Q.My leucanthemum won’t bloom
Last summer I picked up a leucanthemum at Home Depot toward the end of the season. There were three plants in the container. I separated them, transferred one to a larger pot, and planted the other two in the ground. All three returned this summer with abundant foliage, but no flowers. NONE! What happened?
Most likely to much Nitrogen in the soil.
You can add Phosphorous which will promote flowering.
Bone Meal is a good way to do that.
Here is a link with more information.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/bone-meal-fertilizer.htm