Seedlings with yellow tips - Please advise! Photos included

[Crow]

Here are 5 Northern Lights in the beginning of their 3rd week from seeds.

• Planted in 3" COW pots
• Soil is the basic potting soil from "Coast of Maine" - their Bar Harbor Blend
• Under 400 watt MH set about 18" away
• Average temps - mid - 70°s F with little fan blowing full time
• Lights on 18 hours


• Expected to transplant to larger pots this weekend (3 weeks) and move to dedicated grow space under 600 watt LEDs. At that time I will also be switching to a more nutrient rich organic soil - the COAST of MAINE - Stonington Blend

Started noticing this yellowing of the under leaves a few days ago.

Potential causes?

1) Not enough watering? I have only given these guys a little drink every day. Just wetting the top - no saturation whatsoever. The 2 sponges are just there to add humidity and when they are dried out I have added water to the plants.

YESTERDAY - I started adding a full watering - not saturated but a good soak that should hold for a few days.

2) Too close to the light? Was at 12" until I noticed the yellowing - now moved to 18". There was NEVER any overheating. Temps have been constant in the mid- 70s°F by adjusting the proximity of the fan.

3) COW POTS adding to many nutrients?


Solutions?

1) Already started by adding more water and moving lights?

2) Should I cut off the yellow leaves?

3) Do you agree - I should transplant to bigger pots by the end of the week?

Thanks for any and all suggestions.

I've read the diagnostics, so very well presented by Nebula, but there are sooo many reasons for yellowing leaves that I thought best to ask before I jump off the deep end with fixes.

Crow

[Qwertywill]

I know seedling/early veg they are sensitive to nutrients..

1) Already started by adding more water and moving lights? More light isnt a bad thing! 400w should be sufficiant. You will definitly need to see what the distance from cannopy to lights should be for this stage.

2) Should I cut off the yellow leaves? I would leave them to use as much light as they can, even if not much. When they brown and die, they will fall off.

3) Do you agree - I should transplant to bigger pots by the end of the week? Absolutly, they could be root bound. A larger pot will give them more breathing room!


Keep your watering as is, water but dont overwater.

I am still a noob, but more experienced growers will respond!

[Crow]

Could be root bound already? I'll be impressed if that's the case. Will need to take photos
Thanks for the help.

Crow

[Qwertywill]

I wouldnt doubt it. Keep in mind it needs to grow an extensive root system to feed and water itself. Not only search for nutrients....

Here is a video of a seed sprouting. Its not an mj plant.... but a plant none the less... keep in mind you cant see the tap root fully... but its basicly a 3:1 ratio of roots vs what you see above.

[9fingerleafs]

Looking healty and very happy. Like qwerty said a transplant will help them but don’t worry much bout that yellowing. If it gets worse just feed some nutrients

[Crow]

Yeah, the tops look happy but the underside is going yellow. I hope you are right. Will repot this weekend.
Thanks for the help.

Crow

[D.A.A.S.69]

Yes indeed they need transplanting very soon, wouldn't surprise me a bit that they are root bound, or very close to it.
Good Luck with them.

[Crow]

OK - I'm back with an update. NOT JUST YELLOW TIPS but full yellow lower leaves at this point.

Yesterday I went ahead and transplanted my yellow/green seedlings from the 3" cow pots to 2 gallon fiber pots and into the organic COAST of MAINE - Stonington Blend soil.

Based on therapies suggested above - I left the yellow leaves alone - to fall off as they wilt AND transplanted with the expectation that my seedlings were possibly root bound.

As you can see from the photo they were not root bound though they were still too dry. I'm pretty certain that under watering has caused the yellow leaves. I received Nebula's tutorial email today to remind me how to diagnose the cause of yellow leaves. Will also need to start paying attention to PH.

Now transplanted to 2 gallon pots and moved to my dedicated grow shed under 2 - 600 watt LEDs. I think this grow shed can be considered an indoor/outdoor hybrid grow situation. The room walls are insulated but the flooring is open to the ground. The floor boards are spaced, like with deck boards and the room sits on post about 7" off the open ground. Also the roof is not insulated and the eves are open to the air with screening to keep out insects and critters but with good air flow from the floor through the roof.

I have also installed some fans and will do my best to control the room temps at the plants to 80° F or less - to 74° F. The room is 4 feet deep x 7'-6" wide and just barley 8' tall sloping to 92". Barely room in there for full height grows, so will stick to low growing strains and training to keep my grow heights to less than 6'.

The LEDs require a minimum of 24" to the plants. At this stage the lighting company recommends 36" to 40". That's why they appear quite high off the plants. Eventually the plants will be in # 8 or # 10 "Smart Pots" set on the floor of the shed. Will only have room for 4 plants at the max. If the height gets out of control, I figure I can cut out holes in the floor (or remove most of the floor) and dig deeper into the ground below, to gain another 12".

Any advice?

Do you see problems or issues that I have overlooked - especially as regards to my yellow leaves???

Thanks for any help.

Crow

Here are my photos of the plants as of yesterday

• The first two show examples of the yellowing. The tops are nicely green but the underside leaves have been yellow for the last week.

• 3rd photo show that the plant was NOT root bound

• 4th photo is my grow shed

[Jr83]

It could be possible even water a little every day could over water since they where in a small container .u really need to water to 20% run off. and then wait a couple days.i loved my first 2 grows to death lol