What's the Best Media (When You Got Burned Using Just Rockwool)

Hey All,

I used to grow a long time ago using Hydroton as my growing media and always had great results. For my first crop in years I was advised to use 6" rockwool cubes. I've got a moderately large set up, two ebb and flow tables adding up to 6' x 6', under two 600 w bulbs. For this first crop I had the 6" rockwool cubes just by themselves with no other media around them. The results were disasterous but no need to dwell on the past. I want to find a different media other than rockwool. I think it's OK for starting clones, and I have fifteen clones that are about ready to go that were started in 1" rockwool cubes but I still don't have a media picked out for the main grow.

The problem is size. I've got space for fifteen or more 2 gallon buckets in my ebb and flow trays and that would be a lot of Hydroton. I estimated the weight alone would be several hundred pounds of Hydroton, to which hundred of pounds more of water would flooded twice a day. Plus that much Hydroton is a heck of a lot of cleaning. I remember it being too much work years ago with a much smaller system. I really don't want to clean thirty gallons of Hydroton. What else can I use?

I already have my nutrients so I don't think I can switch to coco because I think that needs its own kind of nutrients.

I want something that is cheap, lightweight and preferably disposable. I've heard about growing using packing peanuts or perlite as a media. Has anybody here ever used them? My concern is that packing peanuts would be too light to support larger plants or that it may dry out too fast between flooding. I am considering using a mix of packing peanuts or perlite mixed with vermiculite and a small amount of Hydroton for weight and stability.

Am I on the right track or hopelessly lost? lol

Never had problems with rockwool. I switched from hydroton to rw because of the pain to clean them.

give coco a try, it gets better when re used, my coco webs up like a well blended organic soil. relatively light weight too.

you can try a "hempy" mix wich is 50% perlite 50% vermiculite. But you can do 50% perlite and 50% promix if you want.

Excuse me but what is promix?

I've thought about perlite but won't it tend to flow out of the containers when they're flooded? The buckets I'm going to use are just the standard plastic gardening buckets with drainage holes in the bottom.

I've also got some unused 6" rockwool cubes and may tear them up into small chunks to mix in with perlite or packing peanuts and vermiculate.

I already have my fertilizers and have been told that coca needs its own set of fertilizers. I spent a lot of money already on the first crop and get burned bad on it. I don't want to spent a lot more.

OK, I found promix at Home Depot. Wouldn't this mix tend to get all in the water and pumps in an ebb and flow system? This is a lot of what I'm looking for though. Thanks a lot.

Ive seen people put pantyhose around the bottom of the tops to keep the dirt in andact like a filter to keep it out of the works. Also id get a filter bag for your pump just cause theyre like 5 bucks and work well.

As for nutrients, i use dyna gro. Just 2 parts 1 grow and 1 bloom. Only mix in 1 at a time. 1 in veg and 1 in bloom. Pretty cheap. 2 a quart but its really concentrated so you need 5-10ml on average. Ive never gone over 12ml in mid to late flower and they are nice and green til the day we chop.

direstr8 said:

I already have my fertilizers and have been told that coca needs its own set of fertilizers.

Click to expand...

not true! although using coco specific nutes is your best option, it's not absolutely necessary. until i switched to h&g a&b for coco, i used pure blend, and a few supps. also gave a dose of epsom salt once a week. i got great results, and had no issues at all.

6x6x6 rw cubes are awful tall for a typical ebb/flow setup. Probably you needed a different size of rockwool. The local grow shop is stocking "growstones" which are remarkably lightweight chunks of recycled glass.

Pro-mix alone is not easily saturated from the bottom up. Cocogro is. I am currently testing a blend of the two for ebb/flow and the results thus far look promising.

Thanks! What makes you say that 6 inch tall cubes are too tall? It looks like the cubes will flood up till about the last inch of them. And that looks to be ok.

I've learned a lot from these posts and I think I have a solution. I'll post some pictures of it tomorrow.

Why such big pots? You can use smaller pots and not have nearly as much hydroton to clean (although no matter how much there is it's always a pain)

I have a lot of space so I opted for the two gallon sized buckets.

But really I think I'm limited by how many clones I can crank out at any one time. Right now I have 15 clones that are ready to go, all rooted in one inch rockwool cubes. Looking back, I could have possibly produced 20 or 25 clones at the same time. But I'm limited by the small size of my cloning area. Right now I'm working to create a much more space-effective way of producing clones so that in the future I can crank out 30 or 40 clones at one time. But that's for later.

Right now I have 15 clones all ready to go and a growing space that is 6' x 4'. So yeah, in a perfect world I would pick smaller sized buckets but if I've got the space right now, why not use it?

My decision right now is to use 6 inch rockwool cubes and to fill the rest of that small space up with packing peanuts, perlite and maybe vermiculite. I'll cover up each bucket with a plate that has a slit in it for the plant so that the roots are not exposed to any light.

direstr8 said:

Thanks! What makes you say that 6 inch tall cubes are too tall? It looks like the cubes will flood up till about the last inch of them. And that looks to be ok.

