Any Rockwool/Grodan Growers Here?

[FourOaks]

Hey all. Been forever since I posted anything here. Last year everything was doing well, I was the first grower with tomatoes at the market. Then the heat of the summer kicked in and once again my crops took a hit. I have been trying to retool my growbag situation, honing in a water schedule.

Meanwhile, I have also been looking into Grodan/Rockwool. Just curious if anyone here grows in it?

The advantages of Rockwool, it takes several days to dry out. The disadvantage is the price of the Rockwool itself.

Grodan, the largest producer of the Rockwool products has very limited info out there. I have spent the last several months, off and on, researching. I have Googled to my hearts content. I have Youtube'd, and did find an individual who has several short videos. I went to my local Hydroponic store, and asked questions. But Im coming up empty handed.

What got me looking into Rockwool, I took a tour of a very large commercial greenhouse last summer. They had huge greenhouses, utilizing just about every method of growing. Hydro, Raised Beds, In Ground, Grow Bags, but I was intrigued by the Rockwool.

The method that I saw, a transplant was in a small cube, 4x4x2, and that cube was on a slab. All was fed by drip irrigation. 3 Plants per slab.

Grodan offers a bunch of different options. Most I can buy at my local Hydro store, prices comparable, if not better then the internet. But, the cost for the medium would be around $5 for one plant, per season. I did see something about breaking up the cubes and slabs at the end of the year and using it as an additive to regular potting mix. In a sense recycling it.

So $5 per plant. And in my large tunnel, I would like to grow around 90 plants. You can probably start to see the cost issue. Not including Hydro fertilizer.

So, what im really asking, does the cost out weigh the benefits? Does rockwool allow the plants to produce more? If each plant would produce say 3 to 4 times the amount that I am used to, then I am all for it. Obviously commercial growers use it for a reason.

Anyone have any insight? This year, I plan to experiment some with the Rockwool, maybe grow a dozen plants or so.

[AKmark]

I can say this. I grow commercially in pro mix, a guy a mile up the road uses rockwool, both of us get great production. He uses his method I use mine, we both end up in about the same place. One thing is for sure, if he blew my production away I would switch, I can assume he would do the same. Maybe it comes down to what we are comfortable with.

[FourOaks]

Originally Posted by AKmark

I can say this. I grow commercially in pro mix, a guy a mile up the road uses rockwool, both of us get great production. He uses his method I use mine, we both end up in about the same place. One thing is for sure, if he blew my production away I would switch, I can assume he would do the same. Maybe it comes down to what we are comfortable with.

I appreciate the input AKmark. I assume that your operation compared to your neighbors is pretty similar then, aside from the rockwool/promix ?

My main issue is with my grow bags drying out. I know that a tomato can be grown in just about any size container, its a matter of moisture. I think, for those of us in the Southern part of the country, that we need a larger buffer. My research has concluded that the Rockwool will provide this buffer. Im on a well, so water can be precious.

I did run across a video that demonstrated a worse case scenario. A rockwool product was tested with a full size plant, to see how many days it could go, before drying out and causing damage. I believe the result was 4 days. Grant it, I don't have any environmental info. on the test.

[Cole_Robbie]

$5 per plant

That would fill about a ten gallon container with pro mix, at the price I pay, which is about $3.50 per cubic foot.

I'd rather have the pro mix. I think it gives you a chance of having more beneficial bio/fungal life at the root zone.

If you use rockwool, take a lot of precaution not to breathe the dust.

[AKmark]

Originally Posted by FourOaks

I appreciate the input AKmark. I assume that your operation compared to your neighbors is pretty similar then, aside from the rockwool/promix ?

My main issue is with my grow bags drying out. I know that a tomato can be grown in just about any size container, its a matter of moisture. I think, for those of us in the Southern part of the country, that we need a larger buffer. My research has concluded that the Rockwool will provide this buffer. Im on a well, so water can be precious.

I did run across a video that demonstrated a worse case scenario. A rockwool product was tested with a full size plant, to see how many days it could go, before drying out and causing damage. I believe the result was 4 days. Grant it, I don't have any environmental info. on the test.

