What's new
  • Happy Birthday ICMag! Been 20 years since Gypsy Nirvana created the forum! We are celebrating with a 4/20 Giveaway and by launching a new Patreon tier called "420club". You can read more here.
  • Important notice: ICMag's T.O.U. has been updated. Please review it here. For your convenience, it is also available in the main forum menu, under 'Quick Links"!

Seedlings not growing past the cotyledons

Tactical

New member
I have been growing for 6 years and have never had any problems like this.So my situation is this:I took a 2 year break from growing for personal reasons and decided to get back into it last month.I started germinating seeds using the paper towel method.The seeds i used are about 3 years old and were stored in small baggies in a box i left in a drawer.The seeds are an unknown strain that i was growing before and had no problems.
The setup:After trying to germinate 20 seeds i had about 50% sprout the tap root.After the seeds sprouted i moved them with tweezers into rapid rooters and put the plugs under a dome with 60 watts cool cfls just above the dome.As they sprouted i opened one of the vents to allow some air.i also took the dome off once a day for about 30 minutes and then put it back on.I watered the plugs when they started to dry with RO water with 30 ppms of sensi grow a+b.I checked for roots going through the plugs daily.The sprouts seemed to be growing slower then i am use to i just figured it was because of using older seeds.A couple days go by and i see 3 sprouts shooting roots through the plugs but still dont have a first set of true leaves. so i move them to my RDWC system and fill around them with hydroton. I put my 400w hortilux super hps in a cool tube at 20" above them.In my res i am running 150 ppms sensi grow a+b and 1ml per gal of dutch master zone to prevent any root rot with a ph of 5.8.I keep my water level 1" below the net pots and top water when i see the plugs start getting dry.The temps of the rdwc room are at 73 degrees F lights on and 64 degrees lights off at canopy level.I am running 18/6 light cycle.
the problem:The plants moved to the RDWC grew slow and i figured it was them growing more roots but i still did not have a set of healthy first true leaves they were very small and mutated.I waited about a week and there was growth but very very slow.One week after that one plant starts to pick up growth ALOT faster then the others and has grown roots down into the water.The other 2 are still growing very slow and their cotyledons have started to yellow even though they have tiny first sets.At week 3 all of my seedlings still in the dome have not shot roots and some start growing mutated first sets and some have yellowing cotyledons and tiny first sets so i move the dome into my rdwc room on a piece of wood so it doesn't get too cold from the cement floor further from the 400w hps then the ones in buckets.At this time i have one plant that is starting to grow normal but still small and 2 seedlings in the other buckets that dont grow much at all.All of my plants seem to be severely stunted and i am not sure why but i have some ideas.
#1 i am growing old seeds
#2 it is a bit colder in the grow room.
#3 i am using older rapid rooters and some in the bag had a little white mold and i treated the rooters with an h2o2 bath and sterilized before planting.
#4 humidity is at 24% in the room but i have grown in that humidity before with the same seeds.

Has anyone ever had anything like this happen to them or does anyone have any ideas as to what is happening?
 

Dropped Cat

Six Gummi Bears and Some Scotch
Veteran
#1 i am growing old seeds
#2 it is a bit colder in the grow room.
#3 i am using older rapid rooters and some in the bag had a little white mold and i treated the rooters with an h2o2 bath and sterilized before planting.
#4 humidity is at 24% in the room but i have grown in that humidity before with the same seeds.



1. Seeds are okay.

2. Find a way to keep seedlings warmer,
a thermostatically controlled seedling mat is a must
for cooler grow rooms.

3. Likely introduced pathogen with them old crusty plugs.

4. Low humidity a non issue.

Number 2 and 3 need to be adjusted before you waste more seeds.

I would get new plugs or at least some seedling mix,
and the seedling mat with temp control.

Good luck, we're all counting on you.
 

Tactical

New member
Thank you for the advice.I just ordered some new plugs and a heat mat with a thermostat.i also bought a humidifier to try and keep my RH higher.I will update the thread and see if that solves the problem.If it does maybe it will help someone having the same problem i do.
 

pop_rocks

In my empire of dirt
420giveaway
dropped cat has got you heading in the right direction

why did out change out the cfl?
/60w is respectable for seedlings, i would have added a bulb

"I put my 400w hortilux super hps in a cool tube at 20" above them."
hps bulbs are usually used later in flower and arent ideal for early/ vegatative growth
/it has to do with the spectrum of light produced
can your ballast run MH bulbs?
 

Tactical

New member
i have a 400w mh i can use but the hps produces more light so i thought it would be better because its the hortilux which is supposed to have some blue spectrum in it.My ballast is a solistek 1000w digital ballast.should i switch out the hps for the mh?The mh i have is just a cheap bulb.
 

pop_rocks

In my empire of dirt
420giveaway
once you get your seeds going, use the MH bulb for several weeks to get the plants going
you can start at a height of say 20" and lower the bulb once the plants get going
when they are ready to flower, then switch to the hps
 

Tactical

New member
Changed the bulb to the 400w mh and started germinating new seeds.rapid rooters should be here in 2 days so by the time they sprout i should have the plugs.My one question is should i water the new rapid rooters with any nutrients or should i just water with ro water with a ph of 5.8?
 

Latest posts

Latest posts

Top