How much sunlight are they getting? How tall are the plants?

Wondering if they are stressed due to light or soil issues. Since you are in Washington, it shouldn't be the temperature.

Peas don't really require a very fertile ground - much like green beans.

Here is a link that might be useful: My Garden Blog

Hi bsntech, my box is in a sunny spot, but we have a lot of rain and mostly cloudy days. Last year I had similar problems but the box was in a shadier spot. I thought more light might help (not just with peas but all the plants)The flowering peas are small, no more than a foot tall. But they're flowering-I've even got a few peas developing! But those plants certainly won't produce much. I thought that perhaps they were getting too much water from all our rain because they were yellowing and looked like they were dying. We had a couple of drier weeks and they did pop back to green but they are so small and the bottoms are all dried out and leaves brown. Tops look healthy. All the rest of my peas are either pale, limp and yellow, or their growth seems to have halted. Some of them are only a few inches tall and have been that height for weeks My lettuce isn't growing well either. Nothing is to tell you the truth! Could it be my soil? I used mel's mix...

I delayed planting peas this year because we were still getting frost until about a month ago. I'm on the Kitsap Peninsula. However due to the fact they did this to you last year; it wouldn't be the temps. You might want to check with a local Master Gardener or the county extension service

But can't peas tolerate frost? We've had some late frosts here too but I didn't think that would effect peas. Maybe I planted them too early last year too. Last spring was as bad as this year's.