White Leaves

Ok so my plants have been doin well but recently I noticed that the bottom most leaves (the first set and the small curricular ones) have begun to turn white and now some have died. Im growing outdoors, in Promix BX soil and have been watering simply when the soil gets dry. The plants are 5 weeks old and for the past 2 weeks the weather here has been overcast or rain so I dont know if that may be the problem, so if anyone knows why this is happening and if I should worry about it please tell me.

plants need n

Mg - MAGNESIUM (Mg)

Lower leaves yellow and may even turn white while veins remain dark green. Blades die and curl upward.

Zn - ZINC (Zn)

White areas form at leaf tips and between veins. Occurs in alkaline soils.

ok well i looked around for a fertilizer that i could use during my plants veg stage and they all said a 20-10-10 ratio or 30-15-15, i looked at 3 different places and was unable to find any fert with this ratio but i did find one that is 30-10-10 is that ok?