Good to Grow: Cultivating Southern Blue Vervain
Blue vervain (Verbena hastata) likes full sun and wet (sometimes boggy) soils․ The plant produces candelabras of violet blue flowers from July to September․ It grows 4 to 6 feet (1․2 to 1․8 m) tall․ It is native to Tennessee and adjacent states‚ hardy in USDA plant hardiness zones 3 through 8 and as a perennial is suitable for growing in almost any garden in the southeastern United States from the Cumberland Plateau to the Mississippi River bottomlands․
The easy answer to that is yes‚ but only if you want to make a rain garden or pollinator patch․ It's a bit easier to grow than most wildflowers‚ provided you get the moisture in the right ballpark to start with․
What Is Blue Vervain Good For?
The plant makes its living in two very different ways․ Herbalists have used blue vervain for generations as a nervine‚ or plant that soothes an overactive nervous system․ The dried leaves and flowering tops are made into tea and tinctures for calming‚ sleep‚ and alleviating upset stomachs․ However‚ because it is very bitter‚ most people take it with a sweetener (usually honey) or mint․ We're not going to tell you it cures anything‚ but this stuff has been used for so long that contemporary herbalists still swear by it․
Second‚ and just as important for the Tennessee gardener‚ blue vervain is extremely attractive to wildlife‚ especially native bumblebees and long-tongued bees that visit the flower spikes from top to bottom for several weeks‚ and butterflies such as monarchs‚ swallowtails‚ and skippers that stop by for nectar․ By fall‚ goldfinches and sparrows come to pick at the seed heads․ Whether you're trying to create a pollinator corridor or get more birds to hang out in your yard come October‚ this plant means business․
Blue vervain's natural habitat and its ecological implications․
Blue vervain is a native wildflower found in wet meadows‚ the edges of ditches‚ ponds‚ swamps‚ and floodplain forests across most of North America‚ including the river bottoms of Tennessee․ Wetland habitat is the ideal clue to how to grow this species as a cultivated plant‚ as it cannot tolerate drought․ It wants soil which stays moist‚ and it genuinely doesn't mind standing water for short periods after a heavy rain․
Bluestem vervain is more ubiquitous than some realize․ Gardeners in Middle Tennessee with heavy clay soil have noted that it grows much better in clay than other easy plants do‚ as clay prevents moisture in the soil from draining as quickly as sandy loams do․ When you find a low area in your yard that nothing else seems to like‚ blue vervain will grow․
Blue vervain plants or seeds can generally be found at nurseries featuring native or pollinator plants․ TN Nursery offers the blue vervain‚ along with companion plants such as swamp milkweed and cardinal flower to suit similar conditions‚ in our native wildflower collection․ This benefit of having similar plants available in close range makes designing a rain garden easier․
Is Blue Vervain Easy to Grow? Here's the Real Timeline
Yes․ But that partly depends on your definition of easy․ It takes some time to establish the first year; seeds require cold‚ moisture stratification․ Outdoors this occurs naturally during winter․ If the seeds are sown indoors‚ this can be accomplished by storing for 60 days in a bag in a refrigerator․ Because germination can also be slow and erratic (generally three to four weeks as well)‚ most home gardeners prefer to use nursery-grown transplants if they want flowers the same year․
After the transplants are set out‚ preferably in spring after the last chance of frost (early to mid-April for most of Tennessee)‚ expect a modest gain in the first year as the plant spends most of its energy putting roots down․ Achieving a growth of two feet with a few flower spikes is typical․ By the second year‚ roots will be well rooted‚ plants will have reached their full height of four to six feet and flower profusely․ However‚ this two-year establishment period is true for most native perennials and may catch those hoping for drama in the first year severely off-guard․
For care‚ here's what really matters:
Soil and water: Keep the soil consistently moist‚ especially the first year․ Established plants tolerate short dry periods but sulk if drought lasts a week or two‚ resulting in lower leaves dropping․ If there is no natural wet spot nearby‚ a soaker hose on a timer can be used․
Sun: Full sun gives the strongest ‚ erect plants and fuller flower spikes‚ although partial shade will work․ Tall varieties that grow spindly in partial shade are the ones that need staking to stand tall․
Plant 18-24 inches (46-61 cm) apart․ While not particularly bushy‚ good air circulation will help reduce powdery mildew in Tennessee's humid summers‚ especially on those plants growing directly next to a fence or wall․
Deadheading and seeding: Blue vervain readily self-seeds when well established․ Remove the flower spikes before the seeds scatter if you would like a tidy flower bed․ If you prefer it more naturalized (and it is indeed best that way)‚ leave the seed heads for the birds‚ and let a few seedlings fill in the gaps next spring․
Winter care: The plants can also be cut back to a few inches after the first hard frost‚ or the stems can be left standing as insect habitat and bird food (either option works in Tennessee‚ as the cold causes no dieback‚ because it is the roots that survive through the winter)․
Where It Fits into the Garden
Because of the tall stature of blue vervain‚ it is best grown at the back of a mixed border‚ or interplanted with other tall plants in a meadow garden situation where the flower spikes are less likely to shade other garden plants․ It will grow in the company of Joe Pye weed‚ ironweed‚ and swamp milkweed‚ all three of which are Tennessee natives that prefer moist conditions and flower July to September․ When planted together‚ they form a tall wall of flowers that is buzzing with pollinators for most of the summer․
If you have a corner of your yard that is always wet and just doesn't seem to be anything but a nuisance‚ blue vervain may be the plant to make it the most interesting bed in your garden․
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