Please Help - Seedlings Leaves Dry Discolored/Browning

[Weston]

Hello,

I am growing two Northern Lights Autos under CFL.

They are 11 days from breaking soil and one of them has developed discoloration on its first set of fan leaves. It only seems to be affecting this plant and not the other.

Please see pics and ask if you need more info.

Any help or suggestions appreciated.

Thanks.

 

[Robert Celt]

Well I guess the first thing to do is get some more info from you

Soil/medium?
Watering? how much/often?
Are you using any nutes?

My first guess would be over watering but without knowing some more info, its hard to say

 

[Weston]

Well I guess the first thing to do is get some more info from you

Soil/medium?
Watering? how much/often?
Are you using any nutes?

My first guess would be over watering but without knowing some more info, its hard to say

Thanks for your reply,

- Multi-purpose non slow release compost
- I've been watering about 500ml at 6.5ph each plant when the first inch of soil feels dry - maybe every 2 days.
- About 3 days ago I noticed growth had slowed down a lot so I gave them 1mg of veg nutes in 1ltr of water which they shared.

 

[Weston]

Here is my grow log: First Grow - RQS Northern Lights Auto - 360W CFL

 

[Robert Celt]

Ok I went and had a look at you journal, and seeing the pot size helps a bit.

Unless your grow area has a very low humidity causing the soil to dry overly quick, I would still consider it to be caused by over watering. Plants that young don't require much water, maybe a couple ounces a day.

Because of the size of your pots, rather than feel for dry soil, let your pots dry out more until they feel quite light before watering. And make sure you have drain holes in the bottom of the pots, otherwise unused water will pool in the bottom of the pot causing root rot later on

 

[Emilya Green]

Thanks for your reply,

- Multi-purpose non slow release compost
- I've been watering about 500ml at 6.5ph each plant when the first inch of soil feels dry - maybe every 2 days.
- About 3 days ago I noticed growth had slowed down a lot so I gave them 1mg of veg nutes in 1ltr of water which they shared.

You are making the classic new grower of weeds mistake of watering too often. You are checking to see if the first inch feels dry, but what is critical and what you are not considering is, what is happening in the last inch of the container? Weeds need to dry out between waterings, and if you do not allow the lower roots to dry out and get oxygen once per wet/dry cycle, the roots drown and are unable to take up nutrients.

There is a thing called the water table in any container grow. This water table line must be allowed to drop down into that last inch of the container. You need to research the "lift method" to figure out when it is time to water, and then you must water to saturation or runoff, not some humanly determined amount. If you keep coming along every couple of days and adding water to the water table, it never drops below half way or so.

Let her dry out completely... so dry that you can not feel ANY water weight when you lift her up... and do this for 3 wet/dry cycles and your plants will recover... the dead stuff now showing will not come back, but at least the problem will stop progressing and your growth will restart.

 

[Weston]

So based on 10ltr pots and the age of the plants... how much and how often should I water? I don't see the lift method being viable for me as I can't determine weight difference by lifting the pots days apart.

 

[Emilya Green]

typically 3-4 days. You can always wait until you see a slight droop, but I prefer to hit them right before that point. I have found too that instead of lifting a large container, trying to give it a shove with one toe or one finger can give you a real good idea how heavy it is... a 10L container of dry soil does not weigh very much at all, and just moving it an inch can be as effective as lifting it. Once you get an idea how long your wet/dry cycle is, you can start using the same interval each time, and that would be 100% better than being a knuckle waterer.

A cheap moist/wet meter with probes that can go down to the bottom of that container will help too. With that probe you can easily "see" where the wet/dry line is and watch it go down over time.

 

[Weston]

Ok thank you.

Here is the other plant... how does it look?

 

[Emilya Green]

same thing starting? Those first fans are starting to crinkle... that is your first red flag. You get your second warning when the cotyledons start to yellow. Start in small containers, no more than a beer cup, and use the lift method... you will not have these problems any more.

 

[Weston]

Hmm.. I did germinate them straight in the 10ltr pots. The plant with the discoloration doesn't have yellowing of the cotyledons though... but I notice that the very tips of the second fan leaves are beginning to brown.

 

[Weston]

I had them out of the grow room earlier and made the drainage holes a little bigger. The plant that was most effected seemed dry - not much came out of the drain holes. The other plant that doesn't look so bad seemed to have a fair bit of water clumped at the bottom. As I punched the holes larger muddy water began to sludge out.

 

[Emilya Green]

Usually the cotyledons indicate early micronutrient problems, but starting out in the large containers gave you a time delay factor, but didnt do you any favors as far as root development is concerned, it just put a buffer into play.

Starting out in the 10L, your roots all headed toward the bottom, but there was still plenty of dry soil between the top and bottom, with active roots heading down there... so you have so far been able to absorb the nutrients needed so far in that vertical space. As the plant gets bigger though, her needs are increasing by the day and she needs a LOT of nitrogen. This has to come from the main roots... but of course as already discussed, they are underwater and have gone inactive. The macronutrient deficiency that resulted is why she started eating her lower leaves.

With very small plants in large containers, you can tease the plants into growing roots laterally though the pot by watering from the edges, never down the middle, and small amounts at a time. This is a very advanced technique and not recommended to new gardeners since it is so much easier to successively up pot and simply saturate the medium every time you water. Now, because of the large container, if you are going to have any chance of achieving a root ball like I manage to get, you are going to have to do some extraordinary things to get those roots going to their full potential. If you just learn to not water too often, you can save these plants, but to produce great plants, plants producing to their full genetic potential, you are now going to have to tease out a root ball by getting those roots to grow laterally throughout your container. All normal watering methods will have to be thrown out the window for a few weeks to do this, but it can be done.

 

[Weston]

Makes sense. When I first noticed signs of a problem I gave them nutrients. Because I was aware of them sucking nutrients out of old leaves. But I assumed they were deficient because the soil was barren... so the roots are drowning and so unable to absorb nutrients?

Oh man... I watered them earlier today as well =(

 

[Weston]

Really hard to diagnose on my own. I research say drooping and find that both under and over watering causes this symptom...

I looked up the discolouration and it can be nute burn or it could be nute deficiency... really hard to know what to do...

 

[Weston]

So... I should just leave them alone for now until the soil is completely dry?

 

[Emilya Green]

So... I should just leave them alone for now until the soil is completely dry?

absolutely... best thing you could do

 

[Weston]

And then begin to lightly water around the edges of the pots?

 

[Weston]

I was reading all the time about the most common beginner mistake is over watering or just generally doing too much... And I still made the mistake of doing that anyway xD

 

[Emilya Green]

I was reading all the time about the most common beginner mistake is over watering or just generally doing too much... And I still made the mistake of doing that anyway xD

Don't feel bad, that is why it is so common... the concept of watering too often doesn't occur to a lot of folks. The second most common mistake is to over nute. Plants in veg in good soil don't "need" nutes. Healthy plants, getting lots of light and air, can use nutrients as supplements to increase the normal growth... but it is a mistake to try to replace good light and air with nutrients that are unable to be used.