Help identifying reason for slow seedlings

[4d-Rock]

Hey all, I was hoping to get some insight from the vast knowledge that are roaming these forums.

I’ve completed 6 grows so far with an additional 2 going now but I’ve always had slow starters which I believe is why they have not yielded to their full potential. I can’t seem to pinpoint the problem but hopefully someone will notice through the details a flaw in what I’m doing.

My first 4 grows I will be excluding as there was way too many changed variables and deficiency issues to have any consistency. I’d like to focus on my two last grows, and the two current, as they have all been grown in the same consistent conditions. First, I’ll break down the setup and things that all the grows have in common, then I’ll give pictures of each plant at 21 days and any notes of differences between them. Maybe someone will identify where I’m going wrong, or at least where I can improve.

Setup:

2’x3’x4.5’ Grow tent
400W (200W draw) Roleadro COB Light (18” for seedling/veg, ~12-14” in flower)
4” inline exhaust fan with charcoal filter
6” clip fan for air movement
1 gal fabric smart Pots
Pro-Mix HP Mycorrhizae soil, soaked with water and 1mL of Pro-mix Root-Booster
Water source: Lake water which goes through a charcoal and UV filter. Typically, 6.5-7 pH and 70ppm out of tap but varies a bit with seasonal changes
Nutrients: Fox Farms Trio

Each seed was soaked for 24hrs with water and a bit of hydrogen peroxide, placed in a paper towel until the taproot is 1-2cm long, and planted in the pre-soaked soil. Once planted, they were placed in the tent on an 18/6 lighting schedule which I keep to throughout the grow. Typical tent temperature is about 22-25C during lights on, 16-18C on lights out. The first 2 grows occurred during the summer/fall months and had a RH of 40-55%, the current 2 grows were around 30% RH up to these pictures but I’ve recently purchased a humidifier to keep it closer to 50% during Veg. Additionally, I put plastic cups on the seedlings up to about day 10 to keep humidity up during the early stage.

Plant 1 - Random Auto Seed from Crop King Seeds
- Light watering at day 6, 8, 10, 11, 14, 18 with 100-500mL of plain ph’d water
- First feed was on day 21 (pic) with 1L containing 0.5mL CalMag, 1mL Big Bloom, 0.5mL Grow Big. This is about ¼ strength as recommended. Measured at 500ppm/6.2pH

Plant 2 – Red Poison from Sweet Seeds
- Light watering at day 2, 3, 6, 9, 12, and 15 with 100-500mL of plain ph’d water
- Watered with minor additions on day 18 with 500mL containing 0.5mL CalMag, 1mL Big Bloom
- First true feed on day 21 (pic) with 1L containing 0.5mL CalMag, 1mL Big Bloom, 0.5mL Grow Big. Measured at 575ppm/6.3pH

Now on to the two current grows (note: I’ve tried to tone down the early light watering’s)

Plant 3 – Black Cream from Sweet Seeds
- Light watering at day 8, 10, 14, and 17 with 100-500mL of plain ph’d water
- First feed was on day 21 (pic) with 1L containing 0.5mL CalMag, 1mL Big Bloom, 0.5mL Grow Big. Measured at 530ppm/6.5pH

Plant 4 – Amnesia Auto from Canuk Seeds
- Light watering at day 8, 10, 14, and 17 with 100-500mL of plain ph’d water
- First feed was on day 21 (pic) with 1L containing 0.5mL CalMag, 1mL Big Bloom, 0.5mL Grow Big. Measured at 530ppm/6.5pH

Overall, I know they aren’t severely stunted, but they sure don’t come close to what I see in other peoples grow journals by day 21. Hopefully someone has some ideas or suggestions that I can try out on my next few plants. Also, feel free to ask additional questions if needed.

Thanks and happy growing!

 

[LittleMT]

As to what you are doing wrong, I don't know, maybe nothing, to me doing wrong would be the seedling dieing….

I can tell you I have a regime for my seedlings. I don't have any pre-soak germ method, I just take the seed and plant 1/2 inch deep in a mixture of Fox Farm OF and HP with some Coco Loco..... I count the days of life when the seedling 1st sprouts, that to me is day 1. For the first 6-7 days I have my seedlings under a Walmart great value led 5500k 15.5 watt bulb in a desk lamp with the diffuser removed. I shine this light maybe 5 inches from the seedling 24/7 and I watch her closely, any signs of stress I will take the light higher, typically they love it. I don't feed a damn thing other then Optic Foliar Overgrow but I do add microbes, products such as Recharge, Nitryx, Armory, Forge.... I focus on building a strong microbe community for the 1st 3 weeks. I keep my soil moist with light waterings…. I use this technique when I want fast growth and maximum maturity. I have other grows, some on a large scale where we just rely on overhead cobs, the seedlings grown under these conditions are still healthy but much slower then my 'seedling nursery' as described above.... The seedling stage IMO is these most critical as it sets the stage for what is to come....


