PL. —Saxifraga oppositifoliaBotanical illustration — drop image
Saxifraga oppositifolia

Purple Mountain Saxifrage

Spring
1a6bHardiness zone
Peak bloom windowZone 6b · frost-offset weeks
Winter
In bloom
Spring
Peak bloom
Summer
Not in bloom
Fall
Not in bloom
Peak bloom
In bloom
Background

Saxifraga oppositifolia is a tight cushion-forming arctic-alpine perennial and one of the northernmost flowering plants on Earth, native to the high Arctic, Alps, Rocky Mountains, and northern Britain. Purple to rose-pink flowers open in earliest spring, often before surrounding snow has fully melted. It brings vivid early color to rock gardens, crevice gardens, and alpine troughs.

Excellent drainage is the overriding requirement. Plant in a vertical rock crevice or a sharply gritted mix at a near-neutral to slightly alkaline pH. Cool root temperatures are essential; prolonged summer heat causes rapid decline, which is why it rarely succeeds south of zone 6. A layer of fine grit around the crown sheds standing water and discourages crown rot. Cold hardiness is exceptional — winter temperatures are not a concern provided the crown stays dry.

Some indigenous Arctic peoples, including Inuit groups, have traditionally eaten the young leaves and stems raw or with animal fat, making this one of the few vascular plant foods available at extreme northern latitudes.

Care guide
SunFull sun
WaterLow; sharp drainage essential
SoilLean, gritty, well-drained, neutral to alkaline
Spacing6–8 inches
Height1–3 inches
Zone1a – 6b
Native RegionAK, CO, ID, MT, NH, NY, OR, UT, VT, WA, WY
Direct sowFrost hardy
Seasonal tasks
spring
watchCheck that the crown is not sitting in standing water after rain or snowmelt; regrade or add grit immediately if drainage is poor.
watchMonitor for slugs, which graze cushion shoots; apply iron phosphate bait or set copper barrier tape around troughs.
cutRemove spent flower stems and trim any browned cushion sections after peak flowering to keep the mat tidy and reduce rot risk.
sowPlant divisions or rooted cuttings into a gritty alpine mix in a rock crevice or trough as soon as soil is workable in early spring.
summer
watchMonitor for wilting or browning caused by summer heat; ensure grit mulch is in place around the crown and withhold supplemental water.
sowTake 2–3 cm stem cuttings in mid-to-late summer; root in a gritty propagation mix and overwinter young plants in a cold frame.
fall
watchBefore wet fall weather arrives, confirm drainage is optimal — winter wet, not cold, is the primary cause of plant loss.
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.

Root rot

Symptoms

Plants wilt, yellow, and stunt even in moist soil; lower stems and roots turn brown, soft, and mushy and the plant may collapse. Most common in heavy, wet, or poorly drained ground.

Treatment

Improve drainage and stop overwatering, and never plant too deep. Lift and destroy badly affected plants along with the soil around the roots. Grow in raised or free-draining beds to prevent it returning.

Botrytis (grey mould)

Symptoms

Grey fuzzy mould on petals and stems, worst in cool wet conditions.

Treatment

Remove affected parts immediately. Improve air circulation. Avoid overhead watering. Apply copper fungicide if severe.

From the field journal