how often to water rockwool (grodan)

[keepleft]

hi how often and for how long to water rockwool? i used to do it 15mins every 4 hours when lights on. but i got root rot (pythium) too wet.

 

now i got digital timers. doing it 1 min every 3 hrs in vegetative stage, and 2 min every 3 hrs in flower.

 

not using drippers. water coming out of 4mm hoses. in 1 min they get about 3lts of water. 200lt reservoirs.

 

thanks all

[Guest Eikel]

More info please mate, what size slab are you using?

 

How many plants per slab?

 

Slabs run in channels with covering or another method?

 

3ltrs seems alot, but without any indication of how big your rockwool is and how you have it set up it's a bit hard to give you a meaningful answer.

[Tom]

now i got digital timers. doing it 1 min every 3 hrs in vegetative stage, and 2 min every 3 hrs in flower.

 

not using drippers. water coming out of 4mm hoses. in 1 min they get about 3lts of water. 200lt reservoirs.

There are also other variables to consider, i.e. a young plant with only 2 or 3 nodes is not going to need as much as one that is ready to flower. The best indicators are the plants themselves, if they are happy and growing well then you are doing it right.

 

[keepleft]

hi guys

 

the system i am using is the tried and tested 'crop box'. see picture of what the system looks like (although that is not mine exactly). I have a 200 lt reservoir connected to six of them

 

the size of the grodan is the standard size 'slab' cut in half to fit the box.

 

there are 2 plants per slab.

 

the current watering cycle is

 

flowering stage: 2mins per 2 hours for 6 repetitions when lights are on only (starting when lights start and last watering 2 hours before lights out). each crop box would receive approximately 3 litres in 2 mins.

 

vegetative stage: - 1 min every 3 hours for 6 repetitions (18 hr cycle). in 1 min each crop box would receive @ 1.5 lts

 

previously, i was using the old manual timers and they were getting 15 mins per 4 hours. i have watering this much for years and the last few crops (especially the current one) very bad pythium and now i also have scarid fly too! using microbial to counter these issues

 

so ive dropped the watering as per above. my concern is two fold. are they receiving enough nutrient solution to remove excess salts? or are they still receiving too much and therefore overwatering. i'm suspecting that the flower room may not be receiving enough at the new watering cycle as i'm noticing 'yellowing' of the tips slightly at the same EC which seems to me to indicate that the excess salts are not getting 'flushed' by enough fresh solution at 3lts per 3 hours.

 

im assumign there must be plenty of others using the old crop box system with grodan slabs and was hoping that you could post your watering cycles and litres so that i try it out!

 

thanks for any help.

 

also how are you guys finding microbial? ive been using it a week on pythium infested plants and i have some amazing fresh growth on the top. seems very good.

[pipeman]

rockwool should only need watering once every 6 hours at the most, more likely once a day is enough.

 

Basically you need to judge the watering on the plants requirements. You don't want the rockwool totally drenched all the time but you don't want it to dry out either.

 

The length of each watering is not important as long as you are watering enough to get some runoff. 1-2 minute drip sounds about right.

 

It is important with rockwool to "pot up" as your clones grow. Putting small clones into big rockwool slabs can make them difficult to water because after a watering the plants won't be able to take up enough of the moisture to dry out the medium enough before the next watering, which will result in less healthy plants due to reduced oxygen availability for the roots.

[Nath]

I hated growing in rockwool.. my parner grew clones in big 30cm x 30cm+ rockwool slabs before they went into cocopeat/clay rock 40L tubs and nursing the clones everyday was horrible.. Id have to check each one and make sure it was dry, otherwise there would be green mould growing on them. I generally watered the clones from once every two days to daily.

[Gazza2001au]

Nath, theres your problem 30cmx30cm u only needed 1"x1" as u were planting in coco its a good rule of thumb if ur in doubt ask! and u cant go wrong

[Nath]

Nath, theres your problem 30cmx30cm u only needed 1"x1" as u were planting in coco its a good rule of thumb if ur in doubt ask! and u cant go wrong 

<{POST_SNAPBACK}>

 

 

I know that thx, but he gets 9lbs every 12 weeks from 6x 600w lights, and I was getting 1/2 so I couldnt really complain too much I stopped growing with him because of his stupid methods, and he does some stupid crap which will get him caught, I dont need that risk.

[Roadblock]

Hi

 

The biggest mistake you can do with Rockwool is overwater , Pipemans every 6 hrs is about right once they are well established , when they are powering you can run the pump all day and its ok but in the early part be carefull , common sense here feel the weight of the pot if its full of water dont water them .

 

Clones in Rockwool cubes - have the cube just moist right through not wet , have a socked cube in your hand and squeeze it out , what you have then is a very good moisture air ratio for clones , try and keep it at this level by just dunking the bottom 1/4 inch into water when the cube gets a little dry .

Rockwool cubes and clones is critical , dont have heavy wet cubes .

 

Transplanting into bigger pots , feed once every 2 days untill you see roots at the drain holes , have this feed mixture very low nutrient strength and when you feed make sure you have good flow , Rockwool is about Flow .

Once they are hitting thier straps start increasing the times depending on your own conditions , just remember when you feed to have good flow volume that really flushes out the pot .

 

Rockwool is a great medium but you got to know how to work with it , common sense , not too wet and good flushing flow when you feed .

 

Rod