Seedlings how deep?

I can't wait to start sowing seeds this year! In fact I haven't waited (I have some grow lights and heat so hopefully it will be ok). I have a question. When I pot up/plant out seedlings like cucumber and courgette, how deep is ok? I know that if you plant tomato seedlings with a fair bit of the stem under the surface then new roots will grow out of the stem and help anchor the plant. Do you know if I can do this with other veggies or could damp earth in constant contact with the stem Cause the stem to rot? Thanks.

 

Thank you JWK, that clears that up. I'm sure you are right about the timing.

 

Hi Altissimo
as JWK said , you need to plant your seeds at the right time . Too early does not help.
There is a large planting guide to download on the site below, like the little picture. It gives you the timing for every vegetable
http://www.thompson-morgan.com/vegetable-seed-sowing-guide

 

Great guide, thank you. I am sure you are right but I thought it might be interesting to experiment with a very small number of early sowings using my grow lights (LED lights which apparently hardly use up any electricity) to extend the daylight hours after dusk until there is more daylight. Also extra protection and warmth. I was sowing broad beans and sweet peas anyway (packets said Jan onwards for indoor sowing). I will sow more at intervals later during the right times and it might be interesting to see the difference all the timings make.