Back Growing, Potential CalMag Issue?

[LucasAM]

Hi Guys,
Its my first grow in a number of years.

I am using pre buffered coco and added perlite.
Using Canna Coco A+B nutes + canna additives.
100w LED running at 50% brightness, hanging around 19Inches.
Currently have around 4 nodes produced and only recently switched the LED from 25% to 50%

About 3 days back I noticed some yellowing come through in the leaves.
I checked my nutes and realise I had been under feeding.

I've now ramped up the doses:

PH 6 - 6.1
EC 1100
5ml Canna A+B diluted in 0.66 gallons

Not much has changed in the 3 days, any ideas?
Cheers, Lucas

 

[ArtfulCodger]

Interveinal yellowing like that is the start of what's called "tips and stripes," and it happens when the uptake of certain nutrients can't keep up with the light intensity. You can try to fix it with more nutes, but the easiest thing to do is turn down (or move up) your light.

 

[LoveGrowingIt]

It looks like it could use some Mg, so a tablespoon of Epsom salt per gallon of water would help. The plant(s) are also ready to be transplanted into a larger pot.

 

[Imzzaudae]

A 100w input led will have a light output in the 300w range.
Keep the light 24" above your canopy so the light spreads out 24"x24" at canopy.
I noted a few light stress blisters on your leaf surfaces. Light is to hot.
A small plant like this will require minimum feeding. Do not over feed.
Water well when feeding once a week. A little water mid week will not hurt if needed. If it's not dry don't water.

Fungus Gnats on sticky paper tell me your over watering. If you only need to water once a week then feed one week.
Just water the next and your plant will be quite happy. It will grow bigger and require more water and food before long.

A plant this age should not have calcium or magnesium issues. I'd say leaf discoloration is more likely light stress
and over watering related.

 

[LoveGrowingIt]

Fungus Gnats on sticky paper tell me your over watering. If you only need to water once a week then feed one week.

They'll keep showing up when watering because the eggs hatch in response to the moisture. I understand they like soils containing wood chips, like Fox Farm Happy Frog. I'm not sure it's even possible to avoid them if using soil that they like. I suspect it depends on the local environment. We live in a woody area, so there are plenty of local gnats willing to make a home in my tents.

Usually, they show up within a day of watering. I spray the top of the soil with a peroxide solution when I see them. It pretty much kills them on contact, but it's darn near impossible to spray them before they've laid more eggs. (I also use alcohol sometimes or commercial products, like AgroMagen GrowSafe.) I also sprinkle diatomaceous earth on top of the soil when the surface is dry. That kills them as they crawl across the soil. It waters in quickly so it needs to be reapplied. I drilled a bunch of holes in the lid of a jar to use like a saltshaker to apply the DE. I also use those yellow sticky things. I still have fungus gnats.

 

[LoveGrowingIt]

A plant this age should not have calcium or magnesium issues. I'd say leaf discoloration is more likely light stress

Yep. It could be light stress. I often wonder whether what we describe as 'light stress' occurs because the plant doesn't have what it needs to handle the amount of light it is receiving. Magnesium is especially important because it is the central atom in chlorophyll—the green stuff. Arguably, a plant needs the right amount of everything, all the growth factors, for it to grow with vitality. So, a question might arise regarding whether the plant is getting too much of one thing or not enough of another thing. Reducing the light intensity certainly is a tried-and-true solution, but it might not be the only solution or even the best solution. I suppose it's all about finding the right balance of all the things a plant needs.

 

[LucasAM]

Interveinal yellowing like that is the start of what's called "tips and stripes," and it happens when the uptake of certain nutrients can't keep up with the light intensity. You can try to fix it with more nutes, but the easiest thing to do is turn down (or move up) your light.

Unreal! Thank you, certainly sounds like it.
I'll dim the light back to 25% and monitor.
Thanks again.

 

[LucasAM]

It looks like it could use some Mg, so a tablespoon of Epsom salt per gallon of water would help. The plant(s) are also ready to be transplanted into a larger pot.

Fantastic! Thank you! will monitor.
Yes, will be repotting in the morning! Roots definitely growing out the bottom now.

