Slow Seedlings

Hey folks, I'm still struggling to dial in the seedling stage and I find that my seedlings either pause (likely because I adjusted something in the environment too drastically) or they just take a really long time to get going once they pop. I've shared a photo from this morning - all of these plants are roughly 5 weeks old (except for the small solo cup in the back - that's prob about 3 weeks old and still pretty measly). The only one that seems to be tracking at a normal pace is the Maui Waui on the upper right - all the others feel small for their age and I've got the Northern Lights Auto in the upper left already flowering so I prob won't get much of a yield with that one.

Here is my setup:

Spider Farmer 2x2 tent
SF-1000 LED light
Temps typically in the 70s
RH typically 65% - 80% (though at 5 weeks it's now 55% - 65%)
Solo Cups: Purple Cow Organic Seed Starter Mix (20% Perlite + 1 tsp of Dynomyco)
Pot upgrade: FFOF (20% Perlite + 1 tsp of Dynomyco)
Chlorine-free water ph at 6.5

Is it possible that too much water will stunt them? I didn't kill anything, but I've def been a little more frequent with the waterings than necessary and have forced myself to wait an extra couple days until they really look thirsty since I noticed a bit of drooping/lightening up and leaf-edge crispiness here and there.

I expect the slowness I'm seeing is pure user error so any tips are appreciated, but I'm also curious if anyone has any suggestions on things to feed seedlings that would give them a boost in the first 2-3 weeks? I've seen some natural-based products in the past (maybe a seaweed thing I can't remember the name of) but I try to grow organic so I let the plants do their thing and don't top dress until I need to...

Based on the node stretch - im gonna say light too far and or too weak ( pics ) No lateral growth ( sides ).

Also other plants look a little light on food.

Budzbuddha said:

Based on the node stretch - im gonna say light too far and or too weak ( pics ) No lateral growth ( sides ).

Also other plants look a little light on food.

View attachment 5297302View attachment 5297303

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Yes at one point early on I thought the light was too close since they were all fairly squat so I moved the light up and then Northern Lights stretched so I knew I went too far.

I have also had a hard time figuring out appropriate light strength and may be not have been going strong enough - any opinions on the PPFD for seedlings? Right now I’m at roughly 300 but should that be higher for 5 weeks old?

I re-potted these all in FFOF about a week ago so food shouldn't be short, but maybe worth throwing in some EWC?

Your using a 100 watt led light? I use a lux meter not a ppf meter so i cant really help but i have seedlings right know / i also have a 100watt led light and i keep my light 6 inches above my seedlings on 25% power if my plants were as big as yours id keep my 100watt led light about 10 inches above the plants on 100% power good luck

secretmicrogrow420 said:

Your using a 100 watt led light? I use a lux meter not a ppf meter so i cant really help but i have seedlings right know / i also have a 100watt led light and i keep my light 6 inches above my seedlings on 25% power if my plants were as big as yours id keep my 100watt led light about 10 inches above the plants on 100% power good luck

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I appreciate it! Can't remember why exactly I went so conservative with the lighting in the first place - might have been misinterpreting too much water for light burn. I've turned up the lights a bit into the 500 PPFD range (30k+ LUX) and will monitor closely in case that is somehow too much for them...but from reading up on light intensity again they should be fuckin fine.

Question: would not enough light create symptoms that are similar to overwatering or N deficiency (e.g., lighter green/faint yellowing of leaves)?

jimbonorman said:

... I've turned up the lights a bit into the 500 PPFD range (30k+ LUX) and will monitor closely ...

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500 PPFD is fine - and plant your size can handle even higher intensity. I set my lights for ~630 PPFD when the plants are in VEG and turn that up to ~950 when the plants are in BLOOM.

jimbonorman said:

... Question: would not enough light create symptoms that are similar to overwatering or N deficiency (e.g., lighter green/faint yellowing of leaves)? ...

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Light is your primary food source so too little light will produce effects that resemble deficiencies more so than the overwatering leaf droop. Smaller leaves, slower growth, not a very healthy green colour ...

And even more telling is what @Budzbuddha mentioned above - excessive node spacing. Node spacing is usually ~2" so when you see nodes spaced around 4" to 5" apart you need to give your ladies more photons.

StareCase said:

500 PPFD is fine - and plant your size can handle even higher intensity. I set my lights for ~630 PPFD when the plants are in VEG and turn that up to ~950 when the plants are in BLOOM.

Light is your primary food source so too little light will produce effects that resemble deficiencies more so than the overwatering leaf droop. Smaller leaves, slower growth, not a very healthy green colour ...

And even more telling is what @Budzbuddha mentioned above - excessive node spacing. Node spacing is usually ~2" so when you see nodes spaced around 4" to 5" apart you need to give your ladies more photons.

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Makes a ton of sense - thank you!

You asked one question about overwatering and yes...absolutely...overwatering can cause a ton of issues that can resemble other things. Water to runoff and dont water again until the pots are almost dry. I never use a meter or the "push your finger 3 inches into the soil" technique. I go strictly by the weight of the pots. Getting your watering routine down is probably the MOST important thing.