Blue vervain
Verbena hastata · Verbenaceae
Branched candelabras of pencil-thin, violet-blue spikes in summer, on tall, stiff stems. A native of wet meadows.
- Size
- 4 ft tall, 18 in wide
- Zones
- 3 to 8
- Light
- Full sun
- Flowers
- Mid July to early September
- Pets
- No toxicity recorded
- Job in a bed
- Accent
A bed built around blue vervain
The planner designed this bed around blue vervain 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 blue vervain stands where it does.
The plants
- 1 Blue vervain × 3, blue
- 2 Winter heath × 11, pink
- 3 Coral bells 'Firefly' × 8, red
- 4 Wild quinine × 3, white
- 5 Fernleaf peony × 1, red
- 6 Rose turtlehead × 5, pink
- 7 Hyacinth × 12, purple
- 8 Star of Persia × 5, purple
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 rose turtlehead (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 9 weeks. From mid July to early September.
- Part of the bed's peak. With coral bells 'Firefly' and wild quinine in mid July: 3 kinds at once. No week has more.
Planned as a cottage garden: 31 of the 31 plants (100%), bulbs aside, stand alone or in groups of no more than five, small enough for the kinds to mingle. Winter heath is the first into flower, in late January, and rose turtlehead the last to finish, in late September. Blue vervain and wild quinine anchor the back corners of the bed: the tallest plants on the plan stand there.
The planner's own design check: 12 Excellent, 5 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 blue vervain 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). 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 narrow spikes make a fine vertical texture among the broad heads of Joe Pye weed and milkweed. Each plant is short-lived, but it self-seeds in moist soil.
- Rain gardens and wet meadows
- Slim blue verticals
- Native pollinator planting
What to plant with blue vervain
Plants recorded as good partners for it, and what each pairing does:
- Swamp milkweed: in flower together for five weeks, from mid July; happy in the same moist soil.
- Joe Pye weed 'Gateway': in flower together for seven weeks, from late July; bold leaves against its medium ones; happy in the same moist soil.
- Boneset: in flower together for six weeks, from early August.
Questions about blue vervain
Does blue vervain need sun or shade?
Blue vervain grows in full sun (6 or more hours of direct sun a day).
It wants soil that stays evenly moist, of average fertility, and a good soak in dry spells. It copes with soil that stays wet.
What zones does blue vervain 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 blue vervain flower in my zone?
In zone 5 it flowers mid July to early September. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 3 | Mid July to early September |
|---|---|
| Zone 4 | Mid July to early September |
| Zone 5 | Mid July to early September |
| Zone 6 | Mid July to early September |
| Zone 7 | Early July to early September |
| Zone 8 | Early 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 blue vervain 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 4 ft (120 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many blue vervain 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 blue vervain 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 blue vervain?
They may. NC State does not list it as resistant to deer or rabbits. Where they visit, protect it, or plant it among ones they avoid.
Will blue vervain spread?
It seeds itself about; the risk of it taking over is moderate. Short-lived, but keeps going by self-seeding. Thin or move seedlings where they are not wanted.
What flowers after blue vervain?
Blue vervain 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, 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.
- New York aster: from late August to mid October, 3 ft tall, to stand in front of it and cover its fading stems.
What does blue vervain look like in winter?
Blue vervain dies down, but leave the stems standing: the seed heads stand through the winter, and songbirds eat the seed. Cut them down in early spring, before the new shoots come.
Is blue vervain good for bees and butterflies?
Blue vervain is visited by pollinators, specialist bees, butterflies and songbirds.
It is a host plant: the caterpillars of common buckeye feed on its leaves. A butterfly can only lay its eggs on its host plants, so these do more for it than any nectar flower.
It is native to the United States and Canada.
More Verbena
- Tall verbena Verbena bonariensis
In these guides
- Plants for wet soil and rain gardens
- Pet-safe plants for a sunny border
- Native perennials for pollinators
- Garden plants native to Canada
- Plants for butterflies
- Plants for bees
- Plants that feed garden birds
- Tall perennials and grasses for the back of a border
- Plants with spires: vertical accents
- Plants with blue flowers
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, 18 in (45 cm) wide
- Plant
- 16 in (40 cm) apart
- Height class
- Moderately tall (3 to 4 ft)
- Place in the bed
- Back, or further forward: it is airy enough to see through
- Flowers
- Mid July to early September; upright spires; blue
- Leaves
- Medium texture, herbaceous; green
- Shape
- Upright, self-seeding
- Hardy in
- USDA zones 3 to 8
- Light
- Full sun
- Soil
- Average, evenly moist
- Water
- Moderate
- Feeding
- None needed
- Family
- Verbenaceae
- Comes from
- North America
- Attracts
- Pollinators, specialist bees, butterflies, songbirds
- Host plant for
- Common buckeye
- Stands up to
- Wet soil
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.