequence from the bottom up over about four weeks. Bloom depends on full sun and constantly moist soil.

Detailed Descriptions

Flower Description

Pink to magenta

Foliage Description

Green

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 6-10 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 Range4.5 - 6.5(Acidic)

357912

Soil Types

peat sand

Drainagewet

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

2-4 years

Care & Maintenance

Care Guide

Calopogon tuberosus grows in constantly wet, acidic, peaty or sandy soil in full sun to light shade, in bog gardens, container bogs, and the wet margins of ponds. It needs year-round moisture and acidic conditions and declines in shade, drought, or alkaline soil. It is grown in a peat-and-sand mix kept saturated, often in a pot standing in a tray of water. No standard fertilizer is used, as the roots are sensitive to mineral salts. Foliage dies back in autumn, and the dormant corm is kept cool and moist through winter. It is hardy across USDA zones 3-9 where bog conditions are maintained.

Pruning

Calopogon tuberosus needs no pruning. The spent flowering stalk can be cut after bloom, and the yellowing leaf left until it dies back naturally in autumn. The dormant corm is left undisturbed in its wet medium over winter.