We do have kinda similar setups. He grows more GH varieties, I tend to grow more heirlooms.
I often hear, or read, about folks fretting about containers drying out too fast. Here in AK we get 20 hours of daylight in mid summer, if it's 75-85 outside it is hot in the GH's, evaporation is real, and we embrace it. The more you can water the more you can feed your plants, then the faster they grow, yields increase too. If you can't keep up on watering it is indeed a serious concern though. I suggest a drip system on a timer, you can use inline injectors, or a tank system with ferts in them.
Good luck with your project

[FourOaks]

Originally Posted by Cole_Robbie

$5 per plant

That would fill about a ten gallon container with pro mix, at the price I pay, which is about $3.50 per cubic foot.

I'd rather have the pro mix. I think it gives you a chance of having more beneficial bio/fungal life at the root zone.

If you use rockwool, take a lot of precaution not to breathe the dust.

Ive probably inhaled enough perlite to fill a 5 gallon bucket.

Originally Posted by AKmark

We do have kinda similar setups. He grows more GH varieties, I tend to grow more heirlooms.
I often hear, or read, about folks fretting about containers drying out too fast. Here in AK we get 20 hours of daylight in mid summer, if it's 75-85 outside it is hot in the GH's, evaporation is real, and we embrace it. The more you can water the more you can feed your plants, then the faster they grow, yields increase too. If you can't keep up on watering it is indeed a serious concern though. I suggest a drip system on a timer, you can use inline injectors, or a tank system with ferts in them.
Good luck with your project

Oh believe me, I embrace drip irrigation and timers. One huge issue, Im on a shallow well. I do have a 5000 gallon backup tank. I also have my eye on a 350 gallon tank to mix fertilizer in.

I do have plans this year to use the 5 and 7 gallon grow bags again. I think im going to mulch the tops of the bags to help with evaporation, and up my drippers to 2 gph from the 1 gph.

Im still considering growing a few plants in Rockwool. Im really curious about it. I just wish that Grodan would put some info out there that is useful. They have 2 websites, and I was able to extract more info. from Youtube, from 1 user of the product. For example, they tell you that block x is good for "small plants" and block y is good for "huge plants". Well... thats about useless.

[PureHarvest]

Four oaks, it just doesn't sound like you were running your current system long enough each day.
Even if you were, you can't overcome heat indexes over 100 with water management alone.
30 percent share cloth over you area would help. I forget if you are under a tunnel or not.
I really don't think media is your issue. Bag culture isn't really supposed to be like soil in that it is not a store for water that is need for more than one day's use.
You should be able to apply one day worth of the crop's need per day (assuming your well can supply that).
Even earthbox users fill the reservoir daily on full plants in high temps. Basically, bag culture is maybe not ideal if your well supply is a big issue.
I would guess that 1 gph emmiters in your climate should mean that you needed to run you pump for about an hour total per day. Probably 20 mins at sun up, 20 at noon, 20 at 4 pm. Maybe even longer if I had time to do the math on my 3.6 gph in similar climate.

[Nightshade]

Here in the desert, I have begun to mix coco coir into commercial peat based planting mixes which dry out quickly. It seems to hold moisture better than vermiculite, and (I have been told) grows more acid over time, which helps to counteract our alkaline water. jan

[FourOaks]

Originally Posted by PureHarvest

Four oaks, it just doesn't sound like you were running your current system long enough each day.
Even if you were, you can't overcome heat indexes over 100 with water management alone.
30 percent share cloth over you area would help. I forget if you are under a tunnel or not.
I really don't think media is your issue. Bag culture isn't really supposed to be like soil in that it is not a store for water that is need for more than one day's use.
You should be able to apply one day worth of the crop's need per day (assuming your well can supply that).
Even earthbox users fill the reservoir daily on full plants in high temps. Basically, bag culture is maybe not ideal if your well supply is a big issue.
I would guess that 1 gph emmiters in your climate should mean that you needed to run you pump for about an hour total per day. Probably 20 mins at sun up, 20 at noon, 20 at 4 pm. Maybe even longer if I had time to do the math on my 3.6 gph in similar climate.

Yep, been looking into shade cloth to go over the tunnel. Aside from that, I dont recall for sure, but I think I ran 30-45 min, 3 times a day. That seems about right.

