Globe thistle 'Blue Glow'
Echinops bannaticus 'Blue Glow' · Asteraceae
Perfect spheres of intense steel blue, larger and darker than those of the common globe thistle, on white-felted stems.
- Size
- 4 ft tall, 24 in wide
- Zones
- 3 to 8
- Light
- Full sun
- Flowers
- Mid July to late August
- Pets
- No toxicity recorded
- Job in a bed
- Accent
A bed built around globe thistle 'Blue Glow'
The planner designed this bed around globe thistle 'Blue Glow' when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, full sun. It chose the other plants from the 715 that suit those conditions and its dry soil, and says below why globe thistle 'Blue Glow' stands where it does.
The plants
- 1 Globe thistle 'Blue Glow' × 3, blue
- 2 Cheddar pinks 'Firewitch' × 16, pink
- 3 Heath aster 'Snow Flurry' × 4, white
- 4 Little bluestem 'The Blues' × 3, tan
- 5 Silver sage × 1, silver leaves
- 6 Oriental poppy 'Patty's Plum' × 3, purple
- 7 Tulip 'Lilac Wonder' × 8, pink
- 8 Schubert's allium × 2, pink
Why this plant
- The only blue.
Why here
- Anchors a back corner. At 4 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 oriental poppy 'Patty's Plum' (2½ 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 mid July to late August.
- Fills a gap. For four of those weeks nothing else on the plan is in flower.
Planned as an English border: 4 of the 5 groups (80%) are drifts, longer along the bed than they are deep. Little bluestem 'The Blues' and globe thistle 'Blue Glow' anchor the back corners of the bed: the tallest plants on the plan stand there. Cheddar pinks 'Firewitch' is the plant there is most of: 16 of the 40.
The planner's own design check: 13 Excellent, 3 Good, 1 Satisfactory. 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.
Where globe thistle 'Blue Glow' goes in a border
At 4 ft it belongs at the back of a bed. In the planner's ten height classes it is moderately tall (3 to 4 ft).
Its job: accent. An upright plant used singly, like a punctuation mark, and repeated at intervals to give the bed rhythm.
The globe is one of the essential shapes of the summer border, and this is the best blue. Plant it behind something that hides its coarse lower leaves, and leave the heads for the finches.
- Blue globes at the back of a dry border
- Bees and butterflies
- Cutting and drying
What to plant with globe thistle 'Blue Glow'
Plants recorded as good partners for it, and what each pairing does:
- Fernleaf yarrow 'Coronation Gold': blue against yellow, opposite each other on the colour wheel, in flower together for seven weeks; fine leaves against its bold ones; happy in the same dry soil.
- Russian sage: in flower together for seven weeks, from mid July; fine leaves against its bold ones; happy in the same dry soil.
- Switchgrass 'Northwind': in flower together for three weeks, from early August; fine leaves against its bold ones.
Questions about globe thistle 'Blue Glow'
Does globe thistle 'Blue Glow' need sun or shade?
Globe thistle 'Blue Glow' grows in full sun (6 or more hours of direct sun a day).
It wants dry, sharply drained soil, on the lean side, with no feeding, and little watering once settled.
What zones does globe thistle 'Blue Glow' grow in?
USDA zones 3 to 8. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °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 globe thistle 'Blue Glow' flower in my zone?
In zone 5 it flowers mid July to late August. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 3 | Mid July to late August |
|---|---|
| Zone 4 | Mid July to late August |
| Zone 5 | Mid July to late August |
| Zone 6 | Mid July to late August |
| Zone 7 | Early July to mid August |
| Zone 8 | Early July to mid 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 globe thistle 'Blue Glow' be planted?
20 in (50 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 24 in (60 cm), so a group knits into one patch.
It grows 4 ft (120 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many globe thistle 'Blue Glow' plants do I need?
At 20 in apart, set out in staggered rows:
- 4 to fill 10 square feet (about 1 m²)
- 7 for a single row 10 ft (3 m) long
- 14 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 globe thistle 'Blue Glow' poisonous to dogs and cats?
No toxicity is recorded for dogs, cats, horses or people, according to the ASPCA.
"Not toxic" is not "edible": a pet that eats a lot of any plant can be sick.
Is there a native plant like globe thistle 'Blue Glow'?
Globe thistle 'Blue Glow' is not native to North America. These North American natives come closest to doing its job:
- Rattlesnake master: the same job in a bed, the same size and the same flowering time; white, not blue, wants average soil.
- Prairie blazing star: the same job in a bed and the same flowering time; 4 in narrower, purple, not blue.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What flowers after globe thistle 'Blue Glow'?
Globe thistle 'Blue Glow' is over by late August. These start as it finishes and carry the same spot on, so it never goes flat:
- Garden chrysanthemum: from mid September to late October, 24 in tall, to stand in front of it and cover its fading stems.
- Sedum 'Autumn Joy': from mid August to mid October, 24 in tall, to stand in front of it and cover its fading stems.
- Montauk daisy: from mid September to late October, 3 ft tall, to stand in front of it and cover its fading stems.
What does globe thistle 'Blue Glow' look like in winter?
Globe thistle 'Blue Glow' dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
More Echinops
- Globe thistle Echinops ritro
- Globe thistle 'Arctic Glow' Echinops sphaerocephalus 'Arctic Glow'
- Globe thistle 'Veitch's Blue' Echinops ritro 'Veitch's Blue'
In these guides
- Pet-safe plants for a sunny border
- Tall perennials and grasses for the back of a border
- Plants with blue flowers
- Silver and grey-leaved plants
Zone guides: Zone 3 · Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8
Every fact on record
- Type
- Perennial
- Size
- 4 ft (120 cm) tall, 24 in (60 cm) wide
- Plant
- 20 in (50 cm) apart
- Height class
- Moderately tall (3 to 4 ft)
- Place in the bed
- Back
- Flowers
- Mid July to late August; globes; blue
- Leaves
- Bold texture, herbaceous; grey-green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 3 to 8
- Light
- Full sun
- Soil
- Lean, dry and sharply drained
- Water
- Low
- Feeding
- None needed
- Family
- Asteraceae
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.