PL. —Heuchera americanaBotanical illustration — drop image
Heuchera americana

Alum Root

SpringSummer
3a8bHardiness zone
Peak bloom windowZone 6b · frost-offset weeks
Winter
Not in bloom
Spring
Peak bloom
Summer
Not in bloom
Fall
Not in bloom
Peak bloom
In bloom
Background

Heuchera americana is a native evergreen perennial forming low rosettes of lobed, often mottled leaves. It grows naturally on rocky woodland edges, cliff faces, and dry slopes across eastern and central North America. In the garden it functions as a long-lived, low-maintenance foliage plant for shade and part-shade positions, holding its leaves through winter across most of its range.

The crown tends to push upward over time, exposing the woody base. Division every three to four years resets this, restores vigor, and provides propagation material. Heuchera tolerates thin, rocky, or clay-heavy soils better than most perennials, but waterlogged conditions invite crown and root rot. Slightly acidic, humus-amended soil improves foliage color and growth rate. A light layer of shredded leaf mulch applied after the ground cools reduces freeze-thaw heaving without smothering the evergreen rosette.

The common name refers to the alum-like astringency of the root. Native peoples and early American settlers applied root preparations as a poultice for wounds and used them internally for diarrhea and sore throat. Tannins are the primary active component. Wiry stems carrying small greenish-white flowers rise above the foliage in late spring and attract native bees and hummingbirds.

Care guide
SunPart shade to full sun — 3–6 hours daily
Water1 inch per week; keep consistently moist
SoilWell-draining, humus-rich; pH 5.5–7.5
Spacing12–18 inches
Height18–30 inches
Zone3a – 8b
Native RegionAL, AR, CT, DE, DC, GA, IL, IN, IA, KS, KY, ME, MD, MA, MI, MN, MS, MO, NE, NH, NJ, NY, NC, OH, OK, PA, RI, SC, SD, TN, TX, VT, VA, WV, WI
Frost hardy
Seasonal tasks
spring
cutRemove tattered or winter-burned foliage before new leaves expand in early spring.
watchCheck crowns for frost heaving; press or replant any crown lifted above soil level before growth resumes.
sowDivide woody or congested crowns; replant divisions with the crown set exactly at grade, not proud of the soil surface.
summer
watchInspect leaf undersides for spider mites during hot, dry spells; dislodge with a strong water spray and repeat every few days.
watchLook for angular brown spots between leaf veins, a sign of foliar nematodes. Remove and destroy affected leaves; eliminate overhead irrigation.
fall
sowPlant container-grown specimens at least six weeks before first frost to allow root establishment before the ground freezes.
watchApply a light shredded-leaf mulch around crowns after the ground cools to buffer freeze-thaw cycles and reduce heaving.
Common problems

Crown Rot

Symptoms

Lower leaves yellow and wilt; the base of the rosette turns brown and soft, sometimes with white fungal threads at the soil line. Plants collapse in wet conditions.

Treatment

Remove and destroy affected plants. Improve drainage and avoid overhead watering. Do not mulch directly against the crown. Space plants for airflow and avoid replanting in the same wet spot.

Powdery mildew

Symptoms

White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.

Treatment

Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.

Phytophthora Root Rot

Symptoms

Wilting despite moist soil, yellowing leaves, stunted growth, and dark, decayed roots and crown tissue. Vines may collapse during hot weather.

Treatment

Plant in well-draining soil and avoid waterlogging. Remove and destroy affected vines. Improve drainage with raised beds or amended soil and avoid overwatering.

Foliar Nematode

Symptoms

Angular brown or black patches on leaves, bounded by leaf veins, starting on lower foliage and moving upward. Affected leaves wither but stay attached.

Treatment

Remove and destroy infected leaves and surrounding debris. Avoid overhead watering and wetting foliage. Space plants for airflow and do not compost affected material. Severely infested plants should be dug out and discarded.

Pests

Spider Mites

Tetranychus urticae
Symptoms

Fine stippling or bronzing on leaves, faint webbing on undersides, foliage drying out during hot, dry weather.

Treatment

Spray foliage with a strong jet of water to dislodge mites. Apply insecticidal soap or horticultural oil to leaf undersides; repeat every 5–7 days as needed.

Slug and Snail Damage

Deroceras reticulatum
Symptoms

Large irregular holes chewed in leaves, with slime trails on foliage and soil.

Treatment

Hand-pick at night, set beer traps, or apply iron phosphate bait. Remove debris and mulch where they hide.