What am i doing wrong??!!

YorkshireNewbie · Jul 16, 2025

Hi guys.
I'm Baz.

I started growing three white widows about 6 weeks ago, and I've had a near constant battle with fungus gnats and canoeing leaves, but I dont know what I'm doing wrong and its really demoralising.

Ive got fans, a humidifer, a decent enough tent, and the plants are growing fine, but every day when I get home from work the leaves are canoed and its getting me down.

Ive spent a lot of money on the best equipment i can afford, which isn't much compared to most of you, but 6 weeks ago I was just a regular Joe, with no growing experience, no equipment and no idea. Ive done the best I could to get a proper set up, but what do you guys think?
Ive got to where I am through you guys helping.
Suffice to say, I lack the knowledge or experience to diagnose this issue, or treat it, so once again I turn to you guys.

As you can see from the photos, its not a huge tent, but I can't see anything wrong with it.
The fungus gnats are a pain, but they're not a crisis.
These canoeing leaves are a crisis.

How the hell do I sort it out???

Ive ordered a 4 inch booster duct fan so I can remove the 6 inch desk fan which ive got tied into the inlet vent. I think the 6 inch desk fan is too powerful and is contributing to the leaf curl.

Ive ordered a fan speed adjuster to turn the internal oscillating fan speed down, for the same reason as above.

I'm also going to or

Ive ordered another viparspectra light so ill have 300W on the canopy, and better dispersed light. Each plant will then have about 100W/1000w of LED light to itself.
der some Co² bags and maybe some ph up & down because thus far I've been using tap water, de-chlorinated if I've remembered to leave a bucket overnight full of tap water, otherwise they're fed with regular British tap water.

Ive got some plant magic coco A+B
Ive also got some calmag.
Ive got some plant magic coco grow and plant magic coco bloom, and after a wobbly start ive settled into a decent watering regiment of one soak until there's a bit of run off, and I'm doing this every third day.

On the face of it, the plants SHOULD be fine, but they're not, and I just can't figure out why.
I'm also noticing leaves suddenly having bits cut out, as if a caterpillar has nibbled at them, and little holes which look like someone's held a magnifying glass on one spot for too long under bright lights.

Ive tried to take photos which show the problems I'm explaining, and I've taken a photo of my tent set up to see if anyone can maybe see something I could do better.

What can I do guys?
Ive juat flipped to 12/12, just yesterday, and these photos are after their first 12 hour night cycle.

It's just killing me now.
It also looks like somethings eating parts of my leaves but I've checked foe bugs and can't see any.

Can anyone diagnose this problem?
Ive tried turning the inlet fan off, that didn't help.
Ive tried tur ingredients the internal fan off. That didn't work.
Ive tried having no fans on, and that didn't help.

What the hell is it?!

LoveGrowingIt · Jul 16, 2025

YorkshireNewbie said:
I started growing three white widows about 6 weeks ago, and I've had a near constant battle with fungus gnats and canoeing leaves, but I dont know what I'm doing wrong and its really demoralizing.

Canoeing leaves usually means the light is too intense. You could try reducing the power or increasing the distance from the lights to the plants.

Fungus gnats thrive in wet soil, so the best way to control them is to let the top inch or so of the soil dry. That's where the fungus gnat larvae live, but they need moisture. There are other ways to control them, but dry backs are best, and they're good for the plants, too.

YorkshireNewbie · Jul 16, 2025

LoveGrowingIt said:
Canoeing leaves usually means the light is too intense. You could try reducing the power or increasing the distance from the lights to the plants.

Fungus gnats thrive in wet soil, so the best way to control them is to let the top inch or so of the soil dry. That's where the fungus gnat larvae live, but they need moisture. There are other ways to control them, but dry backs are best, and they're good for the plants, too.

Ive done both mate. I lifted the light by 12 inches and turned it down to 50% and the canoeing seems to be even worse today

YorkshireNewbie · Jul 16, 2025

YorkshireNewbie said:
Ive done both mate. I lifted the light by 12 inches and turned it down to 50% and the canoeing seems to be even worse today

Probably worth mentioning I'm in northern England where the humidity is about 70%, and the leaves are curling all the way up the plants.

JIMKSI64 · Jul 16, 2025

This looks like a lot of things, and that's a problem. You have to go down and eliminate the list one by one.
First is lights. It sounds like you have only one light right now. Prolly not it but if you have a way to measure your ppfd and DLI do so to eliminate any issues.
Chemical ferts almost always benefit from flushing if the medium is a type where salts can build up.
Heat stress. Running in the 90's?
Low humidity. And consequently high VDP.
One other thing. If the canoeing does not stop at night rest you have eliminated a whole bunch on the list.
What are the temp and humidity.

