Hi folks,
Complete beginner here, getting frustrated with trying to grow something that should grow like a weed!
My seeds (Royal Queen Seeds automatics) all germinate well (damp tissue method), and when their taproots are 1-2 cm long I plant them out in small pots, approx 0.5-1 cm deep. Compost is mgc24 “bio-hanf” peat-free brand. They grow, possibly a bit stringy, but maintain a nice green colour, on the windowsill. When they have another couple of pairs of leaves, after their cotyledons, I move them outside, to a SW facing patio with a wall behind them. It’s been warm, but rarely >30 C, and I’d say it’s been sunny enough - the rest of the garden is fine….
Then the plants stall - they get a few more leaves, never show any interest in e.g. the stalk branching, and turn a uniform paler green. They do not grow taller than approx. 10 cm, with my oldest plant from late May having started to grow a single tiny bud (is bonsai cannabis valuable :-) ).
The water here (Berlin) is quite hard, but still tests as having a pH of ~7. I’ve also tried watering with rain water and acidified (citric acid - it’s what’s in the Biobizz pH down) water.
I’ve tried Root Juice, Fish Mix and Alg-a-mic fertilisers from Biobizz, nothing seems to make any difference, and with such small plants it’s difficult to not overwater. I’d also expect the compost itself to still be providing enough nutrition for such young plants?
All help/suggestions gratefully received - thanks! Sorry for lack of a picture - for some reason it’s not letting me upload anything.
It would be helpful to get a picture of the roots, but a total WAG is you might be fawning over them too much and perhaps they are getting over watered. Just a guess though…
Roots should be white and bright.
Hard to give other input without pictures, but seedlings/early growth should be fine in normal soil, you really shouldn’t need to supplement so early unless there is some other mitigating factor.
Thank you! I’ve hopefully added a picture. I suspect that you’re right - every time I mention the plants my wife rolls her eyes….
I’m leaving the flower pot until it feels light, then watering well, and the water drains freely. The top layer of soil currently feels “sticky” after being watered a day ago - I also check that the top 1-2 cm is dry before watering. I’ll resist any further fertilisation unless the photo makes people think there’s a nutrient problem.
My thought was over watering or not enough light. Small plants can be really tricky to get right.
Thank you - yes, I’ve really struggled here - despite the pot feeling light and the top layer being dry, it turned out the lower levels were soaking. I’ve been (annoyingly, according to my wife :-) ) very careful to move the plants out of shade though, so hopefully that part isn’t a problem.
If you have extra seeds,.I’d go ahead and pop them. Trying to save a messed up seedling can be more trouble than it’s worth.
Just a heads up I grow mostly vegetables, have been an avid gardener for over 15 years so my advice will be generic and not specific to growing cannabis. In general I think cannabis growers over think something that is much simpler than it seems. After growing veggies for so long, I found that cannabis is so laughably easy to grow, its ridiculously robust, will handle all kinds of abuse and grows incredibly fast. Here is the little beast I grew two years ago
You mentioned you put them outside, how long ago? Did you re-pot them when you put them outside? They will need time to establish bigger roots when you replant them. Are you growing anything else outside that is doing well or just the cannabis? A picture of the leaves will tell a better story, green has lots of shades and a light green means stress. If you gave it lots of nutrients and you got no response that is bad, either you will over feed it and stress it out (Very hard in my experience) or it will take it up and burst into growth. What this tells me is your plant CANT take up the feed in the soil because the dirt is too wet. How often do you water the plant and do you check the soil to ensure its dry before watering? Has it rained a lot? Over-watered dirt will kill your plant because it cannot get the nutrients it needs, it needs to be damp but NOT wet or the roots aren’t effective.
Thank you for the detailed reply - I’ve previously had no problems with “normal” plants but it really does sound like I’m killing these with love. Very, very jealous of your beast!
That is severe nitrogen (N) deficiency.
Three ways this happens:
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Not enough N added in fertilizer/compost etc.
