starting seeds

[curlysue]

when is the best time to start seeds indoors in zone 5B

[growitall]

It depends on what you are growing. If it's annuals that need to be started early indoors due to a short season (or if you choose to start them early for earlier bloom), then usually 8-10 weeks before your usual last frost date.
If you are starting seeds that are more complicated (certain perennials), the process may best be started many months before your last frost date.
It would be best if you listed what you are growing.