How Dry For Rockwool Watering? Beyond The Simple Answer

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Juzam

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In a nutshell how dry before watering a top feed rockwool setup?

Simply put years of experience have shown clones specifically do best when they're on the drier side of the scale. Sloaked clones never root. General knowledge is that the closer you can get before reaching wilt point the better, for most mediums. Yet Grodan's suggestion is 40-50%, and we could be scientific and actually measure our Hugo's, yet that seems to still be more wet than we can go. Specifically, small plants that are not allowed to dry out do not tend to have heavy root growth out of the bottom and sides of the cube.

We're running tables and lifting each veg plant each day to weight it by hand. We'te starting to question wether or not we're actually watering them correctly. Experience has shown the drier we can get them the better root growth, yet manufacture says 50% weight... So what's been your experience and why?
 
J

Juzam

35
8
While in veg, yes. We haven't found any consistent other way, and if watered too frequently they do not seem to develop the same root growth through the sides and bottom.
 
P

Pimples

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Rockwool is much like coco coir ive found. I use slabs and blocks here and there in a top feed drain to wastw in the flower rooms. Often along side pots of coco coir. The 2 are very similar. You want the rockwool damn near bone dry but not a wilting plant and water till runoff again. This is in veg to establish a strong vigorous root system. I too water mostly by hand in my veg room every few days or so once in final slab (i like the uni slabs) or pot. You will know when your plants arw jamming and on that high metabolism stride when they drink that water and fertilizer down. A super light to lift slab or pot of wool. But not wilting. Its more of a feel thing. You just gotta get the knack for it. Once shes drinking to dry down daily or every other day I put them into tje flower rooms.About a 2 ft bush depending on strain. Here in the flower rooms you should have a very strong healthy plant with a FULL root system. Now you can fertigate when half or 50% of the rockwool thats fully wet to slight trickle of runoff from last feed. Remeber..50% dry down is key. With a slight trickle of waste run off. And only when youve established a vigorous root system in veg. You will get the hang of it. This is pretty much how you treat coco coir as well. Once you get into it you can get even more % of dry down to steer the plant into more of a flowering mode. Lower humidity and temps when flowers formnas well. And I know pro greenhouse veggie growers down by Lansing that fertigate this exact same way with long ass rows of rockwool slabs and tomatos as far as you can see. This is how its done son.
 
EventHorizan

EventHorizan

15,707
438
Rockwool is much like coco coir ive found. I use slabs and blocks here and there in a top feed drain to wastw in the flower rooms. Often along side pots of coco coir. The 2 are very similar. You want the rockwool damn near bone dry but not a wilting plant and water till runoff again. This is in veg to establish a strong vigorous root system. I too water mostly by hand in my veg room every few days or so once in final slab (i like the uni slabs) or pot. You will know when your plants arw jamming and on that high metabolism stride when they drink that water and fertilizer down. A super light to lift slab or pot of wool. But not wilting. Its more of a feel thing. You just gotta get the knack for it. Once shes drinking to dry down daily or every other day I put them into tje flower rooms.About a 2 ft bush depending on strain. Here in the flower rooms you should have a very strong healthy plant with a FULL root system. Now you can fertigate when half or 50% of the rockwool thats fully wet to slight trickle of runoff from last feed. Remeber..50% dry down is key. With a slight trickle of waste run off. And only when youve established a vigorous root system in veg. You will get the hang of it. This is pretty much how you treat coco coir as well. Once you get into it you can get even more % of dry down to steer the plant into more of a flowering mode. Lower humidity and temps when flowers formnas well. And I know pro greenhouse veggie growers down by Lansing that fertigate this exact same way with long ass rows of rockwool slabs and tomatos as far as you can see. This is how its done son.
you got some rw going now bro? Link me to your grow as I wouldnt mind following along.. I just grew a clone out in a 4x4 cube just as a experiment, right beside the coco plants DTW 3 feedings a day in flower..So i wouldnt mind following along if you have a thread...
 
P

Pimples

772
143
you got some rw going now bro? Link me to your grow as I wouldnt mind following along.. I just grew a clone out in a 4x4 cube just as a experiment, right beside the coco plants DTW 3 feedings a day in flower..So i wouldnt mind following along if you have a thread...
Man I would love to post pics of my grows. Been wanting to in these forums for awhile now. But all I got is this stupid Metro phone and I just dont wanna go through the trouble of figuring it all out. I can root a popsicle stick but with computers and phone tech savvy shit Iam a dumbass.
 
