Hmmmm Brown crispy leafs not good!!!!

Hey peeps wondering if any one can help me out here... This is my first soil grow as i lost my genetics and am having to start a fresh from seen so i figured stick them in soil any way there about 3 weeks in and the botom leafs are turning brown and very crispy...

Im not feeding them with anything as of yet but i was gona start with a weak hydro veg solution... will that be ok???

Any way ill put a pic on so u can have a look at this leafe browing..


oh yeah by the way the plants were in 3" rockwool cubes when i placed them into the soil... is this gona be a problem???