Pinched Crowns - Bad seeds?


I couldn’t find any reference to this anywhere so maybe someone has seen it. Either that or I’ve hit the Bad Luck lottery, again.

I’ve sprouted a lot of seeds for my self and fellow growers and always sprout them in rock wool cubes right in the hydro. For three of the last four I;ve sprouted I’vecontered the exact sme thing. The sprouts pop right out and stand tall but then the crown never developes. So I wind up with a very nicely formed stem and a little bitty pair of leaves for about 2 days before they just croak and fall over.

You can see in the pics the progression of whatever is happening. I had one friend who mentioned scoring the seed case before sprouting but it appears to as if the seed case splits just fine and falls away. I’ve used the same process for 25 - 30 sprouts of both seed bank and local seeds. (All the ones that have flaked out have been seed bank seeds from different sources and 2 dfferent people so mishandling, mishap and contamination are pretty much ruled out.)


What are your temps?

To me it looks like maybe they peat plug is staying too wet and they are drowning.


With LED lights the temp range is 73F - 76F; RH is66 +/-3; Because I’ve got clones in the tent I’m currently running my clear side lights 24/0 and the multi spectrums at 12/12. When i set the seeds I presoaked the rock wool cubes for an hourim a bowlwhere I had added just a couple of drops of Grow Boost then just shook the excess watr out before setting the seeds in about 3/8 inch deep and closing the cube to hide them completely. One sprouted out in 3 days and the other in 5.

As I said earlier I sprout them right in the DWC reservoir with the water level just touching the bottom of the netty pot. With others I’ve done this way by the time they drop roots enough to pick up solution from the reservoir the water level will be 1/4 = 3/8 inch below the pot. I only mist wateer the seedlings when the top of the top of the cubes start to look dry (usuaally 2 - 3 times per week. A week after the sprouts emerge I mix the water I’m misting with to 1/8 th strength Grow Boost and keep misting until the seedling have dropped 2 - 3 roots into the solution. I then boost the mix getting up to full strength over some 4 - 6 feeding depending on how the plants react to the solution.

Thanks for the response and help, man.


Rock wool? I only see peat plugs.


(Head Scratch) Could be, I reckon. I bought 'em off Ebay. They’re Botanicare and were listed as “cut Rock Wool”. When I bought 'emI knew a hell of a lot less about this kind of growing than I do now, if that’s possible, lmao. I really have had very good luck with them up to these past few seeds.

I really want to get things ironed out, if I can, quickly. I’ve got some high $ seeds coming in the next couple of days and don’t want to whizz none of them away. If you know what I mean. So I really, really do appreciate every bit if help you and latewood have been sending my way.

Peace and good growing, brother.


As far as I know, rockwool does not look like that. As far as I’ve ever encountered, rockwool looks kind of like yellowish/off-white/grey-ish fiber glass insulation, almost, as it is molten spun rock minerals, and fiberglass is molten spun glass(aka pure silicon).

Peat plugs look like a woody fiber stuff that expands when it gets wet.

I’m thinking it has to be temps or the plug is just too wet. It really looks like damping off from the seedlings roots dying from being in an overly wet soil or media that becomes too anaerobic.

You could also try adding a good microbe inoculatant. But I think an inoculant alone is probably not going to solve your problem, but maybe.

And I’m thinking maybe to not use the grow boost at all, seedlings need no nutrients. I’ve not used the booster yet but I understand its pretty concentrated, maybe the seeds are dying from too hot of nutrients?


I just ran acrosss and replied to a thread in Ventilation. Temp and RH control have been biting my ass all along because all I had is a 4 in. in-line fan exhausting. Man I wish I had your post about needing a vortex or centrif. fan stapled to my forehead.

BTW, and I posted this in that thread, too, I found a vortex fan and carbon scrubber combo at Sears for $145. Let’s you kill 2 birds, yata yata.

That alone is going to kill 90% of my nightmares. So, thanks, man, more than I can say. (I also cagied some real Rock Wool and Coco plugs to find out which I like best.) And THANKS AGAIN!


I’m glad you found it, lol. I never can keep it straight who I’ve asked or told what to who, lol.


I hear you, brother. If I tried to keep track of all the stuff you and latewood do I’d be stark, raving bug shit. Hell I can’t remember the few posts I’ve made.

That said, hang in there, man. You guys are absolutely invaluable to idiots like me.


Getting temps down might help. Your reservoir is obviously going to be very close to the air temp in the enclosed space.

