Swamp verbena (Verbena hastata) is a herbaceous perennial flowering plant from the Verbenaceae family native to areas in the Great Lakes region of North America, including parts of Canada and various states in the US. It consists of around 150 species in the genus Verbena.
The plant is known by multiple names, including blue vervain, wild hyssop, swamp vervain, ironweed, and simpler’s joy.
This article will cover some of the health benefits, native habitats, wildlife, propagating, growing, and other useful tips about verbena hastata.
|Type of Plant:||Herbaceous perennial, Herb, Native Plant, Wildflower|
|Common Names:||Herb of Grace, ironweed, false vervain, Wild Vervain, blue verbena, Vervain, Herba Veneris, American vervain, Swamp Verbena, Simpler’s Joy, American blue vervain, Blue Vervain, Wild hyssop, swamp vervain|
|USDA Growing Zones:||3-9|
|Light:||Partial to Full Sun|
|Color of Blooms:||Purple, Blue|
|Length of Blooms:||Summer Into Fall, Blooms from bottom to top (couple at a time)|
|Water Quality:||pH of 5.6-7.5|
|Depth for Planting:||1/8″ Deep for Seeds|
|Soil:||Moist, Occasionally Wet|
Uses, Benefits & Facts
Many people with invasive species such as purple loosestrife, foxglove, or European wand loosestrife should choose blue verbena as a substitute.
Often doing very well in poorly maintained wetlands or marshy areas- and perfect for backyard ponds along pond edges.
Leaves have a “spear shape,” hinted at by the plant’s scientific epithet, hastata—featuring shoots that provide a spikey appearance in the summer into fall. Often grouped in clusters, the inflorescences look similar to a candelabra. They regularly reach a height of around 5 feet tall.
On the spikes are small blossoms with purple-blue hues, similar to lavender. The blooms slowly open from the bottom to top of each spike, or inflorescence. Leading to longer blooms.
Many birds enjoy the swamp verbena seeds, such as field sparrow, song sparrow, slate-colored junco, and cardinal.
The plant’s leaves have a bitter taste, so animals that graze often leave them alone. But, occasionally, rabbits (mainly cottontail ) may eat blue vervain.
However, the bitterness of the leaves does have benefits. It is associated with ethnobotanical use for specific disorders in humans (internally and externally). Including:
(Reference – PDF)
It also has qualities that suggest anticancer (Edewor & Usman, 2012) and has flavonoid that help prevent inflammation.
Although, you should use caution, as Blue vervain can alter the effects of some medications such as blood pressure and hormone therapy. Not to mention, taking large amounts could lead to diarrhea and vomiting.
Pollinators love swamp verbena, so it is great for ponds and gardens. Many types of bees (short and long-tongued) love their flowers and harvest their nectar and pollen. In addtion, other types of bees include:
- Eucerine miner
- Halictid bees
- Epoline cuckoo bees
- Verbena bee (a specialist to this plant)
Thick-headed flies, thick-waisted wasps, and solider beetles are also attracted to the summertime blooms.
Climate, Hardiness & Growth
You will often find swamp verbena in marshes, ponds, river-bottom prairies, disturbed sites, lakes, ditches, and the edges of creeks in moist soil. Although, it is possible to find in woodlands if there is a nearby water source. The roots are perfectly at home in a couple of inches of water, which is often common in its native habitats during brief floods.
These plants use rhizomatous growth to spread but may also self-seed if pollinators are abundant.
Swamp verbena has a moderate to fast growth rate and not known to be invasive.
Partial to full sun is best (although you will get fewer blooms and bushier plants in partial sun) and a slightly acidic soil pH.
Propagating & Planting Verneba Hastata
You can propagate these plants fairly quickly using stem cuttings or sowing seeds.
You can purchase seeds from a commercial supplier or collect them from plant nutlets. Which can be found in the fall (be sure to collect them before they naturally break open).
Put the nutlets in a dry location, and after a couple of days, you should be able to break them open to access the seeds.
The seeds will need to be cold-stratified (40F), which mimics going through winter before sowing. Otherwise, you may not be able to get them to germinate.
Once the seeds have been stratified, you can plant them in a pot 1/8″ deep in the soil and place them in a sunny area.
The best temperatures are around 60-70 F for successful growing.
Once seedlings are established, you can transplant them outdoors.
If you prefer to propagate using stem cuttings, you will want to complete this in the early spring. First, find healthy stems to obtain cuttings measuring about 3-4″.
After you have these, the next step is to remove the leaves around the base of the cutting. Next, expose the nodes and plant in a rooting soil (perlite seems to do well with swamp verbena).
You don’t want intense sun on cuttings- instead, select a partial sun location and keep the soil moist. The growth of new roots should begin in a couple of weeks. Then, just like the seed-grown plants, once they are adequately estabilshed, you can transplant them outdoors.
You can propagate blue vervain by division. Works best in the spring months.
Swamp verbena is low maintenance due to the plants’ ability to withstand droughts and tolerate excess nutrients, salt, and sand.
If you want to control swamp verbena’s spread or prefer bushier plants, you can deadhead (pinch the tops) of shoots. You are preventing the plant from self-seeding.
This plant does well against pests. Seldom needed any pest treatment. Although, if you do notice something is attacking it, it is best to take action sooner rather than later.
Since V.hastata natively grows in USDA zones 3-9, it naturally experiences winter. Therefore, the plant will naturally die back as the colder temperatures start—there is no need to bring the plants indoors during winter.
Although, protecting the root crown is a wise idea in case of severe temperature drops.
Swamp verbena enters a dormant state during winter and does not need a lot of water. In fact, too much moisture could lead to damaging the plant’s roots. Therefore, only resume watering if needed when the temperatures rise in the spring when new growth appears.
Toxic or Invasive?
Toxic or Beneficial?
As stated above, most avoid the plant due to the bitter-tasting leaves, but animals and humans usually tolerate small amounts (avoid large qualities) of swamp verbena.
If you want these benefits, one way to get around the bitter taste is to bitter-tasting leaves with other ingredients. Or, dry the seeds and consume roasted or ground up (the preferred method of consumption).
Generally this plant is no an aggressive spreader. You can control the spread via deadheading if needed, or grow in containers. Other competing plants will also help keep growth under control.
Where to Purchase Swamp Verbena Plants & Seeds
While you can sometimes find Verbena hastata plants in pots, it is not very common. Therefore, you will have difficulty finding them in North American garden centers unless you special order them.
It is usually much easier to purchase swamp verbena seed online through commercial vendors. Then, follow the steps for propagation outlined above for growing.
As always, check with your area’s regulations to ensure this plant is allowed. Although, most reputable sellers should have this information. Plus, Verbena hastata is not known to be highly invasive, so it should not have many restrictions.
The following video helps to identify blue vervain and talks about some of the health benefits:
Verbena hastata: A native plant ideal for prairie gardens and harsh landscapes : PDF
Edewor, T. I & Usman, L. A. 2012. Cytotoxicity and antibacterial activity of the leaf methanolic extract of Verbena hastata. Journal of Medicinal Plants Research Vol. 6(1), pp. 55- 58. DOI: 10.5897/JMPR11.823
Verbena hastata NC State – Link
Davin is a jack-of-all-trades but has professional training and experience in various home and garden subjects. He leans on other experts when needed and edits and fact-checks all articles.