More or less remote resemblance will be: Silene regia and Lychnis chalcedonica(color), provided you'll find non-flopping clones.

Lobelia cardinalis is a short-lived perennial even under the best circumstances, so 2-3 years is a normal lifespan. The best bet is to let them seed in order to get new plants. They are fussy about overwintering -- they hate wet winters and mulching over the basal foliage can kill them. Not sure about the bloom problems, but they like plenty of sun with moist but well-drained soil. They are recommended for part sun because full sun tends to dry the soil out too quickly.

Silene and Lychnis also relatively short-lived as well.

Lychnis chalcedonica is not short-lived here. Mine are at least 9 years old and not slowing down. Short-lived lychnis are: Miquelliana, coronaria, Arkwrightii , cognata(impossible to keep alive) and flos-jovis.

Yes, chalcedonica does tend to be longer lived than the other Lychnis species. An excellent selection - -though that one is the exception rather than the rule for Lychnis. I don't shy away from growing something because it tends to be short-lived. Just gives you an excuse to buy something new and exciting after a couple years.

If you have one of the cultivars of Lobelia cardinalis with dark foliage, then it could be that it is more short lived than usual or not hardy in your zone.

I have 4 or 5 large clumps of regular L. cardinalis with the green leaves. The oldest 2 plants were purchased in 2007 and are still going strong so for me they are truly perennial. I also winter-sowed some and they reseed here and there, like along the edges of paths.

They like part-sun, moist rich soil (most of mine are in a lasagne bed), and I also deadhead all but a stalk or 2 for collecting seed. This means the plant will put its energy into establishing offshoots for the fall. Apparently those offshoots are what continues onto the next year. A little compost in the fall seems to help too.

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I also have several clumps of L. cardinalis, the straight species with green leaves, and they have been there for many years--at least 7 or 8,in full sun and sandy soil. I think the cultivars with dark leaves may be much fussier plants.

It is often hard to tell whether they are coming back from the roots or volunteers. Either way, I love the looks of these planted en masse like that pic from terrene. I planted some 'Complement Deep Red' this year which is a species mix of siphilitica, cardinalis, and fulgens. So far, they look vigorous -- strong thick stems that may not need staking and good sun tolerance. Don't give up on them!

Mine are definitely coming back from the original plants. However, they make "offshoots" or "offsets" in the fall, and that is what actually overwinters. There is a great explanation about Lobelia cardinalis and the way it winters over in William Cullinas book on Wildflowers. It is one of my favorite books and will type an excerpt:

"Lobelias are not true perennials, because the flowering stem and its associated roots die after setting seed. They are perennial in effect only because new offsets grow from the axils of the lowermost leaves and quickly put down their own abundant white roots. It is especially important, then that these new offsets be coddled a little in the fall. Think of them as seedlings that must be kept free of debris and competition so that they will have a chance to establish roots before winter. With a little attention, the plants will come back indefinitely."

That is why I dead head these plants, including removing the seed pods as they are forming and even before a stalk has finished blooming. I want them to establish healthy offsets for the winter.

Would Antirrhinum 'Black Prince' be a suitable substitute?

Here is a link that might be useful: Antirrhinum 'Black prince'

Terrene, your Lobelias are just too wonderful! Now I have to try them again. Could you give details about your lasagna bed? What exactly did you use for the layers and how long did you leave it to "bake" ?

Wow, terrene, I definitely learned something from that. I will deadhead mine as well and hopefully get some good offshoots. If you deadhead, will the main stem roots still die? Is there any other advice for getting these to survive the winter?

As for the snapdragons, flora, I do not think they survive hot, humid U.S. summers well, but that cultivar you mentioned stopped me in my tracks this Spring.

As you all know there really isn't any substitute for Lobelia cardianalis...it is a wonderful plant. I also find all the info above very interesting. My contribution is a few suggestions based on some of Lobelia's different features. If you want something drop dead red and attractive to hummingbirds you could try Crocosmia Lucifer. It is a small bulb that will multiply. The flowers are gorgeous bright red also. Another red flower that grows on a stalk would be a bright red Gladiola. I'm not sure if either of these might be easier or better for you to grow but they each have their advantages! There is also all the hummingbird salvias which will bloom all summer like Lady in Red or Texas Hummingbird sage. Also the red salvia greggii are also wonderful!
Joann

I don't know if the main stem always dies. All I do is diligently deadhead and give them some compost approx. once per year. You can leave a stalk or 2 if you want to have seed, because it makes a zillion tiny seeds in each pod (similar to Foxglove). Actually, I do the very same thing with Digitalis purpurea, and sometimes get a 3rd year out of that biennial.

That lasagne bed was made with a layer of cardboard, an inch or two of coffee grounds, a layer of leaves, and a bit of other misc. organic matter. It was not very deep - maybe 3-4 inches. I created it over the summer and fall, mostly to kill the Vinca and weeds underneath, and started planting the next Spring. The bed got even better the next year or two as the organic matter continued to decompose!

Everything in that bed grows really well - except for Foxglove - one year I had HUGE beautiful clumps started from seed and the crowns just rotted over the winter. Too rich and moist I am guessing?

I just love Cardinal flower and it is also the hummer's favorite, at least in my garden!

Thanks for the suggestions, folks. :)

They give me some food for thought.