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Organic matter with high Carbon:Nitrogen ratio locking up the N as it decomposes. In order for bacteria/fungi to break down plant material they need a C:N ratio of 30:1. Wood chips are 250-500:1.
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Over-watering. Bacteria convert all types of nitrogen in aerobic conditions to NO2- and then NO3-. Both NO2- and NO3- are highly water soluable and leach out of the pot quickly. In severely waterlogged soils anaerobic conditions occur. This triggers bacteria to convert NO3- to N2 gas and it returns to the atmosphere.
Thank you also for the very detailed reply - from those options I think 1) and 2) are unlikely in my case - it’s a pre-fertilised compost designed for cannabis and should still have enough nutrients (plus during various stages of panicking I added N-Rich fertiliser (Fish mix) and no change occurred). This leaves 3, which has been the suggestion of others as well - although from your explanation I’ll be careful about reusing compost and will use new compost and add further fertiliser if required.
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Those leaves look too light green, the plant is stressed. How often do you water the plant and how much do you give it? What is your metric for ‘enough’? Do you let water sit in that tray? I would just start by watering it 1/3 as much as you currently do and see how it goes, the leaves will wilt if you are stressing it due to lack of water but in my experience cannabis can handle serious drought stress, they’re champs.
Thank you again :-) I have been watering when the pot is light, and the top cm or so is dry, not letting it sit in water but watering enough that the water runs through. I’ve spare compost and perlite, so I’ll try quickly repotting, in case the soil’s now too compressed/waterlogged, then follow your suggestion re the watering frequency and try and forget about the plant a little!
Healthy plants need to be ignored just the right amount in order to thrive. Over watering is harder to recover from than under watering, for what that’s worth. The leaves still look good, albeit a little light on nitrogen, so a full recovery is totally possible. My current grow experienced complete root loss at about the same age due to an equipment oversight, and you would never be able to tell with how lush and green it is now.
You got this!
Learning to ignore my plants just enough was the turning point in my weed growing career. Excellent advice.
Great, thank you! Just have to hope I can rescue them before the “auto” part kicks in - it would be a shame to have to start again.
Multiple problems, mainly your roots. Probably not enough drainage and over-watering. Your roots are not able to breath and are under-developed. Now they can’t use all the nutritions the plant needs.
Get some good substrate, maybe even invest in bio bizz. At least perlite for your substrate. And re-pot asap. Its not too late, she will be back if you give her the chance.
Nochmals vielen Dank! Thank you again - I’ve got compost left and some extra perlite so I’ll mix some more in and repot now.
If you have a bigger pot, use it! Cannabis needs a lot of space for the roots. They are “Tiefenwurzeler”, not sure how to translate that one ;)
Deep rooters! I’ve just done some repotting before reading your reply, actually downsized slightly and added a lot of drainage as the roots were basically nonexistent and I’m trying to force myself to not overwater now. When the colour returns and the repotting stress has passed I’ll follow your advice and go directly to the “final” pot size.
I’ve always read that autos like to be in their final pot size from the beginning.
Thanks - more compost has now been ordered :-)
I think we need a few pictures of your plant for a proper analysis. It sounds like they either finished their pre-flower stretch or its just the pot size. How old are they?
You are invited to visit us german growmies at [email protected] if you want to talk about it in german. We also have a very active Matrix room.
Danke, obwohl ich Engländer bin und mein Deutsch noch nicht sehr gut ist, werde ich mich trotzdem anmelden!
I’ve hopefully added a photo as a reply to my original post. That plant was planted out on the 2.7, seedling appeared on the 5.7, it’s a Purplematic Auto.
Any possibility there are bugs eating the roots of the new plants?
I’ve sometimes had that as an issue preventing proper growth in new plants. Older plants with properly established roots don’t care as much, but new seedlings making new roots can have their roots destroyed by bugs.
https://ortho.com/en-us/garden/how-to-kill-fungus-gnats-indoors.html
