Narthecium spp.

bog asphodel

Nartheciaceae

Cool temperate Northern Hemisphere (Europe, eastern and western North America)

Attracts Pollinators

Native to North America

SunFull Sun – Part Shade

WaterHigh

HardinessZones 3–8

Overview

Narthecium spp. is a genus of about eight rhizomatous perennials in the family Nartheciaceae, found in acidic bogs, wet heaths, and seepage slopes across the cool temperate Northern Hemisphere. Plants grow from creeping rhizomes and reach 10-45 cm (4-18 in) tall in flower, forming colonies of flattened, iris-like fans of narrow leaves 5-30 cm (2-12 in) long. In summer each fertile shoot carries an erect raceme of star-shaped yellow flowers, each 6-12 mm (0.2-0.5 in) across with six narrow tepals and woolly orange-yellow filaments behind the stamens. As the flowers fade the whole spike turns deep orange and holds upright capsules that persist into autumn. The foliage colours yellow to orange before dying back for winter. Species include N. ossifragum of western Europe, N. americanum of the New Jersey pine barrens, and N. californicum of the Pacific states. All grow only where the ground stays wet and acidic, and they decline quickly if the soil dries or is limed. N. ossifragum has a longstanding link to bone-softening and photosensitisation in grazing livestock.

Native Range

Narthecium spp. occurs across cool temperate parts of the Northern Hemisphere. N. ossifragum ranges through western and northern Europe, N. americanum is restricted to the New Jersey pine barrens and a few nearby sites, and N. californicum grows in mountain seeps of California and Oregon. All are confined to acidic, permanently moist ground.

Suggested Uses

Grown in bog gardens, at acidic pond and stream margins, and in peat beds, spaced 20-30 cm (8-12 in) apart to form colonies. The summer flowers and orange seed spikes give an extended season of interest in consistently wet ground.

How to Identify

Look for flattened fans of narrow, iris-like leaves rising from a creeping rhizome in wet, acid ground. Summer brings erect spikes of six-tepalled yellow stars with markedly woolly orange filaments. After flowering, the spike and seed capsules turn rich orange, a colour change that marks Narthecium spp. through late summer.

Appearance

Size & Dimensions

Height4" - 1'6"

Width/Spread6" - 1'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~3 weeks

Summer

Flowering occurs in summer, generally July and August. Each spike opens its yellow star-shaped flowers from the base upward over two to four weeks. The faded spike then turns orange and carries upright capsules into autumn.

Detailed Descriptions

Foliage Description

Green, turning yellow-orange in autumn

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-8 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 Range4.0 - 5.5(Acidic)

357912

Soil Types

peat sand

Drainagewet

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Narthecium spp. needs permanently moist to wet, acidic soil of low fertility, such as peat or sandy peat with a pH near 4.0 to 5.5. It grows in full sun to part shade and suits bog gardens, pond margins, and other sites that never dry out. The genus is hardy across roughly USDA zones 3 to 8, depending on species. It fails on alkaline or free-draining ground and cannot tolerate lime or fertiliser. Rainwater rather than hard tap water keeps the root zone acidic in cultivation. Established colonies spread slowly by rhizome.

Pruning

The orange seed spikes are left standing for autumn interest, then old foliage and stems are cut back as they collapse in late autumn. Congested rhizome colonies can be divided in spring where more plants are wanted. No other routine pruning is required.