Germinating in Rock Wool

I've found it easier to germinate in the paper towel method.
once sprouted it goes into a 6x6x6 rockwool block for the rest of its life. DTW.

The only time I ever experienced damping off was when I tried rockwool.........I'll pass.

I use rockwool for seeds and root riot plugs for clones.

So far, I have nearly 100% success with seeds and after switching to peat plugs, I have 80% success with clones.

marleygdope said:

AUTOFLOWER

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donkey boner

marleygdope said:

AUTOFLOWER

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Tulip

please dont squeeze, its not a flexible substrate like a soft sponge... or shake it, make a mess and more work for yourself.
The small plugs by themselves tend to hold water too well for me so after a ph soaking and drain I fold up a dry clean towel, paper or whatever, and set the base of the plug on it until I hit the level of wet I want. The liquid gets sucked out pretty quickly. Makes it simple to correct overwatering.

Hobbes said:

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I've never germinated in Rock Wool, don't know the difficulties or tricks of the trade.

A book I'm reading, "Three A Light", suggests using the paper towel method, which I'm familiar with, then transplanting to rock wool. This seems like an extra step, why not plant the seed in the rock wool and save the risk of damaging the sprout.

Anyone use rock wool for germinating? Tips of the trade would be appreciated.

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Rockwool is the way to go. Paper towels can drown the seeds if you are not careful. Plus moving them to another media has its own risks. I DO use paper towels to test viability of seeds that I have made but after I get my results I just throw the seeds away. Before you use Rockwool it MUST BE pretreated. The reason for this is that some of the materials used to make it (basically rocks!) contain large amounts of lime which has a high calcium content. This lime slowly dissolves raising the pH. When I first started growing I had the hardest time keeping the pH at an ideal 5.5 until I heard about pre-treating. Pre-treating is is done as follows:

• Before you do anything put on a pair of rubber gloves to limit contamination. Washing your hands first is also an option.
• In 1 gallon of clean water add GH pH down drop-by-drop until the pH reads 5.5. You should use a pH meter for this but pH test strips or drops from Amazon or wherever can give fairly accurate results. A good estimate is to use 1 gram of GH pH down per gallon.
• Drop the starter cubes into the solution of water and pH down and let soak for several hours or even overnight. This pulls the calcium out of the cube.
• After soaking dump out all of this water and add fresh water to the cubes to rinse out the acid solution.
• Then add a 1/3 strength fertilizer solution at a pH of 5.5 to the cubes.

When I use this method of pretreating and place the cubes in a germination tray with a heating mat I get near 100% germination. I also built a germination chamber with a temperature control to keep the cubes at about 77 F Rockwool is sterile so a condition called “damping off” (seeds attacked by molds) is greatly reduced. Rockwool is simply the best because it is sterile.

lusidghost said:

Who is having issues with Root Riot plugs? The only germination issue I ever see is from people putting the seeds in a paper towel.

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I have been using the paper towel method for 20+ years. After reading how much better plugs are supposed to be, I tried them. Nope, the paper towel method is better, YMMV.

speedwell68 said:

I have been using the paper towel method for 20+ years. After reading how much better plugs are supposed to be, I tried them. Nope, the paper towel method is better, YMMV.

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I don't believe you've been growing for 20+ years, but fair enough. What exactly did you dislike about them?

I first started growing in 2001, with some seeds I bought in Amsterdam from Sensi Seeds, the were Shiva Shani II. I kept that strain going for a few years. I stopped in 2015, because the Police turned up when I had a load of plants out in my conservatory and I was taking clones. That was a close call. I started again in 2020, when the pandemic started.

I had a seed that seemed to have turned in the plug and fucked up. If I was using the towel method they would have just been put straight in small pots of seed mix. IMHO they have removed that extra level of control, again YMMV.

Plus, the plugs cost £9.99 for 50, paper towel costs £0.001 per sheet. I am going to start taking clones again, seeds are just too much of a "crap shoot" and I think that the plugs will be excellent for that.