With the above I have had seedlings very well developed within 7 days of life. Here is a current Mephisto seedling in the nursey getting great care...

 

[bad dragon bzzz]

i think light and air is more important than humidity.my cups come off end of day 1 give it a try possibly a lil too much water early on to.
good luck n keep er lit

 

[4d-Rock]

@LittleMT Thanks for your info! I don't think I'm at a place where I'd like to start making soils or playing around with additives too much if I can help it. I do like the idea of a seedling nursery with a specific light. I have a space bucket which uses a photographer light ballast and 4x 10w LED bulbs with the diffusers cut off. That might just be where I start my seedlings. I would agree that seedling stage is very important to get the full potential of a grow, hence why I'm trying to get it dialed in better.

@archie gemmill Thanks, I figured i may have watered a bit much. Not so much to be significantly detrimental, but enough to slow it down a bit. I tried to lift the domes daily to give fresh air but I'll likely minimize their use for my next grows now that I have a humidifier to control the tent RH.

Am I possibly feeding a bit late? To my knowledge, Pro-mix HP is void of much for nutrients, and although I haven't noticed any of the plants begging for nutes I wonder if starting a bit earlier with a 1/8-1/4 strength might give it a kick.

 

[bad dragon bzzz]

i dont know anything about pro mix hp.i use biobizz lightmix,its not got much of anything in it,and i start light feed from day 10.
good luck n keep er lit.

 

[Waira]

-- Pro-Mix is devoid of nutes, so feeds start within a week, mild dosing as you did,.. then ramp up gradually,.. the last round here with no feeds until day 21 is starvation level feeding, they stay small.... T's could go up some, night especially,....
Note that Big Bloom is very very weak stuff, good, but I consider it a supplement, not a real feed... NPK #'s are in the decimal range! Grow and Tiger are the base nutes....
Consider getting other products, like humic-fulvic, Si, inoculants, Ca-Mg, or switching to a true soil not soilless which Pro-Mix is,... this is about what exactly is in there, soil in a complex blend of things, soilless is very simple,.... Inoculants with assorted microbes will help build a better root system, Si has a lot of benefits (look it up here in Reference-- ditto for humic-fulvic)...
At this late stage, those plants will not get much bigger during bloom, which is going to start soon,... but feed then ASAP and see what you can coax out of them; start with1/4-1/3 str. dose and see how they react,....

 

[4d-Rock]

Interesting. Thanks for the insight @Waira ! I didn't really think of the Pro-mix as a soilless medium but I suppose the term "soil" would suggest that there are nutrients and other components to it. Quick question regarding this then, if it is indeed Soilless, should I be ph'ing my water to the soil levels, or the hydro levels based on the nutrient uptake charts? I try to keep around 6.2-6.5pH and I didn't seem to have any pH problems in the plants above later on.

Being new, I have also been erring on the side of caution on my nutrients as the forums "less is more" motto has told me. I can see where by day 21 the plant would be looking for nutrients. I was waiting for the plants to speak to me as I have yet to see more than a bit of yellowing on the cotyledons. Next plant I will try my first weak feed after 1 week.

I have been using Big bloom as a supplement that gets added with every feed, then Grow big and Tiger Bloom being the main nutes. I have also been adding CALiMAGic at a general 1mL/L throughout the grows. The weird thing with that is that everyone says that it shouldn't raise your ppms by much, this one bumps it up (1mL in 1L of water increases ppm from ~70ppm to 400ppm) and I worry it could cause burning when adding other nutes. I said before I'm not too interested in playing around with soil mixing or composting but I'll look into the supplements you've suggested.

The plants have taken to the first feed pretty well and I will continue watching and training them as needed. I'm tempted to start a 3rd to give some of these ideas a try.

 

[RivetGrrl]

The plants aren't showing signs of deficiencies, but the previous advice to feed more can't hurt. I'll often increase feeding with a new nutrient until I see tip burning, and back off a bit from there.
The biggest thing that stands out to me is the night time temps may very well be too cold, and that can really stunt plant growth.
Are you in a basement? On a concrete floor? If so, can you put the tent on something that can insulate between the floor and your pots, it would make a difference to start troubleshooting.

 

[4d-Rock]

Cool, thanks @RivetGrrl
I had thought the temp was a bit on the low side but wasn’t sure on how much effect it was having. @Waira mentioned the low temp too. I haven’t done much about it but now that you mention it, it is in a basement on cement.
I have some things to put it on to insulate it and will see how that does for the day/night temps.

That makes sense for the nutes, as long as you don’t really burn them the first time before getting a chance to tone it down!

 

[STILLSMOKIN]

Too much water. I soak my medium the same day I drop seed in water. 24hrs tap or not its in the dirt, 1/2 deep cover over with dirt. Lay ziplock bag on top, wait for bag to raise. I usually water every 5-7 days only watering outer edges of medium until fans are touching sides of pot. If center feels too dry you can give it a little here and there.