I've learned a lot from these posts and I think I have a solution. I'll post some pictures of it tomorrow.

Click to expand...

I typically lean towards smaller reservoirs, it takes a big reservoir to flood 5" depth. If you are flooding that deep, then I am puzzled as to why the rockwool didn't work. Are you using Pargro? I have had problems with Pargro and tend to stick with Grodan. How big a plant are you shooting for? A 6x6x6 should support a 3' plant with no problem if it is flooded twice per cycle. Slabs work great and can be cut into halves or thirds depending on how big you expect the plant to end up.

I'm puzzled why the rockwool didn't work. Lets just say this crop - my first in over fifteen years - was a disaster. I used to grow a lot starting about twenty years ago and every crop turned out fine. Back then I grew using two store-bought, pre-assembled set ups. So I learned a lot about the living plant but little about designing and cobbling together a setup myself.

My biggest mistake was I was over confident based on past successes but didn't see that I lacked an overall plan. I also got some really terrible advice from people and I made the mistake of believing them. , "

Another big problem seems to be one of communication between experienced growers and newbies. An experienced grower will toss around a term assuming that the listener knows what that term means, and a lot of the experienced people just don't take the time to explain what they mean. An experienced grower might say, "Grow in soil," all the while he knows the dozens of steps and hundreds of choices involved that he's perfected to an art form. No, he just tell the beginner to "grow in soil" so the new guy take a pile of dirt and sticks a plant in it.

In my case I knew from the past that I didn't like to clean that Hydroton stuff. Back when I used to grow it was called geolite but it's the same stuff. I knew I didn't like all of the work with it on a large scale so when the guy at the hydro store said "grow in rockwool" I took his advice. He didn't bother to tell me that the blocks of rockwool had to be covered up by something. Nope. I even asked him about this and he told me that I could put these 6" cubes right into my flooding tray. So the plants did fine at first but eventually I got a major leaf die off and the plants were severely stunted since then. No need to go into the other problems but they were many.

Now I believe that the main mistake was that I didn't have the rockwool enclosed, away from the light and in an environment that is humid but not flooded, and aerated but not dry. I should have known but this is what you get when you combine overconfidence with gullibility and when you get advice from some dude at the hydro store who doesn't give a shit as long as he makes a sale and doesn't have to be bothered. I didn't do my home work either. Though to be honest I've learned more from these forums and from videos on YouTube then from any of the popular books.

So...in brief I'm going to use 6" rockwool cubes in 2 gallon buckets. As filler between the cube and the bucket I'm using packing peaniuts and a mix of vermiculite and perlite, (1:3 ratio). I did a test set up of this and it looks fine. I line the bottom of the bucket with packing peanuts for drainage then set the 6" cube on top. I mixed the vermiculite and perlite together then wetted it so that it clumps a bit. As I'm jamming the packing peanuts down the sides I scoop some of the "hempy" mix in. In the little test I did some of the mix came out when it flooded but not as much as I thought.

To be honest I'm not sure I even need the "hempy" mix of vermiculite and perlite. I added that just so that it retains some moisture. The packing peanuts should pretty much do the job. They just have to protect the roots from the light and provide an airy and humid environment around the cubes. The plants will be growing in the rockwool, not the packing peanuts. I just want to make sure that the walls of the rockwool cube are not out in the open.

The advantage is that I don't have to deal with Hydroton again. It's a pain the neck to clean and it's heavy. The packing peanuts are cheap and disposable.

Any thoughts?

how is hydroton so hard to clean? You just put some in a pressure cooker for about 10 minutes and clean, then run it through a strainer real quick. Another alternative and the easiest is to just get yourself a net pot(size depends on you) and get neoprene collars and done. With the collars the roots will just dangle, but the neoprene collar holds the plane in place due to pressure.

Seems you have to clean all the dust off if it first. More work. I don't have a pressure cooker and don't feel like buying yet another gadget. Also they get crusty with salts from the nutrients. Like I said, I'm not growing in either packing peanuts or Hydroton. I decide to use rockwool but to have the small gaps filled in with packing peanuts. Time will tell. I may post some pictures in a new thread.

The only reason I can think of that your 6" rockwool cubes didn't work is that your solution was out of whack, either pH wise or PPM wise. What you are proposing will probably work OK, but I am not sure that the extra materials are needed. The biggest problems I've had with rockwool are:
1. incorrect nutrient solution
2. inadequate flood depth
At the moment, I am experimenting with a rockwool granulate/coco mix to see if the coco will wick up nutrient solution far beyond the flood depth.

I use 1/2 Coco 1/4 rockwool mini cubes and 1/4 perlite in normal 8in pots with and ebb and flow. It is very effective compared to the rockwool I used last time around. This combo is simple and uses the best qualities of the 3 mediums. Planyts love it.