The last 2 years, the exact same thing happens. All is well until late June, when the heat ratchets up a few notches. So my thoughts are to mulch the bags and upgrade the drippers.

[FourOaks]

Originally Posted by Nightshade

Here in the desert, I have begun to mix coco coir into commercial peat based planting mixes which dry out quickly. It seems to hold moisture better than vermiculite, and (I have been told) grows more acid over time, which helps to counteract our alkaline water. jan

I was at my local Hydro Store earlier today and was looking at the Coir products. I was wondering if the water holding capacity was any better.

[FourOaks]

Now that I am really thinking about this problem, I wonder if I wouldnt be better off to add something like a saucer to catch excess, so it can reabsorb until the next water cycle.

I think if I did that, I would add extra drainage holes.

[Cole_Robbie]

Sure. I set container plants in a shallow bin of water in very hot weather.

[kurt]

Some insight from the past.
I started using Wonder Soil when acclum out in California posted it here.The wonder soil has a wetting agent in it.
Then the topic came up about rockwool.
Grodan and all the cannabis crowd love it.
They make a killing from the turn around time.
The stuff is spun,blown non organic and WILL NOT BREAK DOWN.
The European growers are already starting the narrative on what to do with the waste disaster it is causing arising from thier limited dumping grounds.Our local hydro shop is carrying coir from the Netherlands(processed from India)in bales.He dumped the Fafards,Pro Mixes as a go to commodity mix.I use the coir and dump perlite(a lot) and those roots glide through the coir(which absorbs liquid ferts like sponge)and releases evenly.No more sticks,Canadian pro mix hornworms,wet sludge in my 10B,humidity laden garden.In the archives there was a mention of rice/chocolate cocoa husks.I got some 50 lb bags of each and am in process of monitoring growths.Will keep updates when possible.




http://www.tomatoville.com/search.php?searchid=2539874

[PureHarvest]

The other thought I forgot to mention is your production schedule.
Perhaps you should be doing two crops: an early and late.
Then you would avoid trying to ripen fruit during July and August. That is what I am doing this year to avoid the 4-8 week stretch that leads to the stress and splitting.
I just got back from Agweek conferences here. Lots on tunnels and tomatoes.
A researcher used 30% shade cloth in the field and on a tunnel and reduced yellow shoulders and splits significantly. He said high root zone temps mess with the plant's ability to uptake potassium, which is needed greatly from flower through harvest. So a combo of shade cloth and white plastic instead of black accomplished root zone and canopy temperatures that were lower than the control. Fruit production did not increase, but marketable fruit was much greater. Yellow shoulders and white core is due to K not getting into the plant.
Another guy was talking about Magnesium. Most growers (me included) use Magnesium Sulfate in our solution. He says it takes 4-6 weeks to get into the plant even in a liquid feed system. He uses a chelated mag that gets in around 2-4 DAYS.
He also spent a lot of time urging to tissue test. Mentioned it about 10 times. You could be applying tons of calcium etc, but is it getting into the plant? Start 4 weeks after transplanting (flowers are not out yet but the embryonic cells are already formed inside the stem, and then every two weeks to see where you are. He goes high K at this stage (week 4 after transplant).
Targets from tissue test:
N 3.5-4%
P .8-1%
K 3-4%
Ca 3%
Mg .8-1%
S 1.2%
B 50 ppm, Zn 50 ppm, Mn 100 ppm, Fe 100-300 ppm, Cu 20 ppm
He also mention using a root drench product at transplant as standard procedure (actinovate, rootshield), using automated ventilation for roll up sides/end vents, adding silicon to he mix once per week (lots of stuff like that Aptus line of products, Mark. Just not catering to pot growers and actually have guys out in the field to make recs/give guidance on how to build a tailored program).
Says he can get two seasons out of potting mix with tomatoes. Just rip the plant out of the bag/container, top off with new soil, and transplant into bag again. Says another reason to do root drench as SOP.

[Ricky Shaw]

Good water-soluble and dry fertilizers contain chelate agents, check ingredients for EDTA or DTPA associated with copper, zinc, or iron. The grower could be referring to just using epsom salts off the shelf, in isolation from other ingredients.