1) I have a CA native lily that isn't blooming. I think it may be getting crowded in its pot there is foliage, a bunch 12'' stems but no big flower spike. I wonder if I over watered it this year because it was under the drip in its plastic one gal. a little while in the summer. Do they stop blooming if crowded?
2) I was given a large pot of white easter lilies that my mother in law was given for easter. Its blooms several times a year in its 5 gal pot. I've read that these are unreliable garden plants but this one seems to be quite nice except for the fact that it really has issues with aphids. I am battling them constantly. I grow these lilies is the shade. they are trumpet shaped. I hesitate to plants them amongst the other plants if they are going to breed aphids, but they would look best with some companion plants.
CA Native lily no bloom this year, aphids on Easter lily
I would think they'd both do better planted in the ground. Most lilies resent too much moisture, so that could be the issue with your native one. Many potting mixes are too moisture retentive for Lilies.
Lilies in general are prone to aphid attacks, but I've found them the easiest pest to manage. Typically just soap and water takes care of them. It may be stressed in the pot, and stressed plants are more prone to pest infestation.
I was hoping somene else would answer, because I have very little knowledge about western North American lilies. They are a separate bunch all their own. But yes, lilies in general can become overcrowded and stop blooming as a result. You don't say which species lily this is, but I am guessing that if it has many shoots, then it is one that is rhizomatous. In other words, it creeps in the soil rather than staying in the exact same place year after year. My "advice" is based on this assumption. Being in a pot, it isn't being allowed to creep much and spread as it would want. It's getting bunched up and crowded. This may be causing a short supply of fertilizer too.
Some native California species like to be moist all year. But more like a dry period in the summer after flowering. It's important to know which you have.