trouble germinating in rockwool/roots not growing out of cube

Hi Guys,

So this is something i've been struggling with recently; (have searched and researched alot of similar posts, but nothing the same),

i've read and read and read about the process, and recently decided to put it into action, to which every single one germinated, then came straight through the top of the rockwool within 3 days of being planted.

the guide i've read states to plant the cube into the medium as soon as the root comes through the bottom.

im currently using a custom built top drip system which iv used in the past (Cleaned of course) 45 litre storage box with a pump inside leading to 4 ring drippers, on top of 5" netpot full of hydroton.

i've PHed water to 5.5 (raises to 6.5 over 24 hours to which i re-calibrate back to 5.5, lather rinse repeat), with around 300ms (EC) of 150 ms tap water and 150 ms of just grow (3 part mix of grow, micro and bloom).

i've rattled my brain for days now, some of the roots are going brown and dying off, some are just not progressing at all. once into the system, the root just stops growing. the rockwool also acts as a wick and becomes completely wet so it seems the root is putting no effort into stretching because its getting what it needs already!

Strain: Fruity Chronic Juice,
germinated in: Rockwool,
transplant into: hydroton net pot, drip feed DWC hybrid system.
Water: tap water, 150ms EC from tap, 7-7.5ph adjusted accordingly to 5.5

Thanks in advance for all the help in advance

Bbblz

Hey buddy, firstly I would not be pH'ing water for germination it can have bad repercussions slow growth, acid bases are not great with seedlings. The 7.5 water is super fine or just use some bottled water or distilled water.

What is the temp of the water and room?

Also how compacted is the rockwool one of the most common issues is rockwool can be quite a stiff medium for young sprouts to make it through.

I would not be using any nutrients to germinate at all apart from something like 'my first feed' designed for germination but to be honest water is fine

Are the seedlings strong? If you have good growth on top then they will make it through if it is not compacted do you have any pics?

The brown roots are nutrient burn or base burn from you pH'ing

thanks for the prompt reply Sandgrouper,

the guides always state when germing with rockwool, to put water and rockwool into tub, let them climatise, then to ph it down to 5.5 because rockwool is too alkaline. are you saying to leave it around 7.5 until the roots come out?

i forgot to mention, iv not used any feed up until yesterday, iv just been using ph5.5 water. they come up looking fine, first true leaves set. only 2 so far have shown their roots at the bottom, one of which was the youngest (i started with 3, then when they germed, i did another three, then another three). so one has took 6 days to show taproot, some of them have took 2 weeks and still not showing tap root.

also with regards to the compacting rockwool, i soak for 24 hours then "baseball throw" to get rid of excess water. maybe i did this 5-7 times each cube to get rid of as much water as possible.

i've not took a temp reading of the propogator, I will do this later if i can find a spare thermometer. i would guess around 75f because its slightly warmer than unwarmed. (im using a heat mat underneath it).

sorry i've got no pictures, bit paranoid about this lol,

Bbblz

Hmmm - the temp should be more than fine. I have just moved to a super cold climate and had no germination in my rockwool until I put a heater in the room now got too many heads popping out. It is true that rockwool is alkaline but to be honest I am a bit rough with germination, I simply use a small prop box flood the fk out of it drain off the excess pop the seeds in and flood the top if it gets a little dry.

I don't overly worry about the roots I wait until the seedlings are looking strong then straight into the growing medium. I am not that kind to plants but have been growing a long time. I think the only issue you have is the roots browning off which does sort of indicate a burn of some kind

I do think you could be worried about nothing, cancel the nutrients if they look strong throw them into the medium in the rockwool and run a super low nutrient even no nutrient for another week, or very low PPM say about 100PPM

so most of the seedlings died, they just stopped progressing and the root tip browned. i believe I could have burned them as you say with the acid or the low strengh feed or both. 2 of them have survived, and are now in the clay pebbles, being fed 15 mins 4x a day, on plain water (non ph'd) and hopefully are growing.

there is no roots coming out of the bottom of the 5" net pots, but they look like they are thriving.

i set another 2 off in rockwool soaked in normal tap water, approx 7-7.3ph, they took 1 extra day to germinate, but the root was showing before the seedling was! so what iv done this time is pop them in bigger rockwool blocks (5"?) as to provoke a good root structure before planting into clay pebbles or even attempt another method like ebb n flow or nFt.

my problem is that I am far too curious and impatient so 2 of the first rockwool cubes got pulled apart to check on the roots, and they keep getting picked up to check the roots at the bottom.

with the latest 2 that popped, i have left them alone in the big rockwool, i can't attempt to pick up the 1inch as this may damage any roots pushing into the bigger rockwool.

its a shame that the little fvckers can live for a week in wet RW without progressing before they shrivel up. i wish i could see through RW lol!

Thanks for the support Sandgrouper. could you please keep an eye on this so I dont fvck it up tooo much?

BbblZ

It happens, don't stress over it.

Patience and not screwing with their buzz has to be the single biggest technique for successful grows.

Germination is greatly dependant on so many factors, from temp, humidity too strain dependant. I have some sativa seeds in at the moment which compared to another strain are really slow to germinate, sit there for a week and then some before showing their heads at a minimum.

Roots at the bottom or not I don't worry about, they go from a propagation tray into clay pebble in water farms, if the seedling looks strong enough still only two leaves then off to the water farm. If it looks strong enough chances are when you do remove the plug there are roots, if not it is strong enough anyway.

If you have good temp, humidity, fresh air, circulation, and it is stable then if you stick seeds in rock-wool and keep em damp their going to germinate.

Move em once then leave the fuckers alone, apart from any training, defoliation if strain needs it or light ain't bright enough for penetration.
If it does not need to be cut, then don't cut it, this includes but I'll just snip this just to see how it is. NO! - enjoy the aroma

Use some well known Nutrients personally I like Canna, predictable and good quality. Don't buy into all these big bud formulas, learn what your strain wants and why and if needed there are additives in most ranges like the Canna range.

Remember the biggest buds may not be the best buds or taste the best, it's all about quality than quantity.

Enjoy

BBB,
I think 5.5 is too low...even for adult plants. Hydro does well at around 5.8. Coco growers sometimes use 5.5 but that's coco. And like Sg suggested...just use un-phed water for first couple weeks.

And rockwool is fine for hydro grows. I've used 1" squares for E&F clones. But you've already discovered that the rockwool holds lots of water...so why on earth go to 5" cubes.

Since you're top watering...you should be fine to put the seedling into the hydroton fairly early. Keep the humidity up until the plant gets established.

And quit messing with them...taking the blocks apart and such sh#t. You know that you're harming them so why do it?
JD