Right I have x2 plants one seems completely fine, other is acting strange with its leaves canoing/cupping up: see photo: View attachment 137638 Both are in grow tent, with 400w MH light, extractor fan, fan blowing on plants lightly. Temp hover around the 75 mark. Both are white widows. Lights have been raised up to 10" currently. Repotted both yesterday slightly early then planned, watered both with a litre of water. Other plant looks like this: View attachment 137639
Ouch, that one is looking pretty bad now. You said you haven't given them any nutrients yet? I don't remember. A couple things to check might be the PH and PPM of your tap water if that's what you are giving them. Although, one would think that if it was a problem with the water, both plants would react the same. Hopefully someone else can throw in some more knowledgeable advice than me.
Nope not giving either of them any nutrients yet. When repotted both yesterday, the problem plant did a massive stem under the soil roughly 2.5" high. Both have been watered after repotted but are't due for more water till at least wed night or thursday morning.
Maybe you should try feeding nutrients when you water them on Thursday. At this point your conditions are right so it's sort of a guessing game as to what is going on there.
Ok just pulled up the lights to 20", I'll see how they go today. Temps are just under 30c, which is the best I can get at the moment.
Starting to think my temps are too high, am pushing over 30c sometimes. I've moved my fan around slightly and I can maintain just under 30c now. Also moved my light up to 20" above plants this morning, to see if that makes a difference. There is lots of new growth on the taller problem plant, but loads of the leaves are still canoed upwards. What sort of nutrients would you recommend? Bearing in mind both plants are only 3.5 weeks from seedlings.
You definitely have heat issues if you are reaching 30C, you want your maximum temperature to be at or under 80F which would be 26.5C. If the light is open air not air cooled 10 inches with a 400 watt metal halide is far too close even for older plants. I have a small 150w hps and the leaves will start to cup at 10 inches, when I put it up to 12 inches they are fine. But that is at over 2 months in veg with 2 oscillating fans so they would be less sensitive then a small seedling and the room doesn't get over 80F. If they start to recover at 20 inches slowly lower the light like an inch at a time as they get bigger so you don't shock them, if the leaves start to cup or you see other signs of heat stress back the light off again until you find just the right height. There are a wide variety of base nutrients that will all work similarly and have similar formulations but it would be best to hold off feeding them until they show signs of needing it or you could end up with nutrient burn. Some common ones are like Advanced nutrients jungle juice 2 and 3 part systems, General hydroponics 3 part, General organics 3 part, etc....
I use Advanced Nutrients PH Perfect Sensi grow and Sensi Bloom, along with some other supplemental nutrients. They are great but sort of on the pricey side. Check out your local hydroponics store and talk to someone about what is best for you and your budget.
Cheers have raised my light and given slight bit more water today, the problem plant has responded well and all its new leaves on top have opened up. My other plant has perked up too, since the lights have moved up.
You can start with a half dose right now, or as soon as you buy them. Honestly, if you can, Advanced Nutrients are the best because they are made specifically for cannabis. Check out their website: www.advancednutrients.com General Hydroponics are also decent, but they are not made specifically for cannabis, so you have to be more careful not to over feed.
Yep cheers for your advice, moved lights about 20" away. Still can't close tent as I have a crappy extractor fan, but am gonna get sort asap.