SIP thread -- (Sub-Irrigated Planter)

PDX Joe

Well-Known Member
Hmm, well... the base is peat/ coco with some perlite... so that part is a good start to having a lightweight mix that can achieve proper capillary action to wick water up. However, the thing that would concern me about this mix is that they imply it's pretty hot stuff with the way they want you to use it. They don't want you to plant directly into the mix, but place it at the bottom of more inert mix. I assume this is in order to avoid burning the plants and to get a slow release of nutes.

This could be a problem in a SIPS for a couple reasons. If the mix is too dense then it may become too saturated because it will be all down near the reservoir and this may prevent water from properly wicking up into the rest of the grow medium. Stuff like worm castings, guano and humus can potentially make the medium too dense and therefore too wet. You could try to put a lot more perlite into it to lighten it up. When I use peat moss I usually amend it with 40% perlite. With a dense mix you might want to go higher than this with perlite.

The other issue is having water percolate up through this hot mix could cause young plants to get too much nutrients early and then not enough later in the grow. But, I'm speculating on this one. The way I apply my fertilizer is actually at the top of the system. I carve trenches along the top outside edges of the bucket grow medium and pour slow release organic powdered fertilizer into the trenches and then cover it over with peat. The water wicks up and slowly activates the nutrients over a long time rather than the powder nutrients getting too wet if it was mixed lower in the SIPS container. Roots radiate out to the trenches of fertilizer as the plant gets larger and need more nutrients. In your case, you could try to use the kind soil around the perimeter of the container in the ratio they suggest and then fill the rest of the container with the inert medium. That way your plant wouldn't be directly in the kind soil, but the denser kind soil wouldn't be at the bottom of the SIPS. You might get a slow release of nutrients similar to the trench technique without affecting water wicking capability.

One other thing I do in peat medium is add a bit of dolomite lime, usually 1-2 tbsp per gallon of medium to provide some calcium throughout the grow. I have also had to supplement with some Cal-Mag in the res later in the grow... especially for tomatoes and cannabis. But, the kind mix might have enough calcium.
 

Weedy willy

Well-Known Member
Can anyone recommend any pre made super soils that I could use? I just really dont have enough time to make my own and let it break down for months.
 

Weedy willy

Well-Known Member
Build a soil web site or just ffof with happy frog organic dry nite is my suggestion
I've used ffof before, but never used the dry fertilizer. How long would it last, would I have to add anything during flowering or would that be all I needed? My main concern is top feeding and messing up the wicking.
 

Weedy willy

Well-Known Member
Hmm, well... the base is peat/ coco with some perlite... so that part is a good start to having a lightweight mix that can achieve proper capillary action to wick water up. However, the thing that would concern me about this mix is that they imply it's pretty hot stuff with the way they want you to use it. They don't want you to plant directly into the mix, but place it at the bottom of more inert mix. I assume this is in order to avoid burning the plants and to get a slow release of nutes.

This could be a problem in a SIPS for a couple reasons. If the mix is too dense then it may become too saturated because it will be all down near the reservoir and this may prevent water from properly wicking up into the rest of the grow medium. Stuff like worm castings, guano and humus can potentially make the medium too dense and therefore too wet. You could try to put a lot more perlite into it to lighten it up. When I use peat moss I usually amend it with 40% perlite. With a dense mix you might want to go higher than this with perlite.

The other issue is having water percolate up through this hot mix could cause young plants to get too much nutrients early and then not enough later in the grow. But, I'm speculating on this one. The way I apply my fertilizer is actually at the top of the system. I carve trenches along the top outside edges of the bucket grow medium and pour slow release organic powdered fertilizer into the trenches and then cover it over with peat. The water wicks up and slowly activates the nutrients over a long time rather than the powder nutrients getting too wet if it was mixed lower in the SIPS container. Roots radiate out to the trenches of fertilizer as the plant gets larger and need more nutrients. In your case, you could try to use the kind soil around the perimeter of the container in the ratio they suggest and then fill the rest of the container with the inert medium. That way your plant wouldn't be directly in the kind soil, but the denser kind soil wouldn't be at the bottom of the SIPS. You might get a slow release of nutrients similar to the trench technique without affecting water wicking capability.

One other thing I do in peat medium is add a bit of dolomite lime, usually 1-2 tbsp per gallon of medium to provide some calcium throughout the grow. I have also had to supplement with some Cal-Mag in the res later in the grow... especially for tomatoes and cannabis. But, the kind mix might have enough calcium.
What kind of powder nutes do you use?
 

Tim Fox

Well-Known Member
I've used ffof before, but never used the dry fertilizer. How long would it last, would I have to add anything during flowering or would that be all I needed? My main concern is top feeding and messing up the wicking.
I have done water only in ffof with fox farms dry nutes mixed in Start to harvest
 

Tim Fox

Well-Known Member
On this grow I used ffof with happy frog dry organic and marine cuisine dry nutes , just water and Cal mag
 

Weedy willy

Well-Known Member
On this grow I used ffof with happy frog dry organic and marine cuisine dry nutes , just water and Cal mag
The website says put in the top inch layer of soil, do you do that or mix with the soil before planting? This is probably what I'm going to try.
 

Tim Fox

Well-Known Member
The website says put in the top inch layer of soil, do you do that or mix with the soil before planting? This is probably what I'm going to try.
hahaha,, i am pretty darn stoned,,,,
I mixed in 1 cup of happy frog dry nute to one bag of FFOF and 1 cup of marine cuisine to the same bag, and 1 cup of domolite lime,, next grow i will probably leave out the lime
 

Weedy willy

Well-Known Member
hahaha,, i am pretty darn stoned,,,,
I mixed in 1 cup of happy frog dry nute to one bag of FFOF and 1 cup of marine cuisine to the same bag, and 1 cup of domolite lime,, next grow i will probably leave out the lime
Thanks, why leave out the lime? I've always added lime
 

Plant Lobbyist

Well-Known Member
I am trying a DiY sip-like run consisting of 102l tough boxes as the res using 3g re-usable grocery bags as the wick and 7g fabric pot for growing sitting on top. 2 for each toughbox.

Wick material is recycled pro-mix hp with some added perlite, vermiculite, epsom, dolomite, rock dust and biologicals. Growing medium is the same + mykos and azos. Plan is to run a few strains to get the hang of it.

First thing I noticed is the wicking function exceeded my expectations. Growing medium might actually be too wet. I have been letting them run under lights for two weeks without plants to get an idea of the base evaporation rate and help offset the low humidity from the cold temps.

The 3g wicks are probably overkill but they make a solid base for the growing section. Has anyone had good experience using some sort of air exchange or injection system? I was thinking just putting in some drinking straws down 6" to get more air into the medium. Pros? Cons? Good? Bad?

In the meantime I am going to let the res almost completely dry out.
 
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