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Rockwool v Soil

Long Beach, CA

Has anyone used Rockwool before for growing peppers? I acquired some cubes and thought I would try it this year to grow peppers. Any word of advice is truly welcome!
Thanks

Bay City, MI(Zone 6a)

Just remember its CEC is '0', so you'll need to fertilize with a fertilizer that has all nutrients essential to normal growth every time you water.

Al

Glenwood Springs, CO(Zone 5b)

Hmmmm....Anytime I have heard the term "Rockwool" used people were talking about asbestos. Obviously this can't be what you are talking about. What are you talking about?
:)

Sonny

Bay City, MI(Zone 6a)

Rockwool is used as a grow medium - made from basalt & chalk heated to liquid form at very high temperature and spun into fibers, like cotton candy. It's then cut into chunks or granulated. It can be formulated to be hydrophilic or hydrophobic (water-absorbing or water-repellent).

Al

Glenwood Springs, CO(Zone 5b)

Thanks Al

Sonny

So.App.Mtns., United States(Zone 5b)

I started a lot of seeds one year in rock wool cubes. Never again... but now it's been so long that I've forgotten what I didn't like about it!

Phoenix, AZ(Zone 9b)

What I don't like is that it does not break down. I have little cubes blowing around the yard now. When I dig up the bed, I still find the cubes, mostly intact.

Long Beach, CA

Thank you Al for the info on nutrition!

MaryMcP, you say they do not break down? How did they hold water? Have you had any root rot from them? Did they have good drainage?

Thanks

Phoenix, AZ(Zone 9b)

They seemed to hold water just fine. I just prefer sponge plugs. I use the BioDome system from Park Seed. That system has worked really well for me for at least 4 seed starting seasons. In hindsight, it may be that the rock wool plugs I found blowing around in the yard were an anomoly, doesn't make sense that they would not break down in the soil. I probably am not a good source for information since I have limited use. Sorry for the confusion.

Bay City, MI(Zone 6a)

It is a mineral product (rock heated until it's a liquid, then 'spun' like cotton candy), so it breaks down VERY slowly - so slow that for all intents & purposes it's inert.

Al

Phoenix, AZ(Zone 9b)

Thanks for the explanation!

Everett, WA(Zone 8a)

I wish that rock wool were manufactured as partially-sintered "stiff pretzles" of fine fibers. The unsintered parts would still hold water, but fairly stiff particles that are shaped like rods or tongue depressers would resist compaction better than spherical grains, limp fibers or blobss of wool.

Preferably helical pretzles with varying ptiches, so they couldn't nest tightly.

Corey

Long Beach, CA

MaryMcP, no worries. It all got cleared up in the end! Thanks!

Alexandria, IN(Zone 6a)

Rockwool was first produced in this country in my hometown about 1905 and was a booming industry for many years. At first they dug and quarried the limestone that was nearly on the surface at the west end of town.
Yes, it is nearly indestructible.

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