leaves became white and dry..what to do?

hi
i'm a first time grower,I planted a few plants in my garden about a month back. they looked great untill a few days ago when the leaves started showing white spots on them, and the stems changed from green to red-like color (a picture is attached) mainly on the lower parts of the plant.
what do you think is causing that?
i'm using regular (bought) soil, no nutrition, don't know what the PH is. the plants get about 8 hours of sunlight a day, and plenty of water.
(i live in a desert-like climate - hot days and cold nights - can this be part of the problem?)

anyway, i'l be glad to hear what you all think,' i'm stuck and i realy don't want to see all of them go to waste.
Attachment 295822

it looks like a bug, leaf miner. The plant isn't in the best situation to promote good health and growth. Unlike most house plants, cannabis is basically an outdoor plant and likes lots more light, quality soil or supplemental nutrition and proper pH.

Red stems are normal. Bug is a leaf miner of some sort. Remove the infected leaves. Bugs are actually helping by directing you to remove leaves blocking light and air to lower parts of the plant.

thanks for the help!
do you thing neem oil will help with that?

i'l try another question while i'm here:
i planted my seeds about a month ago, i know it's not the time to plant but the temperature here is about 70 F most days, sometimes even more. (and if it won't work - at least it was a practice run)
BUT, the days are allready short. how, and when, can i get my plants to flower?
i'v looked everywhere but didn't find anything about growing outdoors at this time of year

thanks a lot for all the help