Tips To Grow Cardinal Flowers From Seed For A Fiery Garden Display

Cardinal flowers are wildflowers native to the eastern United States. While they are perennials, they're relatively short-lived, so if you opt to buy them as young plants you may be repurchasing every few years — a potentially expensive proposition. Luckily, cardinal flowers can be readily started from seeds, so you can easily and inexpensively replenish your cardinal flowers as older plants fade away. Some of the most important things to keep in mind when starting your cardinal flowers from seed is that they require light and moisture to germinate, have very small seeds, and are heavy feeders, requiring regular fertilizing.

Cardinal flowers (Lobelia cardinalis) are self seeders, so while there are a variety of companies to buy your garden seeds from, if you already have cardinal flowers growing in your yard you can also save their seeds and grow them again. Regardless of how you acquire your seeds, be sure to store the seeds you collect in a cool dry place so they last as long as possible.

Give your cardinal flower seeds light and moisture

The best time to start cardinal flower seeds indoors is generally in early spring, about two or three months before your last frost. Unlike many native wildflowers, cardinal flower seeds don't require cold stratification, so there are no extra steps necessary before planting out the seeds. Simply press the tiny seeds into moistened seed starting mix, but don't bury them. Because the seeds are so small, it's especially important to use a finely graded growing medium.

Once you've sowed your cardinal flower seeds, it's essential that they are placed under grow lights or other good lighting. Keep your germinating seeds in an area at room temperature indoors and make sure the growing medium stays moist but not soggy. Water toward the bottom if possible to avoid disturbing the seeds. Once your seedlings have germinated and reached at least a month old, you can pot them up to give the seedlings more growing space. Around four weeks after that, you should be ready to harden off the plants and transplant them outdoors. 

Fertilizing your cardinal flower seedlings

Cardinal flowers are aquatic plants, and like many aquatic plants, are relatively heavy feeders, so begin fertilizing the seedlings when they are around a month old, using a liquid fertilizer. Make sure you follow the product's instructions to avoid over-fertilizing the young plants. Continue fertilizing every other week until your cardinal flowers are ready to be transplanted outdoors. This bright-red flower can then provide loads of nectar to hummingbirds, especially in the fall.

Be sure to find an appropriate location for your cardinal flower seedlings where they'll receive at least partial sun. Your cardinal flowers should thrive in moist boggy soils along the edges of ponds and can even handle around 3 inches of water above their crown. They can make excellent additions to a rain garden or other moist garden locations throughout USDA zones 3 through 9. Don't forget to collect a few of their seeds at the end of the season so you can start even more of these gorgeous plants.