Nightmare! Why are my marijuana leaves brown and drying out?

Tips, Tricks

1. straight up is wind burn
2. it's very hard to say what happened here without knowing a lot of other factors but my best guess because you said you did water right before that happened. So my questions would be are you sure it needed water? Did you add nutrients to the water? it doesn't look like wind burn or anything like that to me and it's too fast for something like that to happen that dramatically. I'm leaning towards it's some kind of deficiency or over-fertilization. like I said it's hard to really pinpoint it but it's not lack of sunshine if it happened all of a sudden like that. Sunshine or light whatever. I see a lot of people saying it's lack of light and this is normal but if it just occurred that fast it's definitely not light. It doesn't even look like a light issue to me. It looks like the plant is cannibalizing itself honestly. I would say could be lack of nutrients except for the fact that the rest of the plant looks extremely healthy. I'd say maybe that strain doesn't like a lot of water. I would also ask you if you know which strain you are working with. A lot of strains do not like a lot of water and react quite similar to this period for a few years I had something similar but not as bad happening and I could not figure it out because it was not happening to all of my plants only a select few and I was doing the exact same things as I have done in previous years without any problems. It turned out that I accidentally use the mystery seed and I did not know what the strain was and when I start to let the plant go very dry it did a lot better than most plants do by watering normally
3. its normal bro, as long at the tops dont bend over and die your fine
4. I'm looking for free seed
5. Cannabis is a nightmare in itself. Maby you got the wrong seeds
6. I'd go through trim some under unneeded leaves so you get a even amount of light through the canopy!I've seen that happen from the wind or a fan dozens of times as well? you want to run a fan onver the top of your canopy kind of grazing the top of it..and I really don't be scared to take some leaves the I really believe aren't going to do much good!if anybody disagrees with me I have no problem with criticism and would love to hear it... Happy growing
7. windburn
8. that looks like the start of verticillium wilt m8
9. Really bro that sound doesn't have to be in that long 
10. maybe to much feeding 
11. Little light*
12. And for the record you can have plants getting very little little and if the plant is fed perfectly those leaves at the bottom will remain green! The reason they change colors is because the plant is taking the mobile nutrients from it (not all nutrients are mobile once stored).
13. I would also like to add that Too much of the following can lock out magnesium: Potassium, Calcium, Manganese (rare and unlikely), and excess sodium (common with synthetics, uncommon with organics). 
14. No, that is 100% incorrect. Those leaves there are 4 nutrients that cause problems that start at the bottom (there are also other problems but I do not see that here from this limited info), they are: Phosphorus, Nitrogen, Magnesium, and Potassium. Phosphorus will cause the top petioles to turn purple (just worry about the top couple the rest can be purple and that is fine, and that's an early warning sign FYI), K (potassium) will cause stem striping before it's a big deal. Magnesium FTW.
15. i am having this issue right now in a DWC set up, and the fan is kinda close. i moved the fan 2day now i am going to see if that helps. this is my 1st grow so i am asking ppl what i should do
16. NA tht looks almost like mites or somtin
17. It's normal proberbly. It,s different from strain to strain. Some throw their leaves 1-2 weeks into flower,and others later or almost none at all
18. its too much wind...
19. Hey man, did you ever figure it out? 
20. its normal, the leaves at the bottom are not getting any light. so the plant eats them up. dont wurry bout it