Fair play to you, from a very modest (admittedly inexperienced) start those plants aren't looking too bad.

Only thing I'd say is your soil mix looks a little 'peaty' and rather dense, what are you using?
For next time you need to remember that typically cannabis plants need a fairly light and airy soil mix to allow oxygen around the root system, otherwise you run the risk of killing the plant if you over water.

A mix of J Arthur Bower's John Innes Number 3 Compost and perlite is an often quoted good starter soil.

As for the yellow spots, I think you need to do a ph test and post the results, I can guarantee you'll get some sound advice on these boards.
Have you read 'Stinky's' - 'simple-noob-instructions-growin-da-dankness' in the 'Basic Growing' section? Sheer genius.

Anyhow, good work and good luck
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