Rockwool, fertilizer salt accumulation; truth or myth?

I often hear that Rockwool growing media should only be used for annual crop growing since it has a tendency to accumulate fertilizer salts which may kill plants if they are grown in it for longer periods of time. Truth or myth?
I personally have grown tropicals in Rockwool for about 2 Years and have not seen this problem but I'm worried that they may die suddenly if I don't re-pot them into another medium.

Panama.........what tropicals are you growing with hydropontic, sounds like you're having success with it.

"eyes"

Hmmm, let me see.
Heliconia psittacorum, some Pepperomias, Hoya carnosa 'variegata', Euphorbia submammillaris and several Cacti and succulents. Besides tropicals I had used it with great success on tomatoes and peppers.

Wonder how it would do with gingers and hibiscus?? Difinitely gonna get on the tomatoes and peppers for DH.

"eyes"

A good forum and looking forward to "watch it grow" so to speak. Have been playing with hydroponics for over 10 years and find it extremely rewarding for some reason. Eyes ,it is more a question of what you cant grow .Panama , have used "rockwool" and yes ,found it to have a use by date but there is not reason why it cant be flushed when required.It worked for me.I have found this a good practice for all mediums including NFT. John in OZ.

what other mediums have you used?

Sand,perlite, vermiculite,sawdust,polystyrene balls,scoria ? (volcanic rock), gravel, peat ,cocoa fibre and mixtures of the above. Dont think I missed any :-)
John in OZ

John, what is said about Rockwool is that the fertilizer salts do not get washed out with flushing and this is being blamed for SPDS (sudden plant death syndrom :).
Another theory is that potassium, used as a lubricant in the spinning process of the fibers, is leaching over time from the medium causing an overdose.

Mediums used on my side to this date are: Rockwool, clay pellets, perlite, vermiculite, coconut husk chips, bark, lava rock, foam (propagation) and ceramic grains.
Systems used: "Ebb-and-flow", drip and capillary systems.
Haven't tried NFT systems yet, but worked on the tools making the channels including covers for it at work LOL.

BTW John, you lucky folks down-under can get Hoyas way easier (and most likely cheaper) than here. Wish I would life there :), actually I'm still waiting for an Job offer to go there.

Milan

holty, I want to pick your brain. I've been interested in Hydro for years, and did grow some lettace in a home made ebb-and-flow system. Do you use homemade or purchased units? What is your favorite method? I'd like to try an aeroponic system, are they everything they claim to be? Thanks in advance for any info!

Skye

Skye,I was going to say The sky is the limit but, I will anyway. With hydo there really is no limit to what I has seen people use ,me included.Depends on your situation,location,"handyperson" ability and what you intent to grow. Lettuce , NFT wins hands down and some varieties are better than others for this. I have used old poly boxes painted with a "terracotta paint with sand added" to fool people .It did. Downpipe ,guttering ,roofing iron ,we call it "clip lock" here :____:____:____:____: looks like this and is great for "flood and drain" type hydro.You can stand 8" pots in the gullies and flood them.
I will try and dig out some pics and post.
John in OZ.

Hey, pics would be great! I think I'm about to get more handy, 'cause I'm tired of waiting for DH to give me a hand. He bought all the stuff to make me an aero-hybred unit for my birthday last year, but it never got further than that.

Panama was the rock wool being used in hydroponics or soil? Some people use it to germinate for soil use. Some hydro growers will only use rock wool. You can have a little problem with the Ph & EC if it is used. I prefer to use gro-rock, it is more economical to use and more control over the PH and EC. Gro-rock can be re-used over and over again.
http://www.simplyhydro.com/growing3.htm Pros & Cons of Rockwool

Cindy

This message was edited Jan 7, 2004 5:59 AM

I have found a place in Dave's Garden where I can really participate with my hydro/aero and bioponic experiences. I have never used any store bought systems, they are too easy to make and most hydro stores sell all the hard to find pieces if you can't find them. My favorite system to date is a drip system I made using hydroponic ferts..
I'll describe it quickly and can find a bunch of pics/instructions for making other hydro/aero units.
The easiest and most fool proof hydro system is a knock off of General Hydroponic's "emily's garden". It is nothing more than netted pots sitting submerged in hydro solution and a airstone to keep the O2 levels up. http://www.greencirclehydroponics.com/hydro.htm I was going to do a write up on this until I found the website of my local hydro store. The link above contains pictures and great descriptions you can use to make your own for a fraction of the costs. Like holty said, "the sky is the limit" and there are SEVERAL WAYS to get great results. Don't let anyone tell you different. I've seen rookies with simple systems outgrow others with hi$ systems. I think its just a matter of finding a unit that your comfortable with and run with it.
My best performing system to date is a drip system. Most everyone will tell you that you can't keep nutrients running 24/7 or you will over do it or get root rot. That's simply not true if you have adequate O2. I had tubs that are 4'x4'x 6inches deep. I'd fill these tubs w/ around 12 plants full of grorocks(lava rock like pebbles). I would run 1 drip line to each pot constantly running at a rate of 2 gallons per hour per plant. The bottom of each tub was fitted w/ a drain line the recirculated the nutrients back into a res. of nutrients. The res. is just a rubbermade 35 gallon tote containor. I used a small powerhead style aquarium water pump connected to a 1/2inch tube that ran to the tubs. Then I'd connect 1 drip line per plant onto my 1/2 inch "main nutrient line or tube". The only crucial part of this operation is monitoring the PH level of your nutrients and to make sure the res. is topped off w/ fresh water every few days. I always changed my nutrient evey 2 weeks. Pour it down the drain and mix up a new batch in the res.. Around and around you go until your plants are where you want them or your crop is finished at harvest time. You can make all this hydro stuff as easy or as complicated as you wish, KISS: keep it simple stupid turned out to be the best idea yet.
I highly recomend starting off w/ the Emily's Garden from home made parts. Instead of buying the unit at the above link, go to Home depot or Lowes and buy all the parts there.
PARTS LIST:
1 shallow container around 8-10 inches deep
6 or more 1 quart netted baskets depending on lid size.
1 small air pump from pet store
1 6 foot long piece of air tubing
1 air stone
1 bag of growrock or other growing media
1 utility knife for cutting holes in lid.
1 small drill and bit for air tube hole
1 hydroponic nutrient (they vary a lot)General Hydroponics brand is easy for the beginner.
1 PH tester. A cheap 1 from pet store will work great.

