Day 14, seedlings are slow-growing and cotyledons are looking unhappy: Help?

[BT42021]

Hi all,

This is my first post and my first grow.

I have 4 seedlings of Special Queen #1. Seeds were germinated by paper towel method. Due to a lack of light, some strecthing was occuring during first week of growth. A few days ago I transplanted the seedlings into larger pots, burying part of the stems. I have now moved these plants into a bookshelf, and I'm lighting them with LEDs, 6-8 inches above the plants (on a 16/8 cycle). These LEDs are a 10m strip, bought online - I'm not sure of their exact output. They do get slightly warm.

I was expecting more growth than this by day 14 - only one of the plants is just beginning to develop her second set of true leaves.

Two of them are looking OK, but the cotyledons are beginning to yellow (I understand this happens naturally, but not this early).

One of the seedligs is looking very unhappy, with yellow, curled up cotelydons. The 1st true leaves have barely been growing and the plant looks very unhappy.

I have been very cautious of over-watering - Is this a sign of under-watering? All plants have been treated the same - watered at the base of the stem with 3ml water every second day (when in small nursery pots), until transplanataion into these larger pots. I used shop-bought compost (for seedlings) with no additives. The larger pots have been watered by sitting them in a tray of water, 1" deep for 30-40 seconds. These larger pots mean I can stick a finger an inch or two down to feel for moisture - the soil felt dry but after watering it felt slightly moist, but was not yet sticky or by any means wet - it did, however, definetly feel warm.

Might it be that the lights are too close? I have kept the area damp with wet papar towels to ensure high humidity (and reduce the teperature slightly). I don't have any pH or temperature measurements but where I live we have good quality, neutral pH tap water. The teperature in the grow space is possibly too warm, it feels around 30°C. The lights feel warm to the touch, but not hot.

Am I right in thinking I have too much heat and too little water?

I will update this thread with photos and information as the plants grow. Any suggestions welcome! I'm trying to keep cost as low as possible.

Many thanks,
B.

 

[013]

Hey BT!

Welcome to 420! Looks like they are planted in coco, can you find the bags the substrate came in and shoot a pic of the labels and post here? Coco is not the same as soil, it’s a totally different animal and needs unique treatment. Coco is inert meaning there are zero nutrients in coco to sustain a plant so it must be bottle fed low dose nutrients.

But before we can advise you further we need to know exactly what the seedlings are planted in.

The cotys are yellowing out for a reason - they are a backup source of energy for the seedlings and your seedlings are pulling energy from the cotys. You really need a hygrometer to tell you the temp and rh of your grow space... this is critical. For indoors it’s not enough to monitor the temp & rh - you must be able to control them. 28 is about the max for indoors. You can use a large pan of water with a fan pointed at the surface to increase rh. A gentle fan moving air near the seedlings will help strengthen the stems

Suspect the lighting is too weak, can you dig up more info on their output and post it here?

My 2 cents and more folks will jump in soon.

 

[Nunyabiz]

Looks like straight coco.
IF it is water everyday with 1/4 strength nutrients that is made for coco.
And water enough to wet the pot.

You're going to need a lot more light if that is your only light source.

If those are autoflower then you can just yank them up they're toast.
If photo-period you can save them

 

[BT42021]

So great to get such fast replies!

Growing medium:

Lighting:

• 4W
• 600 SMD 2835 LEDs
• Daylight White 6000K
• 1800lm, Dimmable

I'm using the same lights as I did when I experianced some seedling stretch, they were about 2-3 foot from the seedlings at this time, and were in a large cupboard. The seedling strectch here was only moderate - I dont have any pics but the stems were still nice and green, and were able to supprt themselves easily. By the time the first true leves were developing, stem length was approx. 2.5".

 

[BT42021]

Looks like straight coco.
IF it is water everyday with 1/4 strength nutrients that is made for coco.
And water enough to wet the pot.

You're going to need a lot more light if that is your only light source.

If those are autoflower then you can just yank them up they're toast.
If photo-period you can save them

They are photoperiod!

 

[Nunyabiz]

When you transplant and you use that same soil i would add about 30% by volume of aeration such as pumice, Rice Hulls, and or Pre-charged Biochar.
Then use a wetting agent like Yucca Extract and just water like normal, keep it moist not saturated or dry.

 

[Emilya Green]

Hi @BT42021 and welcome to the forum!
You have your seedlings in a very light soilless sphagnum moss medium made for cuttings and seedlings. There is almost nothing in there to provide for the plant's nutrition. Not finding what it needs in that soilless mix, your seedlings are sacrificing the stored up nutrients in the cotyledons, but this won't last long at all before your plants are in big trouble. You need to start feeding immediately, or put them in a good SOIL. Also, your bottom watering technique is less than optimum... it is a hack, designed for people who don't have the energy or time to actually water from the top. Watering from the top does a lot of great things for your roots, and you really should look into doing this properly.

