I have a small urban garden, so I like to start my vegetables in pots
and then transplant. I am having a terrible time starting spinach. I
use commercial potting soil and mix in a handful of manure, wet the mix
and fill the pots. Then I add two seeds to each pot. Within two weeks,
everything sprouts, except spinach. I get one or two plants out of the
12 seeds every time. I have tried several brands of seeds. Same
results.

Any suggestions?

TIA
Mike