You can start off w/ a simple shallow storage container(Ideally 8 inches or close). Look at the dimensions of Emily's garden and the plant spacing per netted pot. Then take the lid to your container and measure it out. Try to keep the sites for your pots around 4 inches apart. You'll need to locate a gardening center or hydroponics store to find the netted pots/baskets. The size and shape of your baskets determine the spacing and size of holes to be cut in the lid of your container. Some netted pots are square and some a round. You want pots that could carry roughly 1 quart. I found 6' round baskets here so I cut my holes 5' in diameter. This smaller hole kept the baskets off the bottom of the container barely, you want the nutrient to be able to surround the pots all the way around and under. Thats the only hard part. After measuring out where the holes go in the lid, I used a utility knife to cut through the plastic lid. Now you need to drill a small hole in the side of the container just below where the lid fits on. This is for the air pump line to enter the container and connect an airstone to the tubing inside the container.
Now fill you container /res w/ water 1 gallon at a time to see how much nutrient you'll need to premix before pouring into the container. Then place netted pots filled w/ growrocks in the holes in container lid. Plug in the air pump and then you can begin potting plants in your baskets. I would buy a book on this subject or check out the library to see what kind of plants do well. The nutrients bottles have different strengths of nutrient for different plants so you'll find a small list there. Its trial and error, I think you can grow anything in there.
PHEW! I hope I did ok in describing this. I'm worn out now. Try searching the net, you'll find more links than you could read. Many other DIY systems too along with nutrients etc., on and on.
Feel free to ask Q's and I'll do my best to keep up. I'm SURE holty could answer all of these questions too. He knows what he's talking about since he is building a trough system. That's 1 more of the hundred's of ways to do it right IMO. It's all personal prefference and what you feel comfy with.
JD

Thanks for all the info. I hope to try some when I get my own place this summer. Haven't checked out the link yet... but WILL!

Rockwool is a slow drainer, so that might be the issue stake. I always had great experiences with it, but I never tried to grow anything in it that was under lights for more than a couple months or so.

I always preffered the grow rocks over RW. I've seen those slabs teaming with larvae for fungus gnats and the like, YUCKO! I know seveal others that have had great luck like you Buck.
So just what kinda plants were you growing in there with roughly a 60 day flowering period brother;)
I miss my hydro room, hopefully I'll have the chance/time to fire it up again someday before long. I miss my sunroom and my lovely ladies flowering away. I ended up getting darn spidermites and other troubles so I shut it down. Using Avid, I could keep the mites managable but I could never get rid of them totally. I even tore it down, washed it floor to cieling with a bleach solution, fogged it a couple times and sterilized everything the best I could. They always found a way back in there, I think they linger in the air just waiting for the right conditions and then screw up everything. Oh well, tis life.
JD

JDL , i know what ya mean on the mites .. GRRrrrrrrrr ... Ive even tried dressing up as
a nija and pop into the room , no luck , they just came back with a vengence .. LOL ..
next time Im getting some other bugs to eat them ,, just have 5000 lady bugs running
through the house . heheheee e ...

I have home brewed all my hydro gear and even did hydro outside .
theres a thread here with a pic of my pepper plants .

I just use the rockwool cubes to germ seeds in then transplant to a pot with growrocks.

The last run i did in the house was hydro strawberries, aeroflow system and just
used neoprene collers to hold the plants in the holes so the crowns stayed dry ..
and a few peppermint plants ...

they all were doing great , picking a few snack berries every few day.
then the mites came back ..

when i tore the system down the peppermint roots were pure white and had
a nice bright green stripe down the main root line which i never seen before
and looked really neet .. ( i should have took a photo of them )

That sounds very cool, I may have to set mine up again to play over winter. It sure is a bunch of fun once everything is all set up and dialed in. Getting to that point is brutal.
I've tried so many different methods of nute delivery and I had my best luck running a drip system that ran 24/7 delivering 2 gallons per hour per plant. I used oasis cubes in the same way you use RW. Cubes make handling seedlings and cuttings so much easier and healthier IMO as they aren't nearly as fragile as bare rooted stems.
I used 2 4x4 foot tables with the plants sitting in them in individual pots and the nute was recycled by draining into the tables and back to the res. located just outside the growroom. I kept my res. located just outside the room to keep the temps down. I ran a 1000watt MH over each table and when it was time to initiate flowering, I switched over to High pressure sodium lighting via conversion bulbs. In flower I used a 14 hour on and 12 hour off lighting schedule. When growing the plants up to size, I ran a 18 hour on and hour off schedule. I sure miss playing Ma Nature in my micro climate. I used to work in there for hours on end under the lamps during winter. It kept the winter blah's away well via home made sunshine therapy. Once the mites wouldn't go away and summer came back around, I shut it down and just never got back to it. It makes me ill having all of that equipment just sitting collecting dust. LOL I wished I would of had my digital camera back then as I haven't a single picture of my set up. Oh well, maybe another day;)