Growing Lobelia: A Ultimate Care Guide

Last Updated May 16, 2022 By Bella Zinti

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Are you looking for an easy-to-grow flower that will give you bright blooms right until the first frost? Look no further than lobelia! This is a vibrant, annual herb that's available in many varieties and colors. It doesn't need to be deadheaded, which means it keeps a neat appearance. Below, we'll talk about everything you need to know to grow and care for lobelia in your garden.

What Is Lobelia?

Lobelia (genus Lobelia) shoots up a tall stem that reaches anywhere from 5 inches to 5 feet tall and is covered in small hairs. Clustered around the base and continuing along the length of the stem are serrated, oval leaves. The flowers also go up the length of the stem. They have three distinct lower petals, drawing pollinators into the tube at the base.

Lobelia is a perennial in USDA zones 10 and 11 but can be grown as an annual in cooler zones. Its native plants to the marshlands of Central America and parts of North America, where it is used for medicinal herbal remedies. It's also native to southern Africa, and it's available in multiple varieties. Some of the most popular are:

Lobelia inflata (Indian Tobacco)

This 2 feet tall lobelia plant has pale purple flowers with a tinge of yellow. Native Americans would smoke lobelia inflata leaves to treat asthma, giving it its nickname. It would also be used to induce vomiting, and so is also sometimes called "puke weed."

Lobelia cardinalis (Cardinal Flower)

The blooms of the Cardinal Flower are a brilliant red. This lobelia variety, also called Indian Pink, will reach 5 feet tall and can handle brief periods of flash flooding. It's often planted in wet meadows or rain gardens, and it's very attractive to hummingbirds.

Lobelia siphilitica (Great Blue)

The flowers of this lobelia variety are a bit larger than others, and the plant can reach 4 feet in height. The bright blue flowers have pale stripes on the bottom petals.

Lobelia Care Requirements


Lobelia needs plenty of sunlight, and it does well with anything from full sun to partial shade. However, it does not like direct sunlight during the hottest part of the day. If you live in a cooler zone, make sure that your plant receives at least 6 hours of sunlight a day. If you live in a hotter zone, pick a location where the lobelia will be shaded during the hot midday sun.


Lobelia is a low-maintenance plant, but it does require plenty of water. It is native to American marshlands and grows well in wet conditions. This does not mean that it should be overwatered, particularly if grown in a container, but it's important not to let the soil dry out completely. During dry spells during the summer, water your lobelia frequently.


Frost will kill your lobelia, but too high of temperatures will cause it to stop blooming or dieback. Don't worry too much if you notice your lobelia struggle during the summer heat. It may cease blooming, but when the temperatures start to become milder in autumn, you'll see the colorful flowers again.


Lobelia enjoys humid conditions. If you keep it well-watered, there will be enough moisture in the air surrounding the plant to keep it happy.


Plant your lobelia in rich, well-draining soil for the best results. You can boost it by mixing some compost into the soil directly before sowing the seeds, and slightly acidic soil is best.


Although it's unnecessary, feeding your lobelia with a general-purpose liquid fertilizer every month will keep your plant healthy and boost the number of flowers it sets out.


Lobelia is propagated almost entirely by seeds, particularly where it is grown as an annual. You can sow the seeds directly into the garden after the threat of frost has passed. You can also sow them indoors, about 10 to 12 weeks before the last frost date. Lobelia seeds don't need to be planted deeply. Scatter them across the top of the soil and give them a good watering. Keep the soil moist. You'll notice seedlings in a week or two, and then you can start thinning them out a bit.

Common Problems

The most common issue with lobelia is browning. Lobelia will naturally brown a bit during the summer heat, but there are other reasons you might notice your lobelia turning brown.


Rust is a type of external fungus which usually starts on a plant's leaves. You will notice orange and brown spores. Remove any diseased leaves and treat the plant with a neem oil spray. This fungus tends to spread if the plant lacks good air circulation. You can prevent rust by making sure that the area around the lobelia is not too overgrown.


Mites suck the juices out of leaf cells, causing them to die. This creates tiny, brown spots. Given enough tiny brown spots and the whole leaf will look brown. Spray the mites with neem oil or an insecticidal soap every week until the new leaves remain green.

Corn Earworm

These larvae burrow into the base of the stem and eat it, hollowing it out completely. Once a larva is inside, it's hard to do anything to stop the damage. You can prevent larvae from burrowing into your lobelia by spraying acephate around the base of the stems.

Is Lobelia Pet Friendly?

No, lobelia is not a pet-friendly flower, and it's poisonous to both cats and dogs. You will notice symptoms of abdominal pain, drooling, diarrhea, depression, dropping ears, heart arrhythmia, and nasal drippage.

Health Benefits of Lobelia

Lobelia is a flowering plant that is often used to make medicine. Some studies show that lobeline, the active compound in Lobelia inflata, may help treat asthma, depression, ADHD, and drug addiction.

Lobelia contains a chemical that is often used in alternative and complementary therapies. The chemical may thin mucus to make it easier to cough up and help to breathe. Some studies suggest people with asthma can benefit from taking lobelia. However, high doses can be toxic and have serious side effects.

One of the chemicals in lobelia is very similar to nicotine, and some consider it a tool for smoking cessation. However, there is still a lack of evidence about its efficacy, and it will not help people quit cigarette smoking or chewing tobacco.

Lobelia can also be applied to the skin for muscle pain, bruises, sprain, insect bites, poison ivy, and ringworms.

Who Should Avoid Taking Lobelia

Don't take lobelia if you are pregnant or breastfeeding. Also, avoid the herb if you have stomach or intestinal problems like ulcers, Crohn's disease, inflammatory bowel disease, or intestinal infections.

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About the author

Bella has a Bachelors degree in interior design, is a master gardener. She designs nourishing outdoor & indoor spaces guided by the practice of Feng Shui.