Your reservoir temps should be ideally about 69F in a DWC or other highly “wet” hydro environment, and almost never should be above 75F, you will start having lower and lower oxygen levels as you go much above 70F, and the roots need lots of oxygen. Usually 73F shouldn’t be a problem with enough aeration, and I have seen temps tolerated as high as 78*F with a ridiculously high amount of aeration

If you had success germinating while adding booster before, as it is so concentrated, maybe last time you were near the highest tolerable for seedlings and maybe this time even though it might seem you mixed the same strength, maybe it is too strong, or maybe the temps make the seedlings less tolerant of high nutes as well?

Anyway, some things to think about, hope this helps so you can get it fixed as soon as you get your new genetics.


Thanks Mac. Definitely some things I’ll take to heart.

I’ve already had as much an encounter with root rot as I’ll ever desire. A bit of good news there though. The plants that I jerked out of DWC clining to life by a thread went on 12/12 light schedule today. You can kind of get an idea of what that adventure has been from the pic in the thread below. Now if they just don’t hermie out on me from the trauma.


MC…You are so funny.

After reading through and having a chuckle or 2; Sorry. I know it can be frustrating. :smile:
Your starter plugs appear to be similar to RootRiot starter cubes. Made up of organic matter and bonded together to form a sponge like medium. You would be better off sitting them in a tray or lower the water in the DWC res. You don’t need all that water. I agree with what MacG said when he mentioned they could not thrive due to being wet for too long.

Never add Grow Boost to sprouts/seedlings. This will kill them fast. If you feel you have to try and supply any nutrient; The proper drop or 2 should come from the Bloom bottle, as Potassium is the mineral you want in order to establish strong roots.

Personally; I use Liquid Karma from the start, and I always have strong healthy plants. I hope we can get you on track my friend. Have a great day! :slight_smile:


Yes, they are definitely not rockwool. I have seen those other type starter cubes/pellets, the “rootriot” name brand or something like that, and yes they can stay too wet in a DWC as well, and they shouldn’t need a soak other than pure properly pH’ed water.


Yeah MacG, I’m finding out real quick that whatever the cubes are they ARE NOT what you want to set clones. They dry out on the outside even in a propogation tray. Take that coupled with their natural density and I don’t think young, new roots can ever punch out of them. I have a couple of smaller 10 day old clones in them now. Yhe plants themselves look beautifully green and hearty so there are some sort of roots starting in there but no sign at all of them breaking out. By 14 days if they haven’t gotten through the cube somehow or if the clones start to droop I’ve got to figure somehow to free the roots without killing the seedlings. Other clones I have started I used some Coco Coir cloning cubes and after 6 days a couple are showing some rooting already.

Looks like I better get good at cloning, too. It doesn’t seem like I’m ever going to get an order of seeds through Customs/Department of Agriculture in this lifetime. Three of 4 orders I’ve placed since March with different seed banks have been intercepted and the 4th just disappeared without a trace. Guess someone has to protect us from The Attack of the Killer Cannabis Seeds though.

Peace and Happy highs.


Latewood, MacG, anybody.

I finally got my hands on some more seeds and thought I was in the tall grass for sure. Especially when they sprouted out of the combo of coir and rock wool plugs in 2 - 3 days. It was not to be though and I can’t get my head wrapped around this at all. These seeds went into basically the same thing this whole thread is about. This time though I was very cautious about the water. That’s how I noticed that the plugs were drying out terribly. One plantling that was up still had the seed case attached which I removed, very gently of course. Examining the seed case I found it was dry and hard as hell. All the seedling displayed the same thing with the stems going thin and thready much like damping out. I doubt that it was damping out as I soaked the seeds for an hour in 3% peroxide prior to planting but there was still that spindly, twisting stalk just below the leaf clusters.

The cube drying is across the board though. I sprouted these plants in a propagation trayand had to mist the cubes 2 - 3 times a day to keep them from hardening. Hoping for some decent luck as I had had on some earlier sprouts I moved them the DWC bucket as soon as they shed (or I removed) the seed case setting the water level just so the aeration bubbles splashed the bottom of the netty pots and layer of clay balls beneath the starter cubes. The tops of the cubes and tops of the clay balls are still drying out though. One sprout died out in the propagation tray out before I could really do anything with it, one in a coco coir plug. When I pulled that plug out and tore into it, it was dry, dry, dry all the way through and even though it died the sptout had dropped a very nice, white and healthy tap root that only liked a 1/4 inch or so punching through the starter cube.

Anyone have any experience with a like problem… Or ideas on how to fix it.

A toke, a coke and a good joke—Three of the better things in life. Peace!