How much sun do they get? I have some sort of milkweed in a shady part of my yard that hasn't ever bloomed either. It was already growing when we moved in three-plus years ago, and it spreads via the root system, but no flowers.

Martha

Half of them get lots of sun.

Any chance you could post a picture of your milkweed in as much sun as it gets and then a closeup of the leaves? Diagnostics are easier with more information.

Close-up in the sun.

Your internodes are pretty long and it's producing lots of leaves. This species usually blooms in its first year from seed, so since yours hasn't bloomed where it is, it's either too dark, too dry or the soil isn't balanced enough for it. Do they get supplemental water? Fertilizer? Which state are you in?

Here's mine in my hell strip. They mostly bloomed their first year from seed. They also get almost no water but get 12 hours of blasting sun.

We're in NC. Must be the soil although we do use liquid fertilize every few weeks.

I'm in NC, too, and I have little luck with this species although other milkweeds do fine.

What other milkweeds?

I even tried transplanting some Ohio wild milkweeds here unsuccessfully.

A. syriaca, A. tuberosa, A. exaltata, A. variagata. The latter only one plant, and it bloomed this year very well. Here's hoping for seeds! Also have A. verticillata, but so far no blooms from that, as they are very small.

I've been growing incarnate for many years in Michigan and have never had it bloom the first year. I'm betting that is related to my shorter growing season. I would recommend stopping the fertilizer and see what happens.

Martha

Mine were just planted less than a week ago from quart-sized plants and are now blooming. I have Swamp Mildweed (A. incarnate; which seems to be the only one sold around here). They are in full sun to partial sun and the weather has been wet. I was surprised by the blooming given the recent transplanting btw.