You don't mention whether you sow inside or outside.
I find that starting them off in cells/pots the germination results are higher then station sowing. The reason being, temp, water and heat can be controlled better, especially in cooler climates like the UK - this goes for peas also.
I have, in the past, always had more failures than successes when using the station sowing method...
.....not sure if I've helped much !!! !