If there has been one star plant of my garden this summer, it has been blue vervain (Verbena hastata). I didn’t see it coming, but I have fallen head over heals in love with this plant.
After about 15 years of growing all kinds of plants, I didn’t think it was possible for a new plant to completely charm me the way this one has. But blue vervain did.
I originally planted it for a very specific reason: I wanted another host plant for common buckeye butterflies. What I got was so much more.
All summer, its tall purple flower spikes have been busy with bees, wasps and butterflies. I’ve found groups of sleeping bees clinging to the flowers in the early morning. Green lynx spiders have taken up hunting positions among the leaves. I’ve found wavy-lined emerald moth caterpillars wearing pieces of flowers as camouflage.
And finally, a common buckeye butterfly found it too. All of that from a handful of seeds given to me by another gardener.
My Blue Vervain Started With Shared Seeds
The seeds came to me as a gift from a gardening student in the Online Gardening Academy™ community that I help facilitate for my job with joe gardener®.
That’s one of the things I love about gardening. A little envelope of seeds passes from one gardener to another, and months later you’re standing in the garden watching an entirely new community of life gather around the plants that grew from them.
Because blue vervain is a native perennial with some seed dormancy, the seeds benefit from a period of cold, moist stratification before spring sowing. This mimics the cold, damp conditions the seeds would experience naturally through winter.
For spring seed starting, give blue vervain seed at least 30 days of cold, moist stratification in the refrigerator. This was already done by the person who gifted me the seeds.
After stratification, surface sow the tiny seeds onto moist seed-starting mix and gently press them into contact with the surface. Don’t bury them. Blue vervain seeds need light for germination.
You can also let winter do the work for you by sowing the seeds outdoors in late fall or winter.
I started mine in a square tray filled with Pro-Mix seed-starting medium rather than planting them individually in cells. The seeds were so small so I just scattered them evenly across moist soil.
Once they germinated (which took about 10 days) and grew several sets of true leaves, I simply pulled apart the seedlings. I gently separated the roots and planted each seedling individually.
Their permanent home became a new raised bed we built specifically for native plants. They apparently approved of the arrangement.
It was a slow start with a cold and rainy spring but once the days got warmer, these plants took off.
What Is Blue Vervain?
Blue vervain, Verbena hastata, is a native North American perennial wildflower in the verbena family. It’s sometimes also called swamp vervain, swamp verbena, blue verbena or, rather wonderfully, “simpler’s joy.”
It naturally occurs in places that tend to hold some moisture: wet meadows, streambanks, marsh edges, ditches and other damp, sunny habitats.
Plants generally reach somewhere around 2 to 5 feet tall, although growing conditions can influence their eventual size. They prefer full to partial sun and moist soil.
But it’s the flowers that make blue vervain so distinctive.
Rather than producing one big showy bloom, the plant sends up slender, branching spikes covered in tiny violet-purple flowers. The flowers gradually open from the bottom of each spike upward.
The whole plant has this airy, almost candelabra-like appearance.
Up close, it gets even better.
A Plant That Collects Its Own Confetti
One of my favorite things about blue vervain is the petals. As the tiny purple flowers finish blooming, individual petals fall onto the long, lance-shaped leaves below. The slightly cupped leaves catch them.
Again and again this summer, I’ve found tiny purple petals resting there, as though the plant has been collecting its own confetti.
It’s one of those little details I probably wouldn’t have noticed if I weren’t constantly wandering around the garden with a macro lens.
And it’s also a good example of why I love growing plants that invite you to look closer.
Because once I started looking closely at this one, I discovered there was almost always something happening on it.
Blue Vervain Is a Pollinator Plant
The blue vervain flowers have been busy all summer.
Bees and wasps constantly work their way along the flower spikes, visiting one tiny bloom after another. Blue vervain is known to attract both long- and short-tongued bees as well as several other groups of pollinating insects.
There’s even a specialist bee associated with verbena.
But I’ve discovered that the relationship between bees and my blue vervain doesn’t necessarily end when the sun goes down.
Some of them sleep there. On several mornings I’ve gone outside early with my camera and found groups of long-horned bees still asleep, their little jaws or legs grasping the flower spikes while they wait for the day to warm up.
One morning I found a group of four together. There’s something ridiculously endearing about discovering that a plant you grew isn’t simply a place where an insect comes to eat but also where they spend the night.
And Where There Are Pollinators, There Are Predators
Of course, creating habitat doesn’t mean creating habitat only for the creatures we find cute.
Green lynx spiders discovered the blue vervain too. One day I found three of them hunting among the plants at the same time.
Green lynx spiders are active hunters often found on flowers and vegetation where pollinating insects gather. Rather than building a web to catch prey, they wait among the foliage and ambush insects that come within reach.
So while I may have planted blue vervain thinking about butterflies and caterpillars, the plant became part of a much more complicated little food web.