 

[BT42021]

Hi @BT42021 and welcome to the forum!
You have your seedlings in a very light soilless sphagnum moss medium made for cuttings and seedlings. There is almost nothing in there to provide for the plant's nutrition. Not finding what it needs in that soilless mix, your seedlings are sacrificing the stored up nutrients in the cotyledons, but this won't last long at all before your plants are in big trouble. You need to start feeding immediately, or put them in a good SOIL. Also, your bottom watering technique is less than optimum... it is a hack, designed for people who don't have the energy or time to actually water from the top. Watering from the top does a lot of great things for your roots, and you really should look into doing this properly.

I will get feeding ASAP. I thought watering from the bottom was meant to reduce the chance of drowing the roots and pushing air out the mix, but I'll look into this.

Can you suggest a good NPK ratio, and concentrations to use on these young plants? I understand a lot of people don't fertilise until they start vegging. I think i have some miracle-grow plant food with an NPK of 7: 3: 5. Would this be ok? Do you suggest getting them straight onto a full veg dose, or slowly introduce the plants to the fertiliser?

Thank you!!

 

[Emilya Green]

I will get feeding ASAP. I thought watering from the bottom was meant to reduce the chance of drowing the roots and pushing air out the mix, but I'll look into this.

Can you suggest a good NPK ratio, and concentrations to use on these young plants? I understand a lot of people don't fertilise until they start vegging. I think i have some miracle-grow plant food with an NPK of 75. Would this be ok? Do you suggest getting them straight onto a full veg dose, or slowly introduce the plants to the fertiliser?

Thank you!!

A lot of very timid people in the online world choose not to use fertilizer until week 4 or 5 of veg, when their soil runs out of nutrients. This in my humble opinion is silly. Why go to the expense of buying expensive nutrients if you are not going to use them for their intended purpose... to make your plants bigger than they would have been without them?

I strongly suggest that you find a nutrient that is specifically made to grow cannabis. Miracle Grow is not formulated for this task and it will get you in trouble. If you are forced to use this for now, go very lightly... you should be able to find a suggested dosage to give to young seedlings. I also suggest that you look for some real soil, for your next uppotting... this should have been what they are sitting in now. It is not a disaster, because you can feed your way out of this.

For ease and simplicity and no guesswork required, please let me suggest one of our sponsors to be your nutrient provider. I am having very good luck and am getting consistently excellent results by using @GeoFlora Nutrients. Simply top dress once every two weeks and water it in and use plain water inbetween. It doesn't get easier than Geoflora.

Lastly, the watering. It is not a goal to drive air out of the soil, because plants need oxygen at the roots almost as much as they need water. Bottom watering greatly increases the chance of drowning the roots, it doesn't decrease it. Please take some time to read my best known writing on this matter, how to properly water a potted plant. The link is in my signature. This concept of establishing a strong wet/dry cycle has been proven over the last 10 years to be a superior way of watering these weeds. Weeds have two root systems, and your bottom up method ignores the use and function of the top spreader roots.

 

[Nunyabiz]

That soil claims to have the nutrients needed for seedlings.
So most likely you just need to water properly and have decent light.
I would put some kind of wetting agent in your water such as Yucca Extract or Aloe Vera and make sure all the soil is moistened well, the wetting agent has the added benefit of allowing the plants roots to utilize the nutrients in the soil more efficiently.

Then get some better lighting.

 

[BT42021]

Hi all,
Just to give an update. Its now been 4 weeks. Trying to keep costs low, I fertilised the soil with some tomato food I found in a cupboard (NPK 4: 3: 8) and it helped out the plants a lot. I didn't do much to them for a few days after posting - the most sad looking plant unfortunately died, but the other three did not meet the same fate. I have now watered three times with this fertiliser, at the concentrations suggested for tomato growing. One of the plants is slightly smaller than the other two, but all of them now look happy. I have seen a lot of growth since using fertiliser. The lighting used has proven successful, but it's about time to repot, move the plants into a larger grow space and get a new light. I'm also going to repot into some better quality soil. I plan to repot into 10L pots, and begin the flowering stage in about two weeks time.

 

[Nunyabiz]

If you're going to feed with salt based nutrients you would be better off transplanting into a 4 gallon fabric pot full of coco with about 20% pumice and a touch of biochar.
Then water every single day with 1/4 strength nutrients pH to 5.8.

If you do soil the best by far is buy or make a Clackamas Coots soil recipe and fill a 15+ gallon fabric pot.
And just water with plain water and a little Yucca extract.
Also water about everyday but not to runoff, use between 5-10% by volume of pot.
So a 20 gal pot use 1 gal of water per day and once in awhile maybe give a little more especially in late flower.