Rusty foxglove
Digitalis ferruginea · Scrophulariaceae
Needle-thin spires, as tall as a person, crowded with small honey-brown flowers netted in rust. They stand as dark seed heads all winter.
- Size
- 5 ft tall, 18 in wide
- Zones
- 4 to 8
- Light
- Full sun to part sun
- Flowers
- Late June to early August
- Pets
- Toxic (severe)
- Job in a bed
- Accent
A bed built around rusty foxglove
The planner designed this bed around rusty foxglove when this page was made: a 12 × 6 ft (3.7 × 1.8 m) cottage garden in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why rusty foxglove stands where it does.
The plants
- 1 Rusty foxglove × 3, orange
- 2 Winter heath × 3, pink
- 3 Carpathian bellflower 'Blue Clips' × 8, blue
- 4 Little bluestem 'The Blues' × 8, tan
- 5 Silver sage × 1, silver leaves
- 6 Brown-eyed Susan × 5, yellow
- 7 Ornamental onion 'Purple Sensation' × 5, purple
- 8 Spring starflower × 12, blue
Why this plant
- The only orange.
Why here
- Anchors a back corner. At 5 ft it is the tallest plant here, and the tallest close the ends of the bed, where they stand in front of nothing.
- A step in the back row. Next to little bluestem 'The Blues' (3 ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one clump. A single spire is too slight to hold a place alone, so here the accent is a clump.
Why now
- In flower for 7 weeks. From late June to early August.
- Part of the bed's peak. With Carpathian bellflower 'Blue Clips', little bluestem 'The Blues' and brown-eyed Susan in early August: 4 kinds at once. No week has more.
Planned as a cottage garden: 28 of the 28 plants (100%), bulbs aside, stand alone or in groups of no more than five, small enough for the kinds to mingle. The flowering is at its height in early August, with 4 kinds out together. Cool colours (pink, blue and purple) with orange and yellow as the warm notes, and tan to calm things between them.
The planner's own design check: 12 Excellent, 4 Good, 1 Satisfactory.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where rusty foxglove goes in a border
At 5 ft it belongs at the back of a bed. In the planner's ten height classes it is tall (4 to 5 ft). It is airy enough to see through, so it can also come forward and veil what is behind it.
Its job: accent. An upright plant used singly, like a punctuation mark, and repeated at intervals to give the bed rhythm.
The best vertical line in the naturalistic garden: a pencil stroke that lasts from June to February. A biennial or short-lived perennial, so let it seed.
- Slim vertical accents
- Winter seed heads
- Naturalistic planting with grasses
What to plant with rusty foxglove
Plants recorded as good partners for it, and what each pairing does:
- Mexican feather grass: in flower together for five weeks, from late June; low enough (20 in) to stand in front of it.
- Purple coneflower: purple against orange, opposite each other on the colour wheel, if you choose those colours, in flower together for seven weeks; low enough (3 ft) to stand in front of it.
- Sea holly: blue against orange, opposite each other on the colour wheel, in flower together for six weeks; low enough (3 ft) to stand in front of it.
Questions about rusty foxglove
Does rusty foxglove need sun or shade?
Rusty foxglove grows in full sun (6 or more hours of direct sun a day) and part sun (4 to 6 hours of sun, including some afternoon sun).
It wants ordinary well-drained soil, of average fertility, and little watering once settled.
What zones does rusty foxglove grow in?
USDA zones 4 to 8. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Above zone 8 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does rusty foxglove flower in my zone?
In zone 5 it flowers late June to early August. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 4 | Early July to mid August |
|---|---|
| Zone 5 | Late June to early August |
| Zone 6 | Late June to early August |
| Zone 7 | Late June to early August |
| Zone 8 | Late June to early August |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should rusty foxglove be planted?
16 in (40 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 18 in (45 cm), so a group knits into one patch.
It grows 5 ft (150 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many rusty foxglove plants do I need?
At 16 in apart, set out in staggered rows:
- 7 to fill 10 square feet (about 1 m²)
- 8 for a single row 10 ft (3 m) long
- 21 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as one at a time, repeated along the bed at intervals; a slender one reads better as a clump of three.
In the bed above, the planner used three in one group.
Is rusty foxglove poisonous to dogs and cats?
Yes: severe toxicity to people, dogs, cats and horses. All parts are highly poisonous if eaten and affect the heart; even small amounts can be life-threatening. Avoid it where children or pets may chew plants.
Rated from the ASPCA. Where references disagree, the more cautious rating is used.
Is there a pet-safe plant like rusty foxglove?
These come closest to doing what rusty foxglove does, and no toxicity is recorded for them:
- Hollyhock: the same job in a bed and the same flowering time; 12 in taller, pink, red or white, not orange.
- Blue vervain: the same job in a bed; 12 in shorter, flowers mid July to early September.
- Rattlesnake master: the same job in a bed and the same flowering time; 12 in shorter, white, not orange.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
Will rusty foxglove spread?
It seeds itself about; the risk of it taking over is moderate. Short-lived, and self-seeds freely in open ground. Thin the seedlings in spring.
What flowers after rusty foxglove?
Rusty foxglove is over by early August. These start as it finishes and carry the same spot on, so it never goes flat:
- Japanese anemone: from mid August to early October, 3 ft tall, to stand in front of it and cover its fading stems.
- Little bluestem 'Standing Ovation': from early August to mid September, 3½ ft tall, to stand in front of it and cover its fading stems.
- Lilyturf: from early August to mid September, 16 in tall, to stand in front of it and cover its fading stems.
What does rusty foxglove look like in winter?
Rusty foxglove holds some of its leaves into winter, more in a mild year or a sheltered spot, and they look tired by March. Cut the old ones off as new growth starts.
More Digitalis
- Foxglove Digitalis purpurea
- Foxglove 'Dalmatian Purple' Digitalis purpurea 'Dalmatian Purple'
- Straw foxglove Digitalis lutea
- Strawberry foxglove Digitalis x mertonensis
- Yellow foxglove Digitalis grandiflora
In these guides
- Garden plants toxic to cats
- Garden plants toxic to dogs
- Tall perennials and grasses for the back of a border
- Plants with spires: vertical accents
Every fact on record
- Type
- Perennial
- Size
- 5 ft (150 cm) tall, 18 in (45 cm) wide
- Plant
- 16 in (40 cm) apart
- Height class
- Tall (4 to 5 ft)
- Place in the bed
- Back, or further forward: it is airy enough to see through
- Flowers
- Late June to early August; upright spires; orange, tan
- Leaves
- Medium texture, semi-evergreen; dark green
- Shape
- Upright, self-seeding
- Hardy in
- USDA zones 4 to 8
- Light
- Full sun, part sun
- Soil
- Average, well-drained
- Water
- Low
- Feeding
- None needed
- Family
- Scrophulariaceae
Checked against ASPCA poison lists. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.