Shade Perennials by Zone
A decision table: how cold each shade perennial takes, and how dark a spot it will tolerate.
Shade perennials by zone come down to two questions: will it survive your winter, and will it flower or fill in with the light you have. The table below answers both from NC State’s Plant Toolbox, which lists a hardiness range and the light each plant tolerates.
NC State defines full sun as 6 or more hours of direct sun a day, partial shade as 2 to 6 hours, and deep shade as less than 2 hours.
Shade perennials at a glance: For the coldest gardens, hosta, astilbe, bleeding heart, foamflower, Solomon’s seal, brunnera, lungwort and maidenhair fern are rated to US Zone 3. Japanese forest grass and epimedium start at US Zone 5. For deep shade (under 2 hours of sun), choose hosta, bleeding heart, brunnera, foamflower, Solomon’s seal or maidenhair fern.
Want colour in a shady basket? See Growing Fuchsia in Canada for the classic shade basket plant.
The Decision Table
| Plant | US Hardiness (coldest) | Deep shade? | Notes |
|---|---|---|---|
| Hosta | Zone 3 | Yes | Foliage plant; see hostas |
| Astilbe | Zone 3 | No (dappled/partial) | Needs moisture; see astilbe |
| Bleeding heart | Zone 3 | Yes | Goes dormant in summer; see bleeding heart |
| Foamflower (Tiarella) | Zone 3 | Yes | |
| Brunnera | Zone 3 | Yes | |
| Solomon’s seal (Polygonatum biflorum) | Zone 3 | Yes | |
| Maidenhair fern (Adiantum pedatum) | Zone 3 | Yes | |
| Lungwort (Pulmonaria saccharata) | Zone 3 | No (partial) | |
| Coral bells (Heuchera) | Zone 3 | No (partial) | |
| Japanese forest grass (Hakonechloa) | Zone 5 | Yes | Milder gardens only |
| Epimedium | Zone 5 | Yes | Milder gardens only |
Zones in this table are US (USDA) hardiness zones from NC State’s Plant Toolbox, which are built differently from Canadian zones; use them to compare plants, and see USDA vs Canadian zones.
Reading It for Your Garden
Find your Canadian zone first with the zone finder. The US ratings are best used as a ranking: plants rated to US Zone 3 are the safe group for the Prairies and the North, and the US Zone 5 plants belong in the milder parts of southern Ontario, the Atlantic coast and BC.
Dry Shade Versus Moist Shade
Shade under trees is often dry as well as dark, because the roots take the water. NC State notes astilbe needs moisture and its foliage declines in drought. Bleeding heart, according to the same source, dislikes wet soil in winter and dry soil in summer. Group plants by water as well as light.
What Garden Trials Add
The Chicago Botanic Garden grows perennials side by side for four years or more with minimal care, letting them thrive or fail, in a US Zone 5b garden. Two of its shade trials are useful for choosing within a plant group.
Brunnera. Its trial found the silver-leaved types hold up best in heat and humidity, naming ‘Jack Frost’, ‘King’s Ransom’, ‘Langtrees’, ‘Looking Glass’, ‘Sea Heart’ and ‘Silver Heart’. White-edged ‘Dawson’s White’ burns easily in too much sun or heat and dislikes drought. It also advises removing spent flower heads to keep plants tidy and cut down on self-sown seedlings.
Ferns. Since 2002 the garden has trialled 26 painted ferns and lady ferns. It rates the genus (Athyrium) to US Zones 3–8 and calls lady ferns durable, hardy plants; ‘Encourage’ was among the best lady ferns in its trial. Japanese painted fern is rated to US Zone 5, so in colder Canadian gardens the lady ferns are the safer choice.
As in the table above, these are US zone ratings: use them to compare plants, not as a direct match to your Canadian zone.
Frequently Asked Questions
What perennials grow in deep shade in Canada?
From NC State's list: hosta, bleeding heart, brunnera, foamflower, Solomon's seal and maidenhair fern tolerate deep shade, meaning less than 2 hours of direct sun.
What shade perennials are hardiest?
Hosta, astilbe, bleeding heart, foamflower, brunnera, Solomon's seal, lungwort, coral bells and maidenhair fern are all rated to US Zone 3 by NC State.
Are US hardiness zones the same as Canadian zones?
No. US (USDA) zones are built differently, so use the US ratings to compare plants rather than as a direct match to your Canadian zone.
What counts as partial shade?
NC State defines partial shade as 2 to 6 hours of direct sun a day, and deep shade as less than 2 hours.
Does astilbe grow in full shade?
It does best in dappled or partial shade with consistent moisture, according to NC State.
What grows under trees?
Choose deep-shade plants and water them through dry spells, since tree roots take much of the moisture.
Sources
- North Carolina State University Extension Gardener Plant Toolbox — plant pages for hosta, heuchera, brunnera, pulmonaria, Solomon’s seal, foamflower, maidenhair fern, Japanese forest grass and epimedium
- North Carolina State University Extension Gardener Plant Toolbox — Astilbe x arendsii
- North Carolina State University Extension Gardener Plant Toolbox — Lamprocapnos spectabilis (bleeding heart)
- Chicago Botanic Garden, Hawke — Brunnera plant trial results (Fine Gardening, 2015)
- Chicago Botanic Garden — Painted and lady fern trial results