Rock wool and seedling tips?

BigBloomingBuds · Mar 25, 2021

Hello!
This is my first time using rock wool and also my first time popping seeds. I am a little more than a week in and so far things look pretty good on most of them but other look like they are pushing themselves out the top of the rock wool. Has this happened to anyone before? Any tips?
Also any tips on rock wool watering would be helpful. All I keep reading is don’t over water but that is such a vague statement when I am also reading water everyday.
Thanks for your help!

gorillaglueaaron · Mar 25, 2021

@Dirtbag

BigBloomingBuds · Mar 25, 2021

Not sure why these didn’t attach the first time.

gorillaglueaaron · Mar 25, 2021

Oh I think I might be able to help with that actually. When they get all leggy like that, it means they need more light.

BigBloomingBuds · Mar 25, 2021

gorillaglueaaron said:
Oh I think I might be able to help with that actually. When they get all leggy like that, it means they need more light.

Thank you!!

gorillaglueaaron · Mar 25, 2021

What are you doing for lighting right now?

Goodthingsgrow · Mar 25, 2021

Hey BigBloomingBuds.
Migrating seeds do occur. It’s the loose make up of the rock wool.
Did you cover the hole well once the seed was planted?
Unless you just watered, your cubes look pretty wet. They need a good shake to get the water out. They should be moist not soaked. Too much water won’t let the oxygen in. Drain the excess water from the tray so they’re not wicking and staying wet.
Avoid misting when the lights are on too. Could fry them.
Hope this helps at least a little.

BigBloomingBuds · Mar 25, 2021

gorillaglueaaron said:
What are you doing for lighting right now?

They are under the seed sprouted dome and I’m using the nano tech T5 feflector light that comes with it. But I could add in the rock wool trays to lift them up.

Moe.Red · Mar 25, 2021

You are going to need to add in some dry back to your watering. If the rock wool is always wet, roots don't form properly. If you have roots going all thru the rock wool they don't have a way to lift up. You have some there that I'm afraid are not going to make it.

Here is what I do if it helps:

Soak seeds overnight in water. Tap water is fine. This will get the juices flowing, and is a step that I have found helps to germ even the hardest seeds.
Then put them on a paper towel slightly wet for another day. At the end of which you should see the seed cracked and the direction of the tap root can be determined. They do not all come out in the same direction, some will curl up and shoot for the sky, others will head down.

Open up the hole on the rock wool a bit so that you are not fighting to get the seed exactly where you want it with the root heading down. Now scrape the rock wool to close up the hole at the top and hug the seed in place. Put them in the dark with a small amount of water left in the rock wool, bit not a pool in the tray. If you use a dome, open the vent holes.

Soon, the first seed will break the surface and cotyledons will unfurl. This is the time to add light, even if not all seeds are up yet. If you wait too long, this first one will get leggy and maybe even fall over. You can add light and it will not hurt the others since you closed off the top of the hole in the rock wool.

Adjust your light so that the first one stops growing taller by more than a small percentage. The job now is to force roots down, not stems up.

Once you have first leaves on all you can start to slowly bump the lights up a little a day. Wait until you have a strong root structure coming out of all the rock wool bottoms before transplanting. You may be doing a few each day as they might not grow at the same rate.

Thru all of this, you need to have a dry back period every day. Water from the bottom, not directly on the rock wool. This will encourage roots to grow to seek water.

There are no nutrients needed for the entire germination process.

As far as temps go, that has a big influence on growth rate and success. If you can put a seedling heat pad under and make sure they stay around 75* or so, it will all work easier for you. Too hot or too cold will give poor results.

BigBloomingBuds · Mar 25, 2021

Moe.Red said:
You are going to need to add in some dry back to your watering. If the rock wool is always wet, roots don't form properly. If you have roots going all thru the rock wool they don't have a way to lift up. You have some there that I'm afraid are not going to make it.

Here is what I do if it helps:

Soak seeds overnight in water. Tap water is fine. This will get the juices flowing, and is a step that I have found helps to germ even the hardest seeds.
Then put them on a paper towel slightly wet for another day. At the end of which you should see the seed cracked and the direction of the tap root can be determined. They do not all come out in the same direction, some will curl up and shoot for the sky, others will head down.

Open up the hole on the rock wool a bit so that you are not fighting to get the seed exactly where you want it with the root heading down. Now scrape the rock wool to close up the hole at the top and hug the seed in place. Put them in the dark with a small amount of water left in the rock wool, bit not a pool in the tray. If you use a dome, open the vent holes.

Soon, the first seed will break the surface and cotyledons will unfurl. This is the time to add light, even if not all seeds are up yet. If you wait too long, this first one will get leggy and maybe even fall over. You can add light and it will not hurt the others since you closed off the top of the hole in the rock wool.

Adjust your light so that the first one stops growing taller by more than a small percentage. The job now is to force roots down, not stems up.

Once you have first leaves on all you can start to slowly bump the lights up a little a day. Wait until you have a strong root structure coming out of all the rock wool bottoms before transplanting. You may be doing a few each day as they might not grow at the same rate.

Thru all of this, you need to have a dry back period every day. Water from the bottom, not directly on the rock wool. This will encourage roots to grow to seek water.

There are no nutrients needed for the entire germination process.

As far as temps go, that has a big influence on growth rate and success. If you can put a seedling heat pad under and make sure they stay around 75* or so, it will all work easier for you. Too hot or too cold will give poor results.

Thank you!
Do you think I could transplant them into some seed started soil in solo cups to try to save them?

Moe.Red · Mar 25, 2021

BigBloomingBuds said:
Thank you!
Do you think I could transplant them into some seed started soil in solo cups to try to save them?

That one 2 over and 2 down that is bent over and creased in the stem - no saving that one I'm afraid. Even if you were somehow able to get it propped back up and feeding, it will likely be the runt of the litter and you would have been better off tossing it now.

What i would do at this point is to pull them all out, gently squeeze out the majority of the water, dry the tray off, and put them back in with only the water left in the wool. Try to prop them up with a stick to get the tops of the cotyledons and first leaves collecting light. Use whatever inert sticky thing you can, and maybe put a twist tie or something to make a loose ring around the steak and the stem to keep them there. I have an assorted menagerie of 3D printed steaks with rings for just this purpose.

Leave the dome off for a few hours and let them experience a dry back. Then only add a little water back in once a day just to wet their whistle.

You have some that will do OK there, they are straight and seem like fighters, but even then they are really droopy. The ones that are all bent up and curly - thats gonna depend on you giving them the perfect environment going forward as to how well they recover.

Mostlymooses · Mar 25, 2021

For some reason, a friend said rockwell does really well sitting on a thin layer of perlite? Maybe somebody else here can confirm/deny but he said that is the way to do it for rockwool cubes!

Rock wool and seedling tips?

Rock wool and seedling tips?

BigBloomingBuds

gorillaglueaaron

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BigBloomingBuds

gorillaglueaaron

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BigBloomingBuds

gorillaglueaaron

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Goodthingsgrow

BigBloomingBuds

Moe.Red

BigBloomingBuds

Moe.Red

Mostlymooses

Rock wool and seedling tips?

Rock wool and seedling tips?

BigBloomingBuds

gorillaglueaaron

🦍

BigBloomingBuds

gorillaglueaaron

🦍

BigBloomingBuds

gorillaglueaaron

🦍

Goodthingsgrow

BigBloomingBuds

Moe.Red

BigBloomingBuds

Moe.Red

Mostlymooses

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