no show seeds

hi to all,i seeded about 100 pots about 3 weeks ago in the greenhouse,none have germinated is this par for the course or should i start again,i planted brassicas,beans peas,toms peppers leeks etc .thanks.

Hi Alancas: I won't post the link yet again to the chart which gives very useful information about the germination rates and times for various veg seeds at different soil temperatures in case someone thinks I am either nuts or receive some sort of financial gain from it (I wish!) but if you look in "Growing FAQs and other information" > "Very useful internet links" you will almost certainly find the answer to your question. 

thanks for the info give it a bit longer then hope it warms up soon