Sumo Gardener

Lobelias | Grow & Care Guide

If you’re looking for a delicate and attractive addition to your garden, patio, balcony or windowsill, look no further than the incredible lobelias. This attractive herb-like species loves to grow in slightly cooler weather and will offer brilliantly colored blooms almost year-round.


Lobelias Grow and Care Guide

With over 400 varieties to choose from, each with its own unique coloring and growth habits, you’ll be almost guaranteed to find a blooming plant just right for you. Want brilliant, true blue lobelias growing at home? Follow our grow and care guide for everything you need to know. 

What are Lobelias?

Lobelias are a must-have springtime plant, well known for their incredible blue blooms

Lobelias are a must-have springtime plant, well known for their incredible blue blooms. These easy-to-grow plants have many gardening applications and were even used for medicinal purposes. 

American Indians have long used the plant to treat lung difficulties like asthma, and varieties like Lobelia Inflata are known to be used in homeopathic recipes. Some western doctors have even prescribed this herb-like plant to induce vomiting, as it is slightly toxic. 

However, if you’re leaving it un-ingested and just keeping it as a pretty perennial in the garden, you shouldn’t have any hassles. It really is the quintessential edging plant.

Are Lobelia Plants Annuals or Perennials? 

This is entirely dependent on which variety you choose to buy. Certain varieties will bloom year-round, whereas some only once or twice a year. 

Which variety you buy will also determine the bloom color; while it’s best known for royal blue flowers, some varieties will also have pink, red, purple and white blooms. 

The most common species used in gardening include: 

  • Lobelia Inflata. Also known as Indian Tobacco, this perennial variety is an upright growing plant with pretty white flowers. 
  • Lobelia Cardinalis. Also known as the Cardinal Flowers, this is one of the most common perennial cultivars found in gardens. 
  • Lobelia Siphilitica. Endearingly known as the Great Blue Lobelia, this perennial cultivar offers the longest-lasting blooms in relation to its counterparts. 
  • Lobelia Erinus. This is the ideal, annual edging plant that grows best in slightly warmer weather.

How to Grow Lobelias at Home

How to Grow Lobelias at Home

Lobelias can be grown almost anywhere and almost any time of year. What’s great is that the lobelia seeds can either be sown indoors in containers or directly into your garden. 

With a fast growth rate, a supremely bright blossom, they’re ideal flower beds or as edging plants, and when planted outdoors, require little to no care. 

The most important factor is to provide your lobelias with plenty of loose, rich, moist soil. As with other nutrient-lovers, it’s always a good idea to add some compost to enrich your soil a week before planting. 

If growing in containers, be sure to choose a balanced potting mix and consider pairing it with some other moisture lovers like violas or sweet alyssum. 

Is Lobelia a Sun or Shade Plant? 

As with most flowering plants, lobelias require quite a bit of direct sun to ensure lots of flowers. As such, they should be grown either in full sun or partial shade. 

However, if grown in extremely hot climates, the sun can cause the soil to dry out too quickly and flowers to wilt. If grown in hot, arid conditions, choose a shadier spot instead, with decent morning sunlight. 

How to Propagate Lobelia Plants

How to Propagate Lobelia Plants

The most effective way to propagate lobelias is from seed, and seeds are usually readily available at most major garden centres. Seeds should be sown in early spring. If the outdoors are still slightly frosty, rather germinate your seeds indoors where it is warmer. 

To propagate, simply:

  • Sprinkle your seeds loosely onto the soil. 
  • Water thoroughly to allow the seeds to lodge. 
  • Store in a warm, humid place to allow germination.

Germination usually only takes about 2 to 3 weeks. Once it’s warmer, you can easily transplant them into your garden. As a rule of thumb, don’t transplant outside until about 8 to 10 weeks after the last frost. 

As these fast-growers easily grow anywhere between 4 to 12 inches high and wide, be sure to space them out. A 4-6 inch distance between each seedling is ideal.

Caring for Lobelia

Caring for Lobelia

Once established, lobelias require very little care, especially if outside. Most importantly, just ensure your soil stays moist and is occasionally fed with some nutrients.

For container growing, never let the soil dry out so much that it starts to pull away from the edges. If outdoors, the natural rainfall should be plenty to keep your lobelias happy. 

If it’s a particularly hot or dry season, supplement with bi-weekly watering. Use a multi-purpose, slow-release fertilizer every few months to help keep your plant well-fed and happily growing. 

It’s recommended to mulch your soil during the spring and summer months and avoid altogether in the wintertime as it may cause root rot. 

What do you do with Lobelias After Flowering? 

While your lobelias won’t need pruning, it is a good idea to prune back flowers once they begin to start seeding, as this will help to stimulate new flower growth in the months to come. 

If you notice that your blooming has begun to slow, perhaps because it’s too hot, consider cutting back as much as a third of the plant to help it bounce back in the next blooming season.

Problems, Pests & Diseases

It is unideal to grow lobelias in high heat, and this will often lead to issues. If you’re wondering why your lobelia might be dying, it could be that your soil has dried out, and your plant is unable to get the nutrients it needs.

Always be sure to keep your watering consistent. The only other issue you may have with your lobelia is the invasion of aphids, slugs or snails. However, a great way to deter slugs and snails is through the use of coffee grounds.

Gardening Applications of Lobelias

Gardening Applications of Lobelias

There are so many ways you can use these beautifully blooming plants. Not only are they hummingbird havens, but they’re also fantastic pollinators. Plus, you can find varieties that are upright growing, trailing, half-hardy, create shrubs and even some aquatic species that favor marshy conditions.

Grow your lobelias:

  • As part of a ground cover. 
  • As a border plant. 
  • As an edging plant
  • In Woodland Gardens. 
  • Or even in patio planters and window boxes.

Wherever you decide to plant them, they’ll be guaranteed to add a splash of colour. 

Final Growing Tips for Lobelias

  • Lobelias are a hotspot for butterflies, so pop a planter onto your patio or balcony in a hanging basket to attract lots of these pretty daytime visitors. 
  • Lobelias are non-invasive and are great when paired with other flowering flora such as pansies, geraniums and daisies. 
  • Lobelias function well as filler or spiller plants. Just be sure to choose the right variety for your growth needs. 

Wrapping Up our Grow & Care Guide

Follow these tips, and you’ll have plenty of beautifully blooming lobelias growing at home and if you’re looking for some pretty partner plants, check out some of our other flowering plant guides here

Lobelias really are all about the colour, and depending on which variety you choose to grow, you can have those gorgeous blooms almost year-round.

Check your soil regularly to make sure it’s maintaining enough moisture for optimum growth, and cut back flowers once they begin to wilt. Now you can start growing lobelias in your garden! 

About the Author Ann Katelyn

I'm Ann Katelyn, Creator and Chief Author of Sumo Gardener. Since I was a child I've always been fascinated with plants and gardens, and as an adult this has developed into my most loved hobby. I have dedicated most of my life to gardening and started Sumo Gardener as a way to express my knowledge about gardening with the hope of helping other people's gardens thrive.

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