 

[LucasAM]

A 100w input led will have a light output in the 300w range.
Keep the light 24" above your canopy so the light spreads out 24"x24" at canopy.
I noted a few light stress blisters on your leaf surfaces. Light is to hot.
A small plant like this will require minimum feeding. Do not over feed.
Water well when feeding once a week. A little water mid week will not hurt if needed. If it's not dry don't water.

Fungus Gnats on sticky paper tell me your over watering. If you only need to water once a week then feed one week.
Just water the next and your plant will be quite happy. It will grow bigger and require more water and food before long.

A plant this age should not have calcium or magnesium issues. I'd say leaf discoloration is more likely light stress
and over watering related.

Great! Thank you.
My last grow was in 2010, LED technology wasn't so advanced, impressive stuff these days.

I spent allot of time absorbing information on cocoforcannabis. I felt his watering/fertigation methods were alitte excessive, (twice a day) even with 'oxygen at roots' arguments.
Will dial back feedings.

Thank's again :)

 

[Gmix]

They'll keep showing up when watering because the eggs hatch in response to the moisture. I understand they like soils containing wood chips, like Fox Farm Happy Frog. I'm not sure it's even possible to avoid them if using soil that they like. I suspect it depends on the local environment. We live in a woody area, so there are plenty of local gnats willing to make a home in my tents.

Usually, they show up within a day of watering. I spray the top of the soil with a peroxide solution when I see them. It pretty much kills them on contact, but it's darn near impossible to spray them before they've laid more eggs. (I also use alcohol sometimes or commercial products, like AgroMagen GrowSafe.) I also sprinkle diatomaceous earth on top of the soil when the surface is dry. That kills them as they crawl across the soil. It waters in quickly so it needs to be reapplied. I drilled a bunch of holes in the lid of a jar to use like a saltshaker to apply the DE. I also use those yellow sticky things. I still have fungus gnats.

They love organic food all that rotten matter is heaven for them.

I use guano and it’s like a magnet for them.

It is possible to not have them but very very easy to have them especially in organic soil

The best thing to do is get some nematodes they take care of them no problem and if any new ones enter there gone as they can last upto 4 weeks usually even a serve infestation can be dealt with by just one packet of them.

I’ve tried loads of stuff from de to tanlin , mosquito dunks and everything in between and highly recommend them.
Btw to much de will raise your ph.

I’d highly suggest you do get some.

Fungus Fly Killer Nematodes

What are Fungus Flies? The Fungus Fly, also known as the Sciarid Fly, can cause severe damage to plants. These tiny flies will lay eggs in compost or soil, from which larvae will develop. The larvae feed on young plants and seedlings at propagation. Fungus Fly are also a common pest in...

www.dragonfli.co.uk

 

[Gmix]

I say it’s possible to get rid that I’ll stick by however it’s not always possible to stop them invading depending on where your grow room is. I used to get them no matter what in one of my rooms.
It’s bro science that you get them because your overwatering and such when folks say let your pots dry out to get rid. They love nothing more than a dried out broken root your plants will die before they do. I did a load of research into them and there lifestyle hence saying what I have

 

[LucasAM]

*Update*

Plant repotted into felt pot.
Still a coco/perlite mix, topped off the surface with straight coco mix to fill out remaining pot.
Raised light 24" above and dimmed back to 25%.
Have left nutes as previous post.

Plant looking greener/healthier overall.
The two largest leave tips have started cracking, so id assume majority of the orgional problem was light related.
Lets see how the next week plays out.

Thank you all.

 

[LucasAM]

Also, that bottom leaf curling inwards looks as a overwatering issue,
Have cut back on waterings.

 

[Sunasun]

*Update*

Plant repotted into felt pot.
Still a coco/perlite mix, topped off the surface with straight coco mix to fill out remaining pot.
Raised light 24" above and dimmed back to 25%.
Have left nutes as previous post.

Plant looking greener/healthier overall.
The two largest leave tips have started cracking, so id assume majority of the orgional problem was light related.
Lets see how the next week plays out.

Thank you all.

Why aren't you watering fully? You need to water the whole pot, not just some weird moat around the plant. Your medium is hydrophobic now and will repel water and severely hamper your plant's root system development.