Propagation: Starting seeds in rockwool cubes

Chariton, IA(Zone 5b)

This is a first for me. I've grown cuttings with some luck in Rockwool before, but my luck with seeds in the cubes has exceeded my wildest expectations. To begin with, I've kept the seeds/cubes covered with that new sticky plastic wrap. I lift a corner quite often to peek in. Sorry, it's a problem I have, I just have to watch the progress. These were planted about a week to ten days ago and there are several crosses in this mix. This started out to be a test just to see if it would work. I think I know how I'm going to grow my seeds from now on. I'll let these stay in this container until I can see roots coming from the bottom of the cubes and then I'll transplant into my next size up pots.

Thumbnail by Brugie
Westbrook, ME(Zone 5a)

Good idea Brugie! I have some of these cubes I bought for cuttings. Nver thought about trying them for seeds. Did you peel your seeds first?

Chariton, IA(Zone 5b)

Sue, some are peeled and some aren't. However, the peeled ones are coming up first.

Cicero, NY(Zone 5a)

Where'd ya get the cubes?

Chariton, IA(Zone 5b)

Darn, I knew someone would ask. I know they can be purchased cheaper, but I got mine at

Forgot to say that the next time I order, I'll get smaller ones. I believe it was Mary that had a link someplace with a good deal on them. Maybe she will come by and see this and help out.

This message was edited Dec 19, 2003 6:53 PM

Harrisville, MI(Zone 5b)

Girl,You have seeds up already!I gotta get some dirt under my nails!They look great!

Marshfield, MO(Zone 6a)

This is where I got mine, they were 1 x 1 x 1.5. I like the individually wrapped ones like you have, though.

Chariton, IA(Zone 5b)

Thanks Mary. Have you had good luck growing brug seeds in the cubes? It sure is a clean way to grow stuff.

Tellico Plains, TN(Zone 7b)

Mary , same place I got mine. Gonna give it a try after all the Holiday stuff is over. Do you think the rock wool soak they sell is necessary?

Chariton, IA(Zone 5b)

Shirley, I sure didn't use it. What is it supposed to do anyway? I didn't even look into it to see.

Tellico Plains, TN(Zone 7b)

some kind of nutrition from what I gather

New from Supernatural. Use this product to prepare rockwool for planting. It corrects the pH and adds the proper amount of nutrients all in one application. AMMONIA FREE! 100% ammonia free nitrogen is finally here, no more burning your plants with ammonia build up. Use 1 teaspoon per gallon of water, soak or drench the rockwool, allow it to drain then plant! It really is that simple, and it really helps the plants get off to a good start.

This message was edited Dec 19, 2003 9:54 PM

Chariton, IA(Zone 5b)

I'll just give mine some fertilizer when they get a couple of leaves. Cuttings live in water, so I think the babies will be okay.

Marshfield, MO(Zone 6a)

I don't think it is necessary for seed starting, I think it is more for planting stuff that is already growing because it has fertilizer in it.

Yep, I have had good success with the rockwool. I posted the pics at BGI, remember, of the Rosamond x Rothkirch seedlings. Well, long story short, those seedlings bit the dust because I let them dry out, wasn't the rockwool's fault, it was mine. I could kick myself. But I have since started several batches of seedlings with good success. I even had some Knightii x L'amour seeds in soil for quite a while, nothing happened, I dug them up, only one was viable, put it in rockwool and it sprouted almost immediately. I have some Rosamond x Pink Pearl in rockwool now that is sprouting, and I also have Enchanted Double White x Rothkirch planted, has been planted for quite a while, but no germination yet, I am keeping my fingers crossed, maybe these are just real slow to germinate.

Tellico Plains, TN(Zone 7b)

Can you consider the rock wool a sterile medium?

Chariton, IA(Zone 5b)

Sounds like some nice crosses. I'm so anxious for spring to get here. This is going to be a great brug year, I can tell.

Denver, CO(Zone 5b)

Brugie, I also got mine at bghydro. I didnt peel mine, nothing has come up yet, but nothing is rotted either. Im tempted to peel some, and try it from there! Thanks for sharing this! They're looking great!

When you get ready to transplant your seedlings or cuttings into a larger pot-do you plant the rockwool cube with the seedling still inside of it? Just cover whole cube with potting soil? That would be great to do that no transplant shock-right?

Marshfield, MO(Zone 6a)

You'll find step by step info here

Newnan, GA(Zone 8a)

got my rockwool on the way and am ready to take off, this is sounding so good.