P

Pimples

772
143
You can even bust out the ole bathroom scales if you want to get real precise. I dont know how you would weigh it with a long ass meter long slab but with blocks..pots of wool cubes..or the unislab it wouldnt be hard. But anyways...weigh up a fully wet to runoff plant. Take note of the read. Then in a day or two..weigh the plant again. If its taking longer than a couple days to dry down..you should wait to water again and keep her in veg a little longer. Your roots arent vigorous and thriving and packed enough in the rockwool for 12- 12 yet. Run your veg room on the warmer and humid side and eventually she will start drinking that wool dry daily or every other day. And vigourous and thriving top growth. Keep your EC around 1.0 to 1.4. And pH right around the same as coco coir grown plants. About 5.6 to 6.0. Once shes jamming along in flower and drinking daily you can bump the feed to 1.4 to 1.6 EC. Slight trickle of runoff. About 10 or 15% of what you put up top should come out the bottom. Having it warm in veg and early flower helps to get her metabolism going too. But once buds develop...start thinking about lowering the canopy temps and humidity as well. And thats it. Simple. Rockwool is an awesome medium to grow in. Super simple. Much like coco coir but without the mess and hassle with pots of coco nor the whole cec and calcium/magnesium thing. Rockwool has no cec. Doesnt hold on to any minerals. And of course its much less time consuming when potting up with transplants. There isnt a transplant if you use blocks and slabs. Just stacking.
 
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cobman

cobman

6
3
I read most of these post and shake my head. I grow in rockwool mini cubes 5 gal pot. I top water return to 30 gal res. I water twice a day for 15 minutes at a time. cycles 50 gal through 4 pots. For a total flush.This is a auto water system auto return to res. They never dry out They don't need to there is so much 02 space between the mini cubes that they never look over watered. I have run this system for 5 years. I scrog a 25 square foot area with 25- 3590 cree at 700ma. Total of 900 watt at the wall. Won't go into PPf at this time. I average 3 to 4 pounds every 8 to 10 weeks. Rockwool is the easiest grow there is Ph stable no root rot,water temp not critical. Gnats not a problem with a little microbe lift. This is my first post here, but I ain't no rookie. I'm a great grandpa. KISS
 
EventHorizan

EventHorizan

15,707
438
I read most of these post and shake my head. I grow in rockwool mini cubes 5 gal pot. I top water return to 30 gal res. I water twice a day for 15 minutes at a time. cycles 50 gal through 4 pots. For a total flush.This is a auto water system auto return to res. They never dry out They don't need to there is so much 02 space between the mini cubes that they never look over watered. I have run this system for 5 years. I scrog a 25 square foot area with 25- 3590 cree at 700ma. Total of 900 watt at the wall. Won't go into PPf at this time. I average 3 to 4 pounds every 8 to 10 weeks. Rockwool is the easiest grow there is Ph stable no root rot,water temp not critical. Gnats not a problem with a little microbe lift. This is my first post here, but I ain't no rookie. I'm a great grandpa. KISS
Sounds good bro..
Welcome to the farm!
 
EventHorizan

EventHorizan

15,707
438
I read most of these post and shake my head. I grow in rockwool mini cubes 5 gal pot. I top water return to 30 gal res. I water twice a day for 15 minutes at a time. cycles 50 gal through 4 pots. For a total flush.This is a auto water system auto return to res. They never dry out They don't need to there is so much 02 space between the mini cubes that they never look over watered. I have run this system for 5 years. I scrog a 25 square foot area with 25- 3590 cree at 700ma. Total of 900 watt at the wall. Won't go into PPf at this time. I average 3 to 4 pounds every 8 to 10 weeks. Rockwool is the easiest grow there is Ph stable no root rot,water temp not critical. Gnats not a problem with a little microbe lift. This is my first post here, but I ain't no rookie. I'm a great grandpa. KISS
Post up some pics bro....u said 5x5 gets you 3-4 elbows huh... That sounds pretty good bro...
 
sixstring

sixstring

7,079
313
I post some in a day or two. I have a video on youtube look for cobman
said something about 1300 some odd watts,is it 900 or 1300 watts ? also said it was your first run under the leds,got any updates on that one video i saw?
lots of different ways to water/grow in rockwool that work great.welcome to the site
 
cobman

cobman

6
3
said something about 1300 some odd watts,is it 900 or 1300 watts ? also said it was your first run under the leds,got any updates on that one video i saw?
lots of different ways to water/grow in rockwool that work great.welcome to the site
It's capable of 1300 at the wall but I run it a 900 at the wall. That was first run under cob. I have run many under Mh ANd HS. I wil make another video in near future,
 
cobman

cobman

6
3
said something about 1300 some odd watts,is it 900 or 1300 watts ? also said it was your first run under the leds,got any updates on that one video i saw?
lots of different ways to water/grow in rockwool that work great.welcome to the site
It capable of 1350 if I run it all out but it to may par for that area. So I dial it back to 900 at the wall. Was my first run under cobs. I have run many under Mh and HS. Give me a little time to learn this forum.
 
P

Pimples

772
143
Basically I cant explain it any better than the latest vid by the HiGrow Group on Youtube. How to feed/water rockwool. This guy is a frikin pro and breaks it all down. And this is how you water and feed with precision. The way its supposed to be done. The way Grodon designed the substrate to be used. And how you dial it all in to use the full potential of rockwool.
 
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N

nicolajanjak

139
43
i used to think that it must lose 50% of his weight in water to feed again .. it seems wrong the good dry back is 25 %.
when you top feed and get a small drain under the cube you are at 75 % maximum saturation
in veg you want it to be at 50% wc to water again so the cube is still heavy
in bloom you can go down to 35 %, 40 % is a good number
 

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