Grow Cardinal Flowers from Seeds

Cardinal Flowers are said to be difficult to grow from seed and I was feeling up to the challenge so I collected a few stalks of spent blooms from my garden. One of the hardest parts of growing the Cardinal Flower from seed is just collecting the seed. This perennial flower has very tiny seeds, almost like dust, and often they fall from the plant before they can be collected. I decided to document the seed collection and planting in the video below.

Cardinal Flower

Botanical Name: Lobelia cardinalis

Height: 24-48″

Spread: 12-24″

Germination time: 14 days

Seed planting depth: Surface sow, needs light to germinate

Blooms: Late spring through fall

Attracts: Hummingbirds, butterflies

Description: Features erect, terminal spikes of large, cardinal red flowers on unbranched, alternate-leaved stalks.

Collecting Cardinal Flower Seeds

If you have a Cardinal Flower plant growing in your yard, or maybe a friend has one, you can collect your own seeds. Wait until late fall to collect the seed pods when the flowers have withered and the tall stalks have turned brown. Collecting the Cardinal Flower seeds isn’t extremely difficult but it does require a bit of patience because they are very tiny, almost like dust. Be careful when cutting down the stalks of spent flowers, be sure not to shake it around too much else you might lose some seeds and don’t wait too long to collect the spent blooms either, a strong wind can blow the seeds from the pods.

When collecting seeds from the pods be sure you’re in a location with no wind. Cut the stalks into manageable sized pieces about 4″ long over a paper plate to catch loose seeds. The Cardinal Flower seed pods will be attached to a thin little stem coming off the main stalk.

While holding the stalk in one hand over the paper plate grab one of the seed pods with the other hand and pluck it from the small stem. You’ll likely see seeds fall to the plate below when you do this, that’s why it’s important to do this step over the plate. Now you can crack open the seed pod and gently molest it between your fingers. Don’t worry about getting every single seed out or else you’ll end up with a bunch of chaff on the plate making it more difficult to separate out the tiny seeds.

Once you’ve split open enough of the Cardinal Flower seed pods onto the plate it’s time to separate the seeds from the chaff (non-seed material). Push everything to one side of the plate. Then tip the plate on an angle and shake the plate back and forth, like panning for gold. The seeds will roll to the bottom and leave behind the chaff. Some seeds will be caught in the chaff, just push the chaff farther uphill while continuing to hold the plate angled down, more seeds will roll downhill. Repeat until you no longer see seeds rolling down. Now you’ll have mostly seeds without much extra debris. Any extra seeds can be saved in an envelope, I use little coin envelopes from Amazon.

Planting The Cardinal Flower Seeds

The best way I’ve seen to get the Cardinal Flower seeds to germinate is to use a tray rather than cell packs. Fill a shallow tray with some seed starting mix. I used Burpee Organic Seed Starting Mix, it’s nice and loose and retains moisture well. Moisten the seed starting soil but don’t soak it.

Now just sprinkle the Cardinal Flower seeds around the surface of the soil, use a lot of seeds because most of them won’t likely germinate. IMPORTANT: Don’t cover the seeds with soil, they need light to germinate. Once your seeds are sprinkled on the surface use a spray bottle and mist the surface and place the tray under a humidity dome or in a large Ziplock bag like I did.

The average time for the Cardinal Flower seeds to germinate is about two weeks. Be sure and check on them daily and make sure the soil remains moist. Mist with a spray bottle as needed to prevent the soil and seed from drying out. The humidity dome will have condensation under it when there’s adequate warmth moisture.

If all goes well, you’ll soon have some Cardinal Flower seeds sprouting. Once they sprout wait until they are about 4 weeks old. Gently separate them from the tray with a clump of soil so as not to damage too much of the roots. You can now transplant the seedling into a larger pot, at least 3″ diameter. If some of the Cardinal Flower sprouts are growing near one another just remove them both from the tray in the same clump of soil. Once transplanted let them settle in and see which one grows best, then cut the other off at soil level. Don’t pluck it from the soil or you could do root damage to the desired seedling.

So that’s it, give it a try. If you don’t have access to a Cardinal Flower plant where you can collect the seeds they can be purchased as well for only a couple of dollars. Here are some Cardinal Flower seeds on Amazon.