Mary,thank you so much for the information.

GOD's Green Earth, United States(Zone 8b)

I can't wait to try this with all my seeds! Thanks for the post Shirley! And Mary, thank you for the instructional link -- thats very well done.

Lee's Summit, MO(Zone 6a)

Friends, I have used the rock wool cubes for quite awhile to root cuttings and start seeds - try 'wicking' the cubes - put the cotton string into the center cube (don't plant in that cube), and as long as the cubes are still intact, in a sheet as they come, and the reservoir that the string is placed in stays full, the cubes will self-water. After they sprout/root, you can also fertilize this way. I can grow most things with this method, but I do one more thing - I make a greenhouse dome to keep the humidity and heat constant, which definently helps.

Columbia, SC(Zone 8a)

Got to give this a try.

Northern California, CA(Zone 9b)

OK, I ordered!!! Thanks Kay for your input also!

Chariton, IA(Zone 5b)

Capillary matting works well too. I have some trays that don't drain. I put some sections of PVC pipe in the bottom of the tray (legs)to hold a piece of plastic grating that is a little smaller than the tray, off the bottom about an inch and a half. Over the grating, I place a sheet of capillary matting with tails that will hang to the bottom of the tray to wick up the water. This works great. I don't have it set up for seedling trays yet this year. The grating is just a section of the stuff that is used under the four foot ceiling lights in a dropped ceiling and can be purchased at a Lowes or HD. Then it is cut to size.

Marshfield, MO(Zone 6a)

We used to do that with african violets, we set the pots on top of the grating, same stuff you talked about, plastic that goes over fluorescent light ceilings. The would run the wicks from the pots of the violets through the grating into trays of fertilized water below. It worked great.

Chariton, IA(Zone 5b)

I'm glad you could figure out what I was talking about. I've found that the only draw back to it is the fungus gnats that are attracted to the water, but they are attracted to my humidifier too and seem to drown easily. LOL At least better than having them flying around or laying more eggs. The population is very small now.

Herbstein, Germany(Zone 5a)

I use glasswool, used in Aquarium filters, with excellent results. I found a source for Rockwool in Germany but I have to buy a too large amount of it.Maybe my favorite gardener will share it 50/50 with me.

Denver, CO(Zone 5b)

Monika, maybe you could just let us send you some. I think Kell has offered, and I sure wouldnt mind getting some in the mail for you. Just a thought.
I have found a couple sprouting in my rockwool also. Its amazing how fast its happening.

Chariton, IA(Zone 5b)

Shelly, did you get the cubes or the slab? I think either would work well and the slabs are much cheaper if I remember right. When they are wet, it is easy to poke a hole in the material big enough for a seed.

Denver, CO(Zone 5b)

I got the slab. Its so easy to cut them apart with a knife. It was quite cheap, and gosh they are so light when they arent wet. The slabs that I got already had the holes and. I think Squirt thinks I did a good thing by getting the rockwool. (I have to let him think he has a say in what I do)

Thumbnail by Shelly221
Lima, OH(Zone 5a)

Awww... mom's little helper.

Denver, CO(Zone 5b)

lol he sure is. He loves Monika's book! I cant leave it on the couch after reading it, he lays on it, and when I go to move it, he growls.

Thumbnail by Shelly221
Chariton, IA(Zone 5b)

The slabs I bought are probably 2 inches or more deep and six inches long and about three foot long. They don't have pre-drilled holes in them. I have no idea why I bought them, just thought it was something I should have. LOL!!

Denver, CO(Zone 5b)

LOL I do that ALOT Brugie. :o)

Marshfield, MO(Zone 6a)

The slabs I have look like Shelly's, they have holes.

Chariton, IA(Zone 5b)

I think what I bought are for continuing to grow in rockwool as in hydroponics, but I figured I could make use of the stuff anyway. I'm a person who loves a challenge and now the challenge is to figure out how to use this stuff.

Houston, TX(Zone 9a)

Brugie, I am definitely goint to try this. Thanks for letting us know about your experience. I think all of us have to try different things and see what works best for us in our individual areas. Thanks, Frannie

Yukon, OK(Zone 7b)

Brugie, this is a great thread. One question I saw asked and can't find an answer for it. After your seedlings are up and strong, will you just transplant the cube? That sounds like an easy solution if it will work.

Brinda :)

Yukon, OK(Zone 7b)

LOL....don't answer that! I've read everything and have the answer now! Have a great day!

Brin :)

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