I started a dozen echinacea seeds indoors about 5 weeks ago. 11 seedlings germinated and are now in 3" pots and about 2" tall with 1 prominent true leaf growing and a second just starting. I am still a bit of a novice and didn't know about cold stratification before planting, so the seeds didn't go through that process. While they showed a good pace of growth initially, they've slowed and stayed the same height and had very slow development of a second true leaf in the past 10 days. Wondering if lack-of-stratification is to blame or perhaps something else? They're getting about 16 hours of light a day between grow lights and protected outdoor patio light (it's warmed up enough to have them out).
Any thoughts would be greatly appreciated! Thank you.

Your plants look okay. Just make sure to give them steadily more sunlight as you prepare to move them out permanently. It is very common for seedlings to appear to stall and then suddenly grow more because we cannot see root development or stuff happening at the cellular level.

Cold stratification is a method of inducing plants to sprout. In plants that need it, cold stratification increases the germination rate. Once the plants have sprouted it does not affect their growth. 11 of 12 seeds is a good ratio.

You need to let the soil dry between waterings very well. If you keep the soil wet the roots won't grow large. If you allow the soil to dry the roots will grow down looking for water. So give your plants a wet to dry cycle like mother nature does for best results.

They need some warmth and some sun, lots of sun. I would get them outdoors on a patio or something or get them in a good container. They will easily over winter.

ActionVerb, I'm so glad you asked this question because my Echinacea Purpurea seedlings I started from seed in March are doing a similar thing. It's the middle of May now, I moved them into 6 inch pots in April, they are getting full sun everyday and I'm being careful about over watering but they only have four leaves, the main sail, a small secondary and the two baby leaves and I'm starting to get concerned. Did yours eventually get a growth spurt? How big were your seedlings before you put them in the garden? I hope you had success so that you can share! Thanks so much.

@ArtandFlowers
The OP only posted that one time 4 years ago so may not reply.