Crested gentian
Gentiana septemfida · Gentianaceae
Clusters of deep blue bells, pale and spotted inside, at the tips of leafy, sprawling stems in late summer.
- Size
- 8 in tall, 14 in wide
- Zones
- 3 to 7
- Light
- Full sun to part sun
- Flowers
- Late July to early September
- Pets
- Not checked
- Job in a bed
- Drift
A bed built around crested gentian
The planner designed this bed around crested gentian 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 966 that suit those conditions, and says below why crested gentian stands where it does.
The plants
- 1 Crested gentian × 3, blue
- 2 Creeping phlox 'Candy Stripe' × 8, pink
- 3 False sunflower 'Summer Nights' × 3, yellow
- 4 Hyssop 'Blue Fortune' × 5, lavender
- 5 Globe arborvitae 'Danica' × 1, green leaves
- 6 Pincushion flower 'Butterfly Blue' × 5, lavender
- 7 Ornamental onion 'Purple Sensation' × 4, purple
- 8 Spring starflower × 7, white
Why this plant
- The only bells. The others are open bowls, daisies, spires and others. Shape reads at a distance, where colours blur.
- The only blue.
Why here
- On the front edge. At 8 in it frames the bed without hiding it, and it is in leaf all season. It finishes 26% of the edge.
- 3 plants in one run. An unbroken run of one kind gives the edge a clean line.
Why now
- In flower for 7 weeks. From late July to early September.
- Fills no gap. Every week it is in flower, at least three other kinds are too. It thickens a season that is already full.
Planned as an English border: 6 of the 6 groups (100%) are drifts, longer along the bed than they are deep. The most in flower at one time is 4 kinds, from late July. Pincushion flower 'Butterfly Blue' flowers longest, for 21 weeks.
The planner's own design check: 8 Excellent, 9 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 crested gentian goes in a border
At 8 in it belongs at the front of a bed. In the planner's ten height classes it is low (6 to 12 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
The easiest gentian, and the one to start with: it takes ordinary soil that does not dry out and tolerates lime. True blue in August is a rare thing at the front of a border.
- Late-summer blue at the front
- Rock gardens
- An easy first gentian
What to plant with crested gentian
Plants recorded as good partners for it, and what each pairing does:
- Coral bells: its burgundy leaves are a setting for the flowers, before and after.
- Carpathian bellflower: in flower together for five weeks, from late July.
- Lady's mantle: flowers first, late May to early July, so the spot is never empty; tall enough (18 in) to stand behind it; happy in the same moist soil.
Questions about crested gentian
Does crested gentian need sun or shade?
Crested gentian 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 soil that stays evenly moist, of average fertility, and a good soak in dry spells.
What zones does crested gentian grow in?
USDA zones 3 to 7. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °C).
Above zone 7 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 crested gentian flower in my zone?
In zone 5 it flowers late July to early September. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 3 | Early August to early September |
|---|---|
| Zone 4 | Early August to early September |
| Zone 5 | Late July to early September |
| Zone 6 | Late July to early September |
| Zone 7 | Mid July to early 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 crested gentian be planted?
12 in (30 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 14 in (35 cm), so a group knits into one patch.
It grows 8 in (20 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many crested gentian plants do I need?
At 12 in apart, set out in staggered rows:
- 12 to fill 10 square feet (about 1 m²)
- 11 for a single row 10 ft (3 m) long
- 38 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.
What flowers after crested gentian?
Crested gentian is over by early 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.
- Meadow saffron: from mid September to mid October, 6 in tall, to stand in front of it and cover its fading stems.
- Autumn crocus: from mid September to mid October, 5 in tall, to stand in front of it and cover its fading stems.
What does crested gentian look like in winter?
Crested gentian 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 Gentiana
- Bottle gentian Gentiana andrewsii
- Stemless gentian Gentiana acaulis
- Willow gentian Gentiana asclepiadea
In these guides
Every fact on record
- Type
- Perennial
- Size
- 8 in (20 cm) tall, 14 in (35 cm) wide
- Plant
- 12 in (30 cm) apart
- Height class
- Low (6 to 12 in)
- Place in the bed
- Front
- Flowers
- Late July to early September; hanging bells; blue
- Leaves
- Fine texture, herbaceous; dark green
- Shape
- Mounding, clumping
- Hardy in
- USDA zones 3 to 7
- Light
- Full sun, part sun
- Soil
- Average, evenly moist
- Water
- Moderate
- Feeding
- None needed
- Family
- Gentianaceae
Not yet checked against an outside reference: its figures rest on general horticultural knowledge. 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.