Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
When planning your garden, don’t forget to include cardinal climber vines. Their long throated red flowers attract hummingbirds while their interesting foliage will add texture to your garden.
What are Cardinal Climber Vines?
Cardinal climber vines are annual flowering vines that do not exist in nature. They were created by a plant breeder by the name of Logan Sloter who lived in Columbus, Ohio. He crossed the red morning glory (Ipomoea coccinea) with the Cypress vine (I. quamoclit) resulting in a hybrid he called the Cardinal Climber. Unlike most hybrids, you can save the seeds and sow them the following year in your garden and they will come true. The vine is classified as I. sloteri and looks just like you would expect it to.
Morning glories have heart shaped leaves. Cypress vines have feathery leaves. Cardinal climbers have leaves that look like a mashup of the parents’ leaves. They are triangular with deep lobes that look like palm leaves.
The red morning glory has small red flowers with long narrow throats that are yellow. The Cypress vine flowers can be red, pink or white. The throats of the flowers are the same color as the petals. Cardinal climber flowers are red with long narrow throats that can be yellow or white. The flowers open during the day and close at night. Hummingbirds find them irresistible.
Cardinal climbers prefer full sun. The vines grow to 10 feet in length so they require some kind of support. They climb the support by twining around it so it is important that you provide it with some kind of support that allows the vines to twine around it.
The vines are commonly grown on trellis, arbors, pergolas, and gazebos. You can also grow them in containers provided you give them a trellis to climb on. The trellis does not need to be tall. Once the vines have reached the top of the trellis, they will cascade down over the trellis. For a different look, try growing cardinal climbers in hanging baskets. With no support the vines will gracefully drape over the sides of the baskets.
In the ground, if the vines have nothing to grow on, they will creep along making them a good ground cover.
Cardinal Climber Seeds are Poisonous
You should never eat the seeds of cardinal climbers. They are extremely toxic to both humans and pets. Eating them results in diarrhea and vomiting. The seeds also contain a chemical that is similar to LSD so you could experience hallucinations.
How to Grow Cardinal Climber From Seed
Cardinal climber is easily grown from seed. You will need to prepare it as you would prepare morning glory seeds. The seed coats are hard. You will need to nick it to create an opening for the seedling to emerge. Or you can carefully file it down to create a weak spot for the seedling to penetrate. Or you can use my favorite method which is to soak the seeds overnight to soften the hard seed coat before planting.
Most gardeners direct sow the seed into their gardens when all danger of frost has passed. Before you sow your seeds, set up your support system so that your vines can immediately start climbing it after germination. If you wait until after your seeds have germinated and the vines have begun to grow, you risk injuring or even killing the tender plants if you try to install a support system after the plants have begun to grow. Plant your seeds ¼ inch deep and 6 inches apart. Germination should occur within 10 days.
You can also start your seeds indoors. This is less preferable to direct sowing because cardinal climbers do not like to have their roots disturbed. Your best bet would be to start your seeds in biodegradable pots such as peat pots which you can plant directly into your garden without disturbing the roots. Sow the seeds ¼ inch deep. Germination should occur within 10 days. You transplant your seedlings into your garden after all danger of frost has passed. Plant them 6 inches apart. Be sure to set up your support system at the same time that you are planting your seedlings so that they will immediately have something to climb.
How to Harvest Cardinal Climber Seeds
Despite being a hybrid, cardinal climbers have fertile seeds that will germinate into plants that look like the vines you collected them from. Many hybrids have sterile seeds. Hybrids that do have fertile seeds will usually germinate into plants that do not look like the plants you collected them from or their parents.
Collecting seed from cardinal climbers is easy. After the flowers have died, the seed pods form. Each pod has 2 to 4 seeds. They start out green, but as the seeds mature, the pods turn brown. When the pods are brown, it is safe to harvest them from the vines. Store the seeds in a cool, dark place. I store my seeds in my refrigerator for best results.
Leaving the seeds on the vines to reseed for next year won’t work. The seeds will not survive the winter.
Questions & Answers
Question: Do cardinal climbers need physical help up to attach to a trellis?
Answer: No, they naturally grow looking for something to climb, even another plant. When they find something, they twist around it with no help from the gardener.
© 2019 Caren White
Caren White (author) on August 03, 2020:
My guess would be that either they are not getting enough sun or it is too early for them to bloom. They are related to morning glories which bloom in late summer.
jean shope on August 02, 2020:
I have beautiful cardinal vines that I have grown from last years seed but no blooms wonder why?