discuss the proper care and maintenance of these brilliant blue-flowering plants.

Great blue lobelia (Lobelia siphilitica) gets less attention than it deserves. This plant is a member of the bellflower family (Campanulaceae). This family of flowering plants contains well over two thousand species, many of which are familiar garden plants.

This native species provides a dramatic splash of late-season color to your moisture-rich garden plot. While its natural habitat includes woodland stream-sides and wetland borders, you can enjoy a vibrant patch in your native plant garden, woodland garden, or naturalized rain garden.

You’ll definitely want this flower if you want to attract hummingbirds and pollinators to your garden. It will also help increase curb appeal, especially in late summer as your spring and summer-blooming plants are fading, helping extend the growing season or acting as a transition between your summer and fall-blooming blooms.

If you’ve got a bit of space and a moist garden plot, let’s dig right in and get to know the great blue lobelia and everything you need to successfully grow your own.
Plant Natural History
Great blue lobelia is a wildflower native to central and eastern North America, from Canada south to Texas and east to the Atlantic coast. It loves wet environments. You’ll find it growing along streams sides and around swampy edges. It grows near cool springs and in moist meadows. It isn’t too picky about sun or shade as long as it enjoys organically rich, consistently moist soil conditions.

This wildflower inhabits not only wetland borders but can also be found in both woodlands and grasslands. It’s widespread, although not particularly common within its range. This is a valuable wildlife plant, favored by a variety of insect pollinators and hummingbirds. All parts of this plant are mildly poisonous to humans, however, and should not be consumed in any way.

Characteristics
This native wildflower is an herbaceous perennial. It grows up to four feet tall and up to one-and-a-half feet wide. In ideal conditions, lobelia spreads by self-seeding and root rhizomes, creating attractive colonies without becoming aggressive.

These plants develop several sturdy, upright stems. Each stem is lined with alternate, finely-toothed, lance-shaped leaves of a uniformly green color. They grow vigorously during the growing season and the above-ground foliage dies back completely after the first frost.

Plants begin blooming in mid-to-late summer and continue into early fall, especially in cooler climates. The flower spikes are very showy and dramatic, typically reaching over six inches long. Numerous purplish-blue flowers line the flowering stems, opening from the bottom to the top. Each tubular flower has three prominent lower lobes and two upper lobes that are significantly less pronounced.

Propagation
Propagate by seed or division of mature clusters. If you’re just getting started, you might be able to find great blue lobelia at a nursery specializing in native plants. If you can’t find potted plants, starting from seed is a good way to introduce these plants to your landscape. If you already have lobelia growing in your yard, division is a great way to quickly start new patches of vegetation.

Seed
Direct sow seeds in the fall and allow them to overwinter on site. You won’t need to bury the seeds because they need light to germinate, but don’t expect to see any tiny seedlings until after your seeds have overwintered. It’s important to sow the seeds in a location where they will stay fairly moist, particularly in late winter and early spring. Not all the seeds you sow will germinate, but all you need are a few successful seedlings to start a beautiful colony of lobelia plants.

After your seeds germinate in the spring, keep them consistently moist because the young plants are especially sensitive to drying out. Once the seedlings are several inches tall and have developed a few sets of true leaves, you can thin them to one plant per 12 inches or dig and transplant them to the desired location.

Division
The quickest and most direct method of propagation is division. The best times to divide your perennials are spring and fall when the weather is a bit cooler, and your plants aren’t in the middle of their peak growing season. All you need is a spade for digging and some comfortable garden gloves to protect your hands.

Either dig out the entire cluster of plants you want to divide or dig around half of the cluster of plants you wish to divide. Using the garden spade, make a clean cut through the center of the cluster so that each half contains both healthy roots and stems.

Re-plant half of the cluster in the same location (if desired) and transplant the other half into a new location. After getting each half settled and surrounded with fresh soil, water each cluster of plants well to help them overcome transplant shock.

Transplanting
Before transplanting to a new location, first prepare the site. Remove any weeds and other competing vegetation to remove competition. Next, enrich your soil and add any soil amendments, as needed, to ensure that your plants have excellent quality soil in which to grow.

Do your transplanting on a cool day during the spring or fall, avoiding days that are hot, dry, and sunny. Dig a hole slightly larger than the root cluster of your plant. If you are transplanting a potted plant, carefully remove your plant from its pot and immediately place it in the prepared hole.

Fill in around the roots with fresh soil and tamp it down. Finally, water your plant well and keep it well-watered for the first week or so after transplanting to help it settle into its new home.

How to Grow
If you can provide the right growing conditions, this native species is a joy to have in your garden. The most important thing to provide for these plants is rich, moist soil. They are less picky about sunlight; you can grow them in full or partial sun conditions. With ideal growing conditions, you’ll find this lobelia to be easy to grow and virtually trouble-free.

Sunlight
This wildflower performs well in full sun, dappled sun, and fairly heavy shade. In hotter climates, it prefers some afternoon shade, although in cooler climates, it performs very well in full sun.

Water
Lobelia siphilitica is a plant that loves constant soil moisture. Ideally, you’ll want to grow it in a location that is either very close to water, such as at the edge of a wetland, or in a low spot that stays moist throughout the year. Be prepared to offer some regular supplemental watering if the soil dries out.

Soil
Plant in a location with organically rich, moist soil. If your soil is naturally sandy, gritty, or other poor quality, add plenty of organic compost to help enrich the soil before planting.

Climate and Temperature
These plants are well adapted to the warm summers and cool winters of the eastern United States and Canada. The species is hardy in USDA Plant Hardiness Zones 4 – 9. Plants go dormant for the winter months and perform well during humid summers. This is not a desert plant and it would not perform well in arid climates.

Fertilizing
If you have plenty of organic matter in your soil, you shouldn’t need to worry about supplemental fertilizing. If, however, your plants appear weak and the leaves are starting to turn yellow, this may be a sign that your plants need a nutrient boost.

Ideally, add a side dressing or organic compost during the growing season to help improve the overall soil quality. In a pinch, you can add a balanced flower fertilizer. If you use prepared fertilizer products, always follow the instructions on the product label for application and usage.

Maintenance
This is a low-maintenance plant. At the end of the growing season, cut back the dead growth and mulch around your plants to protect the roots for the winter. During the growing season, keep the weeds pulled around your plants to minimize competition. Any time your plants become overcrowded and outgrow their allotted space, you can divide larger clumps and transplant the divisions to new areas.