Skip to Content

How to Grow Lobelia

If I had to pick a favorite flower, lobelia might be it. The intense blue of this dainty-looking annual flower adds a lovely pop of color to raised beds and containers. Lobelia blooms are a profusion of small tubular flowers that come in blue, white, magenta, or purple. These four tips teach you how to grow and add lobelia to your garden or containers. 

How to Grow Lobelia

Disclaimer: This post may contain affiliate links. See my disclosure policy for more information.

4 Tips for How to Grow Lobelia

Lobelia, blue salvia, and artichoke
Lobelia, blue salvia, and artichoke

1. Grow lobelia from seed or transplant

Start seeds indoors 6-8 weeks before planting outside. Press seeds into the soil but do not cover; they need light to germinate. 

When buying transplants, look for compact, healthy transplants with few blooms, stocky stems, and deep-green leaves. Avoid plants with faded flowers or yellow foliage. 

Varieties to try: 


2. Plant lobelia at the right time

In most locations, plant lobelia transplants in the spring after the danger of frost has passed. Lobelia blooms from early summer through the first frost in places with mild summer climates. After frost, pull up the dead plants and add them to the compost pile. 

Plant lobelia from late September through December in hot summer climates. Lobelia blooms from early spring until temperatures soar in June. Plant lobelia in shady locations to keep lobelia alive longer. 

When to plant lobelia in Arizona

Start seeds indoors:
July – October
Plant transplants outside:
September 15 – December

Lobelia at the end of raised bed gardens
Lobelia at the end of raised bed gardens

Perpetual Flower Planting Calendar for Zone 9B

Flowers to Plant Outside & Seeds to Start Indoors Each Month in the Low Desert of Arizona.
PLANTING GUIDE: Each month lists annual flowers and bulbs to plant outside & seeds to start indoors.
BLOOMING GUIDE: Photos show what may be in bloom that month.

3. Plant lobelia in the ground or in containers

Lobelia plants are 4-24” wide and 4-8” tall. They are an excellent choice for tucking in around other larger plants and the outside edges of raised beds and containers. Lobelia’s compact size makes it a perfect choice for growing in containers.

Lobelia, blue salvia, and foxglove
Lobelia, blue salvia, and foxglove

My favorite plant combination is lobelia, planted with blue salvia. They look so good grown together. I find myself adding that combination all over my yard.

  • Lobelia prefers moist, rich, well-draining soil. Amend the planting area with compost before planting.
  • Choose a location with partial sun (4-6 hours); morning sun is ideal.  
  • Mulch plants well after planting to conserve moisture and keep the soil cool.
  • Feed with a fish fertilizer after planting to encourage growth and blooms. 
  • Shade newly-planted seedlings for the first several days.
Lobelia with blue salvia and a potted fig
Lobelia with blue salvia and a potted fig

4. Care for lobelia as it grows

  • Lobelia can become heat-stressed during hot spells. Give plants additional water. 
  • Cut back spent blooms regularly to encourage more flowers. 
  • All parts of lobelia are poisonous. Keep plants away from pets and children. 
  • Allow the plant to drop seeds, and it may reseed the following season.
  • If you use lobelia as a cut flower, hold the stem in a flame for 15 seconds immediately after cutting to seal the latex in the stem. This prevents the sap from leaking into the water (shortening the vase life) and keeps the water-conducting vessels open.
How to Grow Lobelia
Lobelia and freshly-harvested golden boy beets

If this post about how to grow lobelia was helpful, please share it:

Molly Milano

Sunday 7th of August 2022

I just ordered some seeds : ) can they be started directly in the garden or do they do best when started indoors ? Thank you

Angela Judd

Sunday 7th of August 2022

Lobelia does best when started indoors.


Friday 5th of August 2022

Love this! Thank you

Laurie Farricielli

Monday 1st of August 2022

Always enjoy your information!!

Angela Judd

Monday 1st of August 2022

Thanks so much!