Newbie auto grower has made a total arse of his first attempt...

[Kausk]

93% humidty! Don't worry, I won't eat the room

Thats far too high for the low temps imho, plants cant really transpirate that way (VPD around 0,2). You should try to keep it in the 60% range but I can imagine its hard in your outdoor area. Starting new seeds wont help in this environment as they will likely develop the same.

 

[Cannaficionado]

My first question is how often and how much are you watering? Is there significant runoff? If you're growing in something with compost its almost certainly a peat based soil although some companies use coco in with organic inputs.

Its very hard to overwater plants in fabric bags with well aerated medium. This is a definite sign of overwatering. But I also noticed you said your light was 200mm above the plants, at what brightness? 100% that close is blasting them. If you wanna keep the lights at that height thats fine, but if your at 100% turn it down to like 30-50% brightness. At this stage of growth autos should be getting around 400-600ppfd. I like to keep my light at least 1ft away from the canopy preferably 18inches (it gives optimal spread for most LED fixtures). That's when I run my light at a higher brightness. If you dont have anything to measure your light intensity photone or ppfd meter both are offered on android and IPhone. You need a diffuser for photone which is more accurate in my opinion. A strip of paper to cover your camera lens will work or they sell a diffuser that clips over it for relatively cheap.

As for the watering before you sew your seed, fully saturate the pot you plan on sewing your seeds into. Wait a few hours or so for that water to hydrate every bit of that bag and get a feel for the weight. After your plant has established and gone into full vegetative growth (about 2-3weeks or when the leaves touch the edge of the pot) you can water when its about half that saturated weight, but dont let your medium dry back too much. It causes nutrients to concentrate in your medium and can lead to burn. As seedlings just try to maintain a decently saturated level to avoid stunting. I mist daily and water about 1 cup 4-6 days around the edges of the pot in 5 gallon containers. Also one more thing when your seedlings first pop up and until vegetative stage starts they only need 200-300ppfd. Also in peat based soils with organic or synthetic inputs avoid runoff, it washes out beneficial bacteria and fertilizer. A little bit is fine but if its just pouring out the bottom its bad, around 10-20% is preferable in coco mediums to asure the concentration of nutrients is staying consistent but you can monitor that more easily by measure ec of runoff compared to inputs, you cannot accurately do that with peat.

Hope this helps sorry for the lengthy response I just wanted to mention a few things new growers tend to struggle with.

 

[Coffeesynth]

Thank you for your very comprehensive reply! The compost I used is peat free. Nasty cheap pre-ferted supermarket stuff. I suspect that there is nowhere near enough aeration in it. I did saturate the pot when I started - but then like an idiot then kept watering every few days! But I suspect that my main problem was having criminally low air exchange as the seedlings grew. I was so concerned about limiting the extraction of valuable warmish air (there is a little heater in there) that I completely forgot all about photosynthesis and getting fresh CO2 in to replenish what they'd used! D'oh! What an arse. It's a wonder that they survived at all! I've substantially increased the extraction now to very roughly one change of air every three minutes. I grew for ten years before I had a break from it - I really should know these things!! They seem to be picking up since I turned up the fan controller

 

[Coffeesynth]

Oh, the TS1000 lamp is 300mm/12 inches above the tops. 50% intensity at the start but probably should have started at 25%, increasing up to 75% in veg. 100% for flowering, I believe

 

[Kausk]

I was so concerned about limiting the extraction of valuable warmish air (there is a little heater in there) that I completely forgot all about photosynthesis and getting fresh CO2 in to replenish what they'd used

I really dont think thats your problem here mate, very low temps and very high humidity is the bigger issue here. Just my opinion

 

[Cannaficionado]

Thank you for your very comprehensive reply! The compost I used is peat free. Nasty cheap pre-ferted supermarket stuff. I suspect that there is nowhere near enough aeration in it. I did saturate the pot when I started - but then like an idiot then kept watering every few days! But I suspect that my main problem was having criminally low air exchange as the seedlings grew. I was so concerned about limiting the extraction of valuable warmish air (there is a little heater in there) that I completely forgot all about photosynthesis and getting fresh CO2 in to replenish what they'd used! D'oh! What an arse. It's a wonder that they survived at all! I've substantially increased the extraction now to very roughly one change of air every three minutes. I grew for ten years before I had a break from it - I really should know these things!! They seem to be picking up since I turned up the fan controller

Yeah I doubt thats a problem. Im in full flower and I dont have my ventilation running 24/7 unless humidity gets out of control. I only mentioned lighting because of how close it was. But you're good there. CO2 shouldnt really be a limiting factor unless your area is sealed and air isn't being replenished. If its not sealed it would be hard to believe that those plants are cycling all available C02 in the air even if your ventilation isn't running much at all.

 

[Coffeesynth]

I really dont think thats your problem here mate, very low temps and very high humidity is the bigger issue here. Just my opinion

I'll have a word with the weather!

 

[Coffeesynth]

They are in a sealed box and there was virtually no air exchange. I was using a 4" bathroom fan running as slow as it would go! A hamster fart moves more air. We've now got the RkV100 on the job, running at a healthy flow

Yeah I doubt thats a problem. Im in full flower and I dont have my ventilation running 24/7 unless humidity gets out of control. I only mentioned lighting because of how close it was. But you're good there. CO2 shouldnt really be a limiting factor unless your area is sealed and air isn't being replenished. If its not sealed it would be hard to believe that those plants are cycling all available C02 in the air even if your ventilation isn't running much at all.thry

 

[Coffeesynth]

I'll be fitting a second fan controller in the near future and a relay to switch the fan between slow and faster for night and day

 

[BII]

Most tents have problems that they need to get rid of heat from the lights. Is your tent exhaust fan controlled by a thermostat, such as a thermostat outlet, so you maintain a constant temperature? Or is the shed so cold (and it's not even winter yet) that you need heat?

If you need to add heat, heat the tent, such as put small electric heater in there (running off a thermostat); don't heat the shed. Also consider adding insulation around the tent - even just draping blankets over it will help a lot.