Hiya I'm new to starting flowers from seed. I've bought a load of Johnsons seed and am having trouble understanding the instructions.

One thing I'm stuck on is where it'll say "cover with .5cm compost" for the indoor sowing but for outdoor on the same seed it'll say "cover lightly with fine soil" Do I still need to sow 0.5cm deep or is it different when sowing outside?

Another thing. It shows an image of a plant with an arrow going up and down with a messurment next to it, that's the plants height but there's another arrow pointing sideways, is that the spread of the plant or the spacing?

Thanks for taking the time to read my post.