That’s what happens when we plant for biodiversity. We don’t really get to decide who moves in, and that includes spiders.
The Caterpillar Wearing Blue Vervain as Camouflage
Then there was one of my favorite discoveries of the summer: a tiny caterpillar covered in pieces of purple flower.
Wavy-lined emerald moth caterpillars (Synchlora aerata) are extraordinary little masters of disguise.
These caterpillars actually cut or collect tiny pieces of flowers, petals and other plant material and attach them to their bodies. Instead of merely being colored like their surroundings, they essentially dress themselves in their surroundings.
As the plant material wilts, they may replace it with fresher pieces.
Finding one wearing bits of flower from the garden is a reminders that camouflage in nature can be much stranger and more sophisticated than simply being green or brown.
And because blue vervain produces so many tiny flowers over such a long period, apparently it also makes a rather nice caterpillar wardrobe.
I Planted Blue Vervain for Common Buckeye Butterflies
As much as I’ve loved discovering all these unexpected visitors, there was one insect I was especially hoping to see.
The common buckeye (Junonia coenia).
Blue vervain is one of the larval host plants used by common buckeye caterpillars. That means a female buckeye can lay eggs on the plant and, after those eggs hatch, the caterpillars can feed on its foliage.
That’s an important distinction when we talk about gardening for butterflies.
A nectar plant feeds an adult butterfly, and a host plant helps make the next butterfly.
And ideally, I want my garden to provide both.
I’ve encountered buckeye caterpillars before. Several years ago, I photographed one feeding on snapdragon, another plant they can use as a host.
So when I started planning this new native bed, blue vervain was partly an invitation: Buckeyes welcome!
And Finally, a Buckeye Found It
Late this summer, it finally happened. A common buckeye appeared on the blue vervain.
Granted, it wasn’t doing exactly what I’d hoped. Instead of inspecting the leaves and laying eggs, the adult was drinking nectar from the flowers. I’ll take it!
The plant I grew from seed specifically because I wanted to support buckeyes had finally been found by a buckeye.
I haven’t discovered eggs or caterpillars on it yet. But now I know the butterflies are visiting the plant.
Maybe this year I’ll get lucky, or maybe it will happen next year. Gardening for wildlife involves a fair amount of patience.
You can plant the host plant and stop using pesticides. You can provide water, shelter and nectar and create all the conditions you can think of.
But you can’t order a butterfly to show up. You plant the invitation and wait.
Blue Vervain Supports More Than Butterflies
My own observations this summer have already convinced me of blue vervain’s wildlife value, but there’s much more going on with this plant than what I’ve managed to photograph.
Its visitors can include numerous native bees, wasps, flies and beetles. It’s also a host plant for verbena moth caterpillars in addition to common buckeyes.
After flowering, blue vervain produces small seeds that can become food for birds, including cardinals, song sparrows, field sparrows, swamp sparrows and juncos.
Even rabbits may occasionally browse the foliage, although the plant’s bitter taste makes it less appealing to many mammalian herbivores.
In other words, this isn’t just a butterfly plant. It’s a small piece of wildlife habitat.
How to Grow Blue Vervain From Seed
If you’d like to grow blue vervain yourself, starting it from seed is very doable, but the seed’s natural dormancy needs to be taken into account.
For spring sowing:
- Give the seeds at least 30 days of cold, moist stratification. I do this with a damp paper towel in a zip lock bag in the fridge.
- Fill a container or tray with a moist seed-starting medium.
- Scatter the seeds over the surface.
- Press them gently against the mix but don’t bury them. They need light to germinate.
- Keep the medium consistently moist while you wait for germination.
- Once seedlings are large enough to handle, separate or transplant them.
- Plant them into their permanent location after they’ve been hardened off and conditions are suitable.
If you’d rather skip refrigerator stratification, sowing outdoors in late fall or winter allows natural winter temperatures to provide the cold period.
Blue vervain prefers full sun to partial shade and generally does best in soils that stay moderately moist. In the wild, it’s associated with wet meadows, stream banks, marshes and other places where moisture is readily available.
Once established, it is a perennial and can also spread by rhizomes, so give it some room.
Would I Grow Blue Vervain Again?
Without hesitation. I started these plants because I wanted another host plant for common buckeye butterflies.
Instead, I got flowers that remind me of tiny purple candelabras. Leaves sprinkled with their own floral confetti. Bees coming for nectar. Bees sleeping in groups on the flowers. Hunting green lynx spiders. Butterflies. Wasps. A caterpillar that cuts up flowers and wears them as clothing.
And finally, the buckeye I had been waiting for. I still haven’t found a buckeye caterpillar on my blue vervain.
But the summer isn’t quite over. And the invitation is still open.
I shared more of what was happening in the garden around the blue vervain, along with a few other late-summer discoveries, in my recent Nearing Summer’s End newsletter on Substack.
You might also like this one: How to Start Passion Vine from Seed.
