Northern mountain ash

Photo: Hedwig Storch — CC BY-SA 3.0 · source

Survives zone 2 through 6

Harvest calendar

Best planted in early spring after your last frost, or in fall before the ground freezes, depending on your climate.

Also called showy mountain ash — one of the hardiest rowans here, native well into Labrador. Shiny red fruit clusters persist after leaf drop, an important winter and early-spring food source for birds. ⚠ Not just astringent: raw fruit in this group contains parasorbic acid, which causes vomiting, stomach cramps and diarrhoea if you eat any quantity of it. Cooking, freezing, drying or a hard frost converts it to harmless sorbic acid — which is exactly why every traditional recipe cooks it and why the fruit is picked after the first frosts.

Hardiness

Zone 2–6

Habit

Tree

Edible part

Fruit

Ripens

Late summer, persisting after leaf drop

Mature size

6–9 m (20–30 ft) tall, 4.5–6 m (15–20 ft) spread

Light

Full sun

Soil pH

5.0–6.5 (acid) — humusy, well-drained loam

Environment

Boreal to temperate

Native range

Labrador and Newfoundland to Quebec, south to Iowa, New York and Maine, with scattered populations in the Appalachians to North Carolina.

Status

Wild

Years to fruit

4–6 yrs

Growth speed

Moderate

Spacing

500 cm (197 in) apart — about 25 m² (269 sq ft) per plant

Leaf shape

Pinnate with 11–17 leaflets, broader and bluer-green than the common rowan's and blunter at the tip — the quickest way to separate showy mountain-ash from S. americana.

Root system

Fibrous and moderately deep, spreading wider than the crown, with a tendency to sucker in some species. Tolerant of poor and thin soils but not of compaction or drought once established.

Fruit description

Shiny red pomes, about 1 cm across, in clusters

Propagation

Seed after cold stratification. Worth knowing which kind you have: the apomictic whitebeams and their relatives set seed asexually and come true, while the sexual rowans do not and their seedlings vary. Named clones are grafted, usually onto S. aucuparia.

Pollination

Hermaphrodite and insect-pollinated, and self-fertile like the other true rowans; a second tree still improves set.

The edible parts listed above are a starting point, not a field guide. Identify a plant with certainty — ideally against a local authority — before eating any part of it, and read the full disclaimer. Spotted something wrong? Report it.