Hello, I recently purchased some Cardinal flower seeds and would like to plant them. The seed package doesn’t include much instructions other than spring sowing. I noticed online that some other sites recommend chilling the seeds in the refrigerator prior to planting. Is this tactic necessary or could I direct sow with success? Thank you.
Thank you for contacting the Toronto Master Gardeners.
Not only is Cardinal Flower (Lobelia cardinalis) a beautiful perennial but it is also native to North America and a favourite of pollinators like hummingbirds and bees. So it’s a win-win choice for you and your garden! One important note is about safety though. Both the seeds and plants of Cardinal Flower are very toxic to humans and pets if ingested as described here in these articles from North Carolina State University and the American Society for the Prevention of Cruelty to Animaks.
Cardinal Flower is one of those perennials whose seeds require cold stratification which means that they need to experience a period of cold temperatures before they can germinate. This process mimics the conditions that the seeds experience in the wild. The Plant Native is an informative website and outlines easy to follow directions about growing Cardinal Flower from seed. To summarize, there are two ways to grow Cardinal Flower from the seeds you purchased.
- In the fall the seeds can be planted directly in your garden by sowing on the surface of the soil as they require light for germination.
- Or, begin the process in the spring. The seeds need to be stored in the refrigerator or unheated garage for 30-60 days and then planted indoors 6-8 weeks before the last spring frost. Once there is no longer any danger of frost, they can then be transplanted into your garden. In Toronto, the last frost date typically falls between May 4 and May 11. So counting backwards from May 4, seeds can be started indoors in mid-April following a period of cold stratification beginning in mid-March. Please see The Spruce, another informative website, for more specific directions if you plant to start the process next spring as Cardinal Flower requires specific light, water and soil conditions to be successfully started indoors.
I wish you every success with this project and please do not hesitate to reach out again with questions in the future.