Perennials for zone 3

What grows in USDA zone 3, where winters reach −30 to −20 °F, and when it flowers there.

USDA zone 3 is where the coldest night of an average winter falls between −30 and −20 °F (−34 to −29 °C). Zones measure only that one night, so they say what will survive a winter, not how hot the summer is or how long the season runs.

496 of the planner's 1400 plants are hardy in zone 3. Below are the dozen to start with, when things flower in zone 3 month by month, the plants at the very edge of their range here, and a bed the planner designed for a zone-3 garden in full sun.

496 plants: 324 perennials, 23 ferns, 37 bulbs, 11 grasses and 101 shrubs.

The dozen to start with

Hens and chicks

4 in · grown for its leaves

Tight, fleshy rosettes, green or flushed with burgundy, surrounded by a crowd of smaller offsets.
Lady fern

2½ ft · grown for its leaves

The classic lacy fern: light green, finely cut, arching fronds that keep unfurling all summer.
Bleeding heart

2½ ft · mid May to mid June

An old-fashioned favourite with arching stems of heart-shaped flowers in late spring.
Little bluestem

3 ft · grown for its leaves · host plant

Blue-green summer blades turn copper and bronze in autumn and hold their colour through winter.
Bearded iris

2½ ft · early June to late June

Ruffled, often scented flowers in almost every colour stand above fans of grey, sword-shaped leaves in late spring.
Christmas fern

20 in · grown for its leaves

The most useful native fern: leathery, dark green fronds that stay green through winter, in a tidy clump that never spreads.
Delphinium

5 ft · late June to late July

The great blue spire of the English border: dense columns of flowers up to head height in early summer.
Snowdrop

6 in · late March to mid April

Nodding white bells that push up through the last of the snow, weeks before anything else.
Cinnamon fern

4 ft · grown for its leaves

A tall vase of green fronds surrounds stiff, upright, cinnamon-brown spore stalks in spring.
Ostrich fern

4 ft · grown for its leaves

Tall, feathery fronds form an elegant green vase that gives height at the back of a shady bed.
Common lilac

11½ ft · late May to mid June · host plant

The lilac of old farmyards: large, heavily scented flower trusses in lilac, purple, white or pink in mid-spring, on a tall, suckering shrub that can live for a century.
Winterberry

8 ft · grown for its leaves · host plant

A native holly that drops its leaves in autumn to show branches packed with bright red berries, which last into winter until the birds take them.

When things flower in zone 3

How many of these plants are in flower in each month in zone 3, and some of the familiar ones that open that month. Spring flowers here are about two weeks later than in zone 5.

Month	In flower	Opening this month
January	0
February	1
March	8	Snowdrop
April	32	Crocus, Daffodil and Daffodil 'Dutch Master'
May	115	Bleeding heart, Bugleweed and Bugleweed 'Burgundy Glow'
June	210	Asiatic lily, Bearded iris and Blanket flower 'Arizona Sun'
July	186	Black-eyed Susan, Butterfly weed and Coneflower 'Magnus'
August	178	Black-eyed Susan 'Goldsturm', Hosta 'Guacamole' and Little bluestem 'Standing Ovation'
September	108
October	34
November	3
December	0

A zone-3 bed

The planner designed this 16 × 8 ft (4.9 × 2.4 m) bed for zone 3 and full sun when this page was made.

A 16 × 8 ft (4.9 × 2.4 m) bed at eye level in early August: Bloody cranesbill 'Max Frei', Heath aster 'Snow Flurry', Fernleaf yarrow 'Cloth of Gold', New England aster 'Alma Pötschke', Mugo pine 'Mops', Little bluestem 'The Blues', Bergenia 'Bressingham White', Tulip, Crocus, Double snowdrop. — A 16 × 8 ft (4.9 × 2.4 m) English border in zone 3, full sun, seen from the path in early August.

From above, to scale. Each circle is one plant, as wide as the room it needs.

The plants

1 Bloody cranesbill 'Max Frei' × 8, pink
2 Heath aster 'Snow Flurry' × 13, white
3 Fernleaf yarrow 'Cloth of Gold' × 8, yellow
4 New England aster 'Alma Pötschke' × 4, pink
5 Mugo pine 'Mops' × 1, dark green leaves
6 Little bluestem 'The Blues' × 3, tan
7 Bergenia 'Bressingham White' × 3, white
8 Tulip × 12, red
9 Crocus × 12, purple
10 Double snowdrop × 12, white

Planned as an English border: 8 of the 8 groups (100%) are drifts, longer along the bed than they are deep. Fernleaf yarrow 'Cloth of Gold' and New England aster 'Alma Pötschke' anchor the back corners of the bed: the tallest plants on the plan stand there. White runs through the planting: 3 of the 9 kinds grown for their flowers have it.

The planner's own design check: 14 Excellent, 3 Good. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.

Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.

At the edge of their range in zone 3

Hardy to zone 3 and no colder (468). They survive a normal zone-3 winter but not a harder one: give them the warmest, best-drained spot you have, and a mulch in their first winter.

And 438 more.