Posted: 01/04/2015 at 06:36
John I'm getting confused by what is happening.
From what I understand you are sowing seeds in two different batches of soil - some are in a proprietory store-bought compost and others are in soil that you've brought inside from your garden.
What varieties of seeds are you sowing and in which soil?
Are the seedlings dying while they're still indoors, or after they've been hardened off and planted outside?
If I'm correct in thinking that the seeds raised indoors in garden soil are dying off after transplanting outside, my thoughts are that the garden soil is too rich and the seedlings are growing too lush and soft and are consequently burning in the sun when planted outside, even when an attempt has been made to harden them off.
Proprietory seed compost is low in nutrients because this is what seedlings need - it's only later on as they grow that they need higher levels of nutrition.