LoveGrowingIt · Jul 16, 2025

YorkshireNewbie said:
I'm in northern England where the humidity is about 70%

If that high humidity is inside the tent, then it's too high. A dehumidifier might be in your future if you don't already have one. It needs to be below 60% and near 50% or lower for flowering.

Gnats have a 17-day life cycle, so letting the soil dry back once isn't likely to eradicate them. A common method is to use baking soda by sprinkling it lightly on the soil and then moistening it. It has a high pH, though, so using it isn't without a potential downside. There are commercial products that work well, too. I've not used any, so I can't make any recommendations, and I have no idea what might be available where you are. In my experience, however, I haven't seen a gnat since I learned about letting the soil dry. How often do you water?

YorkshireNewbie said:
Ive juat flipped to 12/12, just yesterday

Flipping to flowering lighting complicates diagnosis and remedies. It's good practice to make sure the plants are healthy before doing so.

doober · Jul 16, 2025

your plants look great for your first grow so don't be down about that at all. it could be lighting, it could be heat or humidity as well what are your environmental, temperature and relative humidity in the growing area?

mancorn · Jul 16, 2025

The cupping doesn’t looks all that bad. Agree with the other comments on lighting & temp. If these are in check, I’d guess over fertilization with the leaf tips starting to claw and the twisted leaves. If your nutrients solution is too strong, minerals will clog the roots system, making them unable to uptake and transport water, which can then causes the canoeing.

Oldchucky · Jul 16, 2025

In my opinion, CO2 is an advanced technique! Leave it to the experts! Spend your money elsewhere till you reach that point! Agree with above! They don’t look too bad! Good luck!

YorkshireNewbie · Jul 16, 2025

LoveGrowingIt said:
If that high humidity is inside the tent, then it's too high. A dehumidifier might be in your future if you don't already have one. It needs to be below 60% and near 50% or lower for flowering.

Gnats have a 17-day life cycle, so letting the soil dry back once isn't likely to eradicate them. A common method is to use baking soda by sprinkling it lightly on the soil and then moistening it. It has a high pH, though, so using it isn't without a potential downside. There are commercial products that work well, too. I've not used any, so I can't make any recommendations, and I have no idea what might be available where you are. In my experience, however, I haven't seen a gnat since I learned about letting the soil dry. How often do you water?

Flipping to flowering lighting complicates diagnosis and remedies. It's good practice to make sure the plants are healthy before doing so.

They've only had 2 nights of 12 hours darkness, so am I going to be alright turning my timer back to 18/6?

LoveGrowingIt · Jul 16, 2025

YorkshireNewbie said:
Iv'e done both mate. I lifted the light by 12 inches and turned it down to 50% and the canoeing seems to be even worse today

Another somewhat rare cause of canoeing is high humidity or low vapor pressure deficit (VPD). It has to do with the stomata on the underside of the leaves. Stomata are pores through which the plant transpires moisture. When the humidity is high, stomata open excessively. That increases the surface area of the underside of the leaves, which in turn curls the leaves upward. That would explain why leaves lower on the plant are canoeing.

The basic idea is the plant needs to transpire but can't do so as much as it needs. That's due to the high moisture content of the surrounding atmosphere. So, it opens its stomata wider. The solution is to lower the humidity or increase the VPD.

VPD provides a measure of the plant's ability to transpire. Most environment controllers calculate VPD, which is helpful, but there are charts for it, as well.

LoveGrowingIt · Jul 16, 2025

YorkshireNewbie said:
They've only had 2 nights of 12 hours darkness, so am I going to be alright turning my timer back to 18/6?

I think so. I've had power outages that lasted more than a day, and the plants did okay. I've not encountered what you're contemplating, however. My thinking is they evolved to survive cloudy days, so this might not be much different for them. Cannabis is a very resilient plant.

YorkshireNewbie · Jul 16, 2025

mancorn said:
The cupping doesn’t looks all that bad. Agree with the other comments on lighting & temp. If these are in check, I’d guess over fertilization with the leaf tips starting to claw and the twisted leaves. If your nutrients solution is too strong, minerals will clog the roots system, making them unable to uptake and transport water, which can then causes the canoeing.

On the nutrients bottles it says to give them 2-4ml per litre, and I've been giving them 4ml, every watering for the past 2 weeks, which is obviously the top of the recommended dose.
They've been getting 4ml of calmag every watering too, and I've also been giving them coco grow A+B too.

I'm using a mix of perlite, coco and compost, for what that information is worth, and I've been watering them until some I got some run off.

