If they are rootbound or even not quite rootbound but choking themselves the plants could be stressed and reserving their energy just to sustain life rather than setting blooms.

I would uproot them, wash off the roots and detangle them to be sure they can spread properly and then replant in the ground or in a wide AND DEEP pot. Give them some time to de-stress and THEN get a fertillizer/food to feed them. If you feed while the plant is stressed this will be no good. Get the plant feeling better, settled and THEN start feeding.

Hope this helps.

Barb
southern Ontario, CANADA

Sweet violets only bloom in spring so you should not have seen flowers last summer and fall. They are perennial and many perennials do not bloom much their first and second season after planting. If light green, not dark green they may need feeding or more sun.

Possibly there is too much shade, as they grow in sun or partial shade. Give them another year, especially if you can put them in the ground.

Here is a link that might be useful: Sweet Violet Info