nothing seems to grow properly

Peas and beans I always start off in seed trays to stop the mice and other such pests eating them before they are rooted.

Cabbages, cauliflowers, sprouts, broccoli and kale I always start off in seed trays and move on to pots so that they have a really good root on them when they go into the soil.

Now these are the brassica family (and swedes, kohl rabi and beetroot are also brassicas). I've been taught to add lime to the soil here to sweeten it a bit (clay you see) and to feed the soil heavily before I plant them out. I've also been taught to tamp the soil down very firmly just before planting as these plants don't like to rock in the breeze. But all of the group including those in brackets need to be watered regularly if it doesn't rain.

Now the allotment association secretary has had me in hand with this family and I am now doing well. So I suggest that his advice would be good to follow for you too. See - the seed packet is sometimes not as detailed as it might be due to the size of it.