YorkshireNewbie · Jul 16, 2025

LoveGrowingIt said:
Another somewhat rare cause of canoeing is high humidity or low vapor pressure deficit (VPD). It has to do with the stomata on the underside of the leaves. Stomata are pores through which the plant transpires moisture. When the humidity is high, stomata open excessively. That increases the surface area of the underside of the leaves, which in turn curls the leaves upward. That would explain why leaves lower on the plant are canoeing.

The basic idea is the plant needs to transpire but can't do so as much as it needs. That's due to the high moisture content of the surrounding atmosphere. So, it opens its stomata wider. The solution is to lower the humidity or increase the VPD.

VPD provides a measure of the plant's ability to transpire. Most environment controllers calculate VPD, which is helpful, but there are charts for it, as well.

Thats awesome information, mate!

I really appreciate this.

YorkshireNewbie · Jul 16, 2025

Oldchucky said:
In my opinion, CO2 is an advanced technique! Leave it to the experts! Spend your money elsewhere till you reach that point! Agree with above! They don’t look too bad! Good luck!

Is there anything you'd advise to purchase?

Ive ordered a fan speed changer so i can turn the fan speed down (incidentally I just raised the oscillating fan as high as it'll go, so its not blowing directly onto the plant now, and within an hour the curling has eased up significantly)
I think i need a hygrometer and thermometer, but is there anything else you'd suggest?

LoveGrowingIt · Jul 16, 2025

YorkshireNewbie said:
I think i need a hygrometer and thermometer, but is there anything else you'd suggest?

The hygrometer and thermometer are helpful, but they're not as helpful as an environmental controller. Trying to control it manually is difficult. Even weather changes can change what's happening inside the tent. It's so much easier for the grower and better for the plants to have that controlled by a computer that's made for the purpose. Many of them have phone apps, so you can monitor the status and make changes remotely.

Oldchucky · Jul 16, 2025

YorkshireNewbie said:
Is there anything you'd advise to purchase?

Ive ordered a fan speed changer so i can turn the fan speed down (incidentally I just raised the oscillating fan as high as it'll go, so its not blowing directly onto the plant now, and within an hour the curling has eased up significantly)
I think i need a hygrometer and thermometer, but is there anything else you'd suggest?

These guys will point you in the right direction on what to spend your money on instead of CO2!

JIMKSI64 · Jul 16, 2025

YorkshireNewbie said:
On the nutrients bottles it says to give them 2-4ml per litre, and I've been giving them 4ml, every watering for the past 2 weeks, which is obviously the top of the recommended dose.
They've been getting 4ml of calmag every watering too, and I've also been giving them coco grow A+B too.

I'm using a mix of perlite, coco and compost, for what that information is worth, and I've been watering them until some I got some run off.

Ok little chime in.
Coco and perlite good
Coco good.
Coco and compost and then a/b chemical ferts are cross purpose. Compost is for an organic grow. Coco has to stay wet and the fact that you have gnants in coco says they are wet but the compost remains water. Most coco is fertigated at least daily
The nutrients and the schedule.
Pouring max nutes is for dialed in grows with a steady vdp and appropriate lighting and temps. If you are flying without a controller system this will be very difficult to achieve.

cal mag. Read the nutrient bottles. Like the spaghetti sauce commercial " it's in there " I see no need for cal-mag with those nutes.

Just my input but you are feeding this like a soil grow and not coco.
This grow is not shot. This is recoverable. There are a few guys here on the farm who do coco and soil and good bless them but I have no real recommendations for this.
The medium comment was the cue. Once again we all or maybe just a few need to work on a help ticket format to get grower info before we suggest a million things

mancorn · Jul 16, 2025

YorkshireNewbie said:
On the nutrients bottles it says to give them 2-4ml per litre, and I've been giving them 4ml, every watering for the past 2 weeks, which is obviously the top of the recommended dose.
They've been getting 4ml of calmag every watering too, and I've also been giving them coco grow A+B too.

I'm using a mix of perlite, coco and compost, for what that information is worth, and I've been watering them until some I got some run off.

Are you using plant magic coco A+B in addition to another nutrient? You say 4ml of ? every watering, 4 ml of calmag, and also coco grow A+B. Am I understanding this right?

mancorn · Jul 16, 2025

YorkshireNewbie said:
I'm using a mix of perlite, coco and compost, for what that information is worth, and I've been watering them until some I got some run off.

100% agree with Jim, your “soil” is a strange setup. Especially as “compost” could be almost anything (and normally mixed in at about 20% to forest humus and/or peat based soils).

What am i doing wrong??!!

What am i doing wrong??!!

YorkshireNewbie

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