first time growing. i need help!!!

hi, ive just recently decided to start growing my own weed, obviously! i went shopping and the guy gave me a package deal of 1x20l nft, 1x600w hps, optimum grow a and b and optimum bloom a and b. im growing A.M.S in my cupoard which is about 7foot wide but only 1-1/2 ft deep. the seeds germinated quite slow with taking just over a week. it is two weeks since i placed my plants into the nft tank after them having a decent enough root system. i read that plants can grow fine during vegetation with 24hr lighting (an option i thought i should take as its -1c outside!!) my grow room is 30c at the moment and i have a fan running slow to improve circulation.
now comes the problems.........
as you can see in the pictures ive posted, some of the older growth especially at the bottom of the plant but also at the top is turning yellow and drying out. my light is about 3 1/2ft away from the tops of my plants, there is also i have noticed on one of my plants, the main stem at the bottom has some sort of black rotting on it, ive touched it and its hard but its discoloured and turning black, only on one tiny bit of the stem though. the leaves seem to be drying right out,some going brown and some going yellow. i have recently had my first water change and the plants all dramatically wilted and the leaves dropped. ive read that it can be normal for plants to discard the yellowing leaves but they still seem quite strong at the branch if that makes sense. can anyone help me and?! im currently running the cycle of nutrients as advised on the bottle which is 3.5ml/litre water of each a and b for both grow and bloom. any help would be greatly appreciated as im trying not to panic because its my first grow. thanks!

i should also add im using rock wool as a medium and the ph is normal for growing

lots of things here. first, stop nute'ing them, u have nute burn. also, your at 86F, at 30C, which is warm. try to get near 78F. you should be using MAYBE 25% of the advised directions ont he nute bottle. stop using bloom, thats for flowering stage. also, vent out your garden so you can bring your light down...it should be 18-22" away from the tops fo your plants and able to maintain 78F. also, buy a Hannah PH meter and test the ph of your water, as i believe that will be problem too. ph level should be 6.5 or right around there. between 6.3-6.8

also, you complained about no one responding...youre new here, you need to build up rep by learning, posting, and helping others. you can give people +reputation when they help you, which in turn will help you get better stnading in the community. hope this helps...hang in there..>RIU is fantastic for help man.

also, dont overwater them. wait until the soil dries out a little bit, and thenw ater them. word of wisdom: stil finger in soil to second knuckle. if tip of finger feels moist, no need to water, but water within the next 12 hours or so. if it is wet when you stick your finger in, dont water, and wait till first 1 1/2'' are dry.

the pic is blurry, but what your explaining on the stem sounds like it is damping out/stem rot, which means ya most likely gotta yank the sucker if it doesnt get better.

for some reason i can't sem to see the posts you guys are leaving me!! arrgghh!

fixed! got your posts thanks a lot man, ill get right on that now. and point taken about the building rep, im just panicking over losing my plants! they have grown rapidly since going into the tank but now i have an idea of what is going on! thanks snafu for your help, will let you know how the it turns out!

also let me know how to add to your rep as payment for your help! thanks dude

gotta post mroe and stuff. youll see a little scale in the top right corner of everyones post/replies when you becopme more recognizxed on RIU. keep posting, asking questions and interacting with the site sn dyou can leave rep.

its an nft tank im using with my nutrients mix,and the plants are in rockwool which always seems to be soaking. the guy in the shop told me to lleave the pump running all the time! is this incorrect?! ive turned it off for the time being anyway and will change the nutrients mix to what you suggested earlier. lastly, is it safe to have my lights so close to the tops of the plants when they emit so much heat?! thanks snafu

my bad dude, thought you were running soil, i failed to notice the rockwool in the pictures...post better pics man. m,ake sure the rockwool stays wet, its bad news if it dries out. thought u were on a soil grow. try to maintain a 5.8 ph level in your water tank.

you have to put your thermometer at the top of the plant between the plant and the light. monitor temp, make sure it stays near 78F. any warmer than that and its not beneficial. you can get away with 85, but the ebst is 78. best bet 5.8 ph, check ppm level of your water as well, all adjustments to ph levels to be made after nutes have been mixed. hydro is pretty unforgiving man, i would do soil if your a noob.

Totally agree. Soil is the place for noobs to learn as it is so much more forgiving! It's definately nute burn on ur plants and I suspect ph issues as well. Snafu called this one dead on the money! +rep to ya Snafu for nailling the problem! Also man totally stop using the bloom if ur vegging. It's not time for that yet. Follow Snafu's directions on nute dosage and ph and if the plants can still pull through they will. If they don't make it I advise doing some more research on growing and going with soil till you have a couple successful grows under ur belt. Experience is the best teacher and witnessing the changes these plants go through will better prepare you for dealing with hydro down the road. I think hydro is over-rated. You can grow plants just as dank from soil with a lil experience. Also I have a total of 1400 watts (all hps) going over 5 plants and my lamps only 20 inches from my canopy tops. Get ur lights closer and get ur temps down with better ventilation. You grow good pot with a good setup not good pot from a bad setup. Hope I've helped!

thanks for your posts guys, im broke so its hydro for now man haha! will definately take the advice given, cheers! ill keep you posted and get a few more pictures up soon.

Looks like root rot from too much water, what system are you using? If its drip, fine; if not, then something is wrong there. Don't know much about NFT but I don't think constant water can be good for them.

Also looks like Calcium deficiency, by the spots on the leaves. Buy some Cal-mag if you can. You need something with the micro-nutrients (calcium, iron, boron, etc..), which I believe grow and bloom do not have.

Also looks like a little heat and light stress. Burnt edges, leaf tips curling up, a little fading in color. Find a way to cool the place down then try to bring the light closer, seems a bit far.

Good Luck!!

ooooooookaaay! so 1 day after i found out i had multiple problems with my garden, i took the advice and dropped my nute dose drastically, moved my lights closer and vastly improved ventilation, well, as much as i could for it being in the closet but the temp seems to be ok now.ive adjusted my ph levels and just put the plants back in for flood about an hour ago! thing is, last night i stopped the flood system and thought the plants would do fine with the water contained in the roots. to my surprise, when i got back from college at 4pm, went straight in to have a look at the girls, i opened the door and two of my plants were completely wilted all the leaves had fallen andthe main stem was leaning! fuuuuck! i continued to do what snafu and the other guys suggested with moving my lights, checking then adjusting my ph to the correct level and increasing ventilation. ive put the plants in on the 25% strength nutrient solution with grow only!!! good news, within half an hour the plants have stood back up, they are not back to the way they were but seem to be coming back to life! will these plants be fine?! also, the other plant that did not wilt, the leaves are curling under all of a sudden and this has only happened since i put the plaants back in the tank! what does this mean?! any help would be brilliant guys!

probably stressed

here firsttimebuyer try this for a little read

http://www.amsterdammarijuanaseedbank.com/Growguides/troubleshootingsolutions/marijuana-plant-abuse.html