Sunset hyssop
Agastache rupestris · Lamiaceae
Wiry stems of sunset-orange and lavender flowers above thread-fine, grey-green leaves that smell of root beer. A hummingbird magnet.
- Size
- 24 in tall, 18 in wide
- Zones
- 5 to 9
- Light
- Full sun
- Flowers
- Mid July to mid September
- Pets
- No toxicity recorded
- Job in a bed
- Drift
A bed built around sunset hyssop
The planner designed this bed around sunset hyssop 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 715 that suit those conditions and its dry soil, and says below why sunset hyssop stands where it does.
The plants
- 1 Sunset hyssop × 3, orange
- 2 Cheddar pinks 'Firewitch' × 13, pink
- 3 Sea thrift × 8, white
- 4 Little bluestem 'Standing Ovation' × 3, tan
- 5 Brown-eyed Susan × 5, yellow
- 6 Silver sage × 1, silver leaves
- 7 Ornamental onion 'Purple Sensation' × 5, purple
- 8 Lady tulip × 12, red
Why this plant
- The only spires. The others are globes, plumes, daisies and others. Shape reads at a distance, where colours blur.
- The only orange.
Why here
- At the back. At 24 in it is seen over Cheddar pinks 'Firewitch' (8 in) in front of it, and has nothing behind it to hide.
- A step in the back row. Next to brown-eyed Susan (4 ft) and little bluestem 'Standing Ovation' (3½ ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one group. Massed, one kind reads as a single shape. Scattered, it would look spotty.
Why now
- In flower for 11 weeks. From mid July to mid September.
- Fills a gap. For two of those weeks nothing else on the plan is in flower.
Planned as a cottage garden: 33 of the 33 plants (100%), bulbs aside, stand alone or in groups of no more than five, small enough for the kinds to mingle. Hot colours (orange, yellow and red) with pink and purple as the cool notes, and white and tan to calm things between them. The flowering is at its height from late May, with 3 kinds out together.
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.
Where sunset hyssop goes in a border
At 24 in it belongs in the middle of a bed. In the planner's ten height classes it is medium short (18 to 24 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
A plant of the American Southwest that needs sharp drainage and lean soil; winter wet kills it. Its smoky orange is easy to place and is at its best with silver foliage and blue flowers.
- Hot, dry, gravelly beds
- Hummingbird gardens
- Soft orange to blend with blues and silvers
What to plant with sunset hyssop
Plants recorded as good partners for it, and what each pairing does:
- Russian sage: in flower together for 10 weeks, from mid July; tall enough (4 ft) to stand behind it; happy in the same dry soil.
- English lavender 'Hidcote': purple against orange, opposite each other on the colour wheel, in flower together for three weeks; a low mound at the foot of its spires; happy in the same dry soil.
- Blue fescue: its blue-green leaves are a setting for the flowers, before and after; a low mound at the foot of its spires; low enough (10 in) to stand in front of it.
Questions about sunset hyssop
Does sunset hyssop need sun or shade?
Sunset hyssop 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. Once settled in, it stands drought.
What zones does sunset hyssop grow in?
USDA zones 5 to 9. It is hardy to zone 5, which means it survives winter nights down to about −10 °F (−23 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does sunset hyssop flower in my zone?
In zone 5 it flowers mid July to mid September. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 5 | Mid July to mid September |
|---|---|
| Zone 6 | Mid July to mid September |
| Zone 7 | Early July to mid September |
| Zone 8 | Early July to mid September |
| Zone 9 | Late June to mid September |
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 sunset hyssop be planted?
18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is about its full width, so each plant keeps its own outline.
It grows 24 in (60 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many sunset hyssop plants do I need?
At 18 in apart, set out in staggered rows:
- 5 to fill 10 square feet (about 1 m²)
- 7 for a single row 10 ft (3 m) long
- 17 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as a group of three or five, with a second group further along in the other number.
In the bed above, the planner used three in one group.
Is sunset hyssop poisonous to dogs and cats?
No toxicity is recorded for dogs, cats, horses or people, according to NC State Extension.
"Not toxic" is not "edible": a pet that eats a lot of any plant can be sick.
Do deer eat sunset hyssop?
Mostly not. NC State lists it as resistant to deer. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.
What flowers after sunset hyssop?
Sunset hyssop is over by mid September. 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.
- October daphne: from mid September to late October, 8 in tall, to stand in front of it and cover its fading stems.
- Meadow saffron: from mid September to mid October, 6 in tall, to stand in front of it and cover its fading stems.
What does sunset hyssop look like in winter?
Sunset hyssop 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.
Is sunset hyssop good for bees and butterflies?
Sunset hyssop is visited by bees, butterflies and hummingbirds.
It is native to the United States.
More Agastache
- Anise hyssop Agastache foeniculum
- Hyssop 'Black Adder' Agastache 'Black Adder'
- Hyssop 'Blue Boa' Agastache 'Blue Boa'
- Hyssop 'Blue Fortune' Agastache 'Blue Fortune'
- Texas hummingbird mint Agastache cana
In these guides
- Deer-resistant perennials for full sun
- Drought-tolerant perennials for full sun
- Pet-safe plants for a sunny border
- Native perennials for pollinators
- Plants for hummingbirds
- Plants for butterflies
- Plants for bees
- Plants with spires: vertical accents
- Silver and grey-leaved plants
Every fact on record
- Type
- Perennial
- Size
- 24 in (60 cm) tall, 18 in (45 cm) wide
- Plant
- 18 in (45 cm) apart
- Height class
- Medium short (18 to 24 in)
- Place in the bed
- Middle
- Flowers
- Mid July to mid September; upright spires; orange
- Leaves
- Fine texture, herbaceous; grey-green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 5 to 9
- Light
- Full sun
- Soil
- Lean, dry and sharply drained
- Water
- Low
- Feeding
- None needed
- Family
- Lamiaceae
- Comes from
- SW USA
- Attracts
- Bees, butterflies, hummingbirds
- Stands up to
- Deer, drought
Checked against NC State Extension. 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.