Garden Q&A: Cardinal flower has much to offer
Q: I would like to know how to propagate cardinal flower. Thank you.
A: Cardinal flower — Lobelia cardinalis — is a native of North America and is a terrific plant for gardens in Western Pennsylvania. It reaches about a foot and a half in height and bears spires of bright red flowers that are extremely attractive to hummingbirds.
Cardinal flower is very easy to grow, preferring afternoon shade and average garden soil. It does very well in damp, poorly drained soils and is deer resistant. There are numerous named cultivars of this plant that are common in the nursery trade, and a similar species — Lobelia siphilitica — bears tall blue flowers in the same fashion as its cardinal-colored cousin.
Cardinal flower is best propagated via crown division. As the plant grows, small daughter plants form to the side of the mother plant. These young plantlets are easily dug up and separated. As this is a fairly quick growing plant, you'll be able to separate the daughter plants every two to three years. It is quite possible to readily establish a nice-sized colony after only a few year's growth.
It also is possible to propagate cardinal flower from seed. Seeds ripen in the fall about two months after flowering. Harvest the seed capsules before they fully brown and crack open. The easiest way to do this is to invert a dry flower stalk into a brown paper bag and wait for the capsules to naturally crack open. Their seeds will then fall out into the bag. Each capsule contains many seeds, so any seeds you don't harvest will drop to the ground in autumn and naturally colonize.
Alternately, if you don't want an entire stalk of seed pods, crack off just a few of them and let them sit on the kitchen counter on a coffee filter until they naturally crack open and the seeds fall out. The seeds do not need to be exposed to a period of cold before they can germinate (a process called stratification), but if you want to delay planting them until spring, place the dry seed in a sealed container in the fridge until planting.
Come spring, sow the seeds in new, high-quality seed-starting mix. As the seeds of cardinal flower need light to germinate, surface sow them and do not cover them with more soil. Keep them watered and place them under grow lights for 18 to 20 hours per day. Germination will take place in two weeks to a month.
Plants grown from seed will often not flower for two or more years, while those grown from crown divisions are quite capable of flowering the following summer.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio. She is the author of several gardening books, including “Grow Organic” and “Good Bug, Bad Bug.” Her books are available at her website, www.jessicawalliser.com.
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