Q.Forsythia not blooming
Forsythia not blooming, or very few at base of shrub. I am in Cameron, MO – 5a zone, shrub planted between my home and neighbor’s with plenty of room around it. Sunshine should be no problem as it gets east and west sun. I planted it about 3 years ago and it is growing, as I check branches and they are limber. I haven’t pruned it since purchase. Should I, and when?

There are a couple reasons why your forsythia might not be blooming.
With the harsh winter we all have been having, are you seeing winter kill?
Perhaps your plant does need some pruning since it was planted 3 years ago. Blossoms form on 1 year old wood.
Here is a link to help you pinpoint the issue further.
https://www.gardeningknowhow.com/ornamental/shrubs/forsythia/forsythia-not-blooming.htm