Say are roots just water sponges or do they they have selective capacity at the molecular level?
As I was thinking that with sipping the plant can extract what she needs from a hot nutrient cocktail and not use what she doesn't need.
And with watering from the top you kinda force all the roots to absorb nutrients as they've been thirsty and you drench them which means they will absorb water directly but that's different to the roots themselves pulling nutes and moisture out of the soil or out of the water channel.
As otherwise I can't explain why my plant was so happy having her feet in what I think is going to be quite the mess of a res with them biocanna nutes as the res smells like dead sea creatures.

A quick google gave me this abstract :

The barrier function of plant roots: biological bases for selective uptake and avoidance of soil compounds​

The root is the main organ through which water and mineral nutrients enter the plant organism. In addition, root fulfils several other functions. Here, we propose that the root also performs the barrier function, which is essential not only for plant survival but for plant acclimation and adaptation to a constantly changing and heterogeneous soil environment. This function is related to selective uptake and avoidance of some soil compounds at the whole plant level. We review the toolkit of morpho-anatomical, structural, and other components that support this view. The components of the root structure involved in selectivity, permeability or barrier at a cellular, tissue, and organ level and their properties are discussed. In consideration of the arguments supporting barrier function of plant roots, evolutionary aspects of this function are also reviewed. Additionally, natural variation in selective root permeability is discussed which suggests that the barrier function is constantly evolving and is subject of natural selection.
 
Highya Stardog, guys,

Love the SIP construct. Well thought out, and very nice looking build. Should work very nicely!! Happy Smokin'
 
Here's a question for all.
In my first SIP grow I found a floor in the pot of soil maybe 4 to 6 inches up from the bottom. Bottom section filled with dense roots and the top section almost none.

I'm having a wonder on this. I wonder if when making the feet wicks I didn't do it fully proper. I remember pouring soil in and with my fist pressing down over the wick sections to create the wick. I don't remember refilling and doing it again. I wonder if the floor is where I first left my press and if I topped that off and repressed, would the floor be higher affording more root zone? Top pic shows the floor at the bottom of the pot of roots and bottom pic is the densely rooted floor. I'd like to see that soil more root populated up top but don't want to top water unless I have to to get it done. I'm thinking of trying more soil and re pressing the wick section better.
Any thoughts?

 
Could be a combination of things like how well your mix naturally wicks, how firmly you pressed in the wicking feet, and your plastic cover.

I get roots right up into my top mulch, but I use organic materials (leaf mold in my case) and regularly mist the top surface (twice a day in veg and once a day in flower) and also periodically top water. I'd suggest you try your normal bark mulch on your next round, and maybe pack the wicking feet down, refill them and pack down again until you get up to the pot floor level and see if that combination makes a difference.

More roots filling the top part of your container might give you a bigger harvest, but then you'd have to deal with storage issues. :laughtwo:
 
Could be a combination of things like how well your mix naturally wicks, how firmly you pressed in the wicking feet, and your plastic cover.

I get roots right up into my top mulch, but I use organic materials (leaf mold in my case) and regularly mist the top surface (twice a day in veg and once a day in flower) and also periodically top water. I'd suggest you try your normal bark mulch on your next round, and maybe pack the wicking feet down, refill them and pack down again until you get up to the pot floor level and see if that combination makes a difference.

More roots filling the top part of your container might give you a bigger harvest, but then you'd have to deal with storage issues. :laughtwo:
Hmmmm I wasn't thinking to revert to my bark but that would certainly allow me more control. Hah! Maybe I was wishing for less control. You're right about top misting but I may want to try skipping that and going with preparing the pot thoughtfully and covering with the covers again to see what happens. I'm relieved to hear you get roots to the top in your grows!
 
I do think that plastic cover is not ideal. It doesn't breathe that well, doesn't offer any microbe habitat, doesn't allow efficient tending to the soil surface, etc. With a natural material you get all of those things.

The plastic cover suggestion comes from using the planters outdoors to help keep the rain from saturating the media. Indoors you don't have that issue so you can use a much more effective mulch for your covering layer.
 
I feel pretty strongly from experience that the plastic cover is the superior solution in many SIPs and especially Earthbox. It's obviously not airtight, and up top all you need is basic gaseous exchange (created gases may exit - often created by microbes and other chemical reactions) Especially in the case of grows in which microbial activity is critical, a plastic cover offers a total light-block and excellent moisture retention, permitting the top inch of soil to be fully utilized by microbes and plant roots.

It's also necc. to have the plastic cover fit over the top of the pot, as opposed to just laying a cut-to-size plastic piece on top. This is because the cut-to-size plastic will force all of the atmo gasses - aka dry-out forces - to work only at the very edge where the dirt ends and pot begins. Focusing those forces on this small area quickly dries out that critical boundary area and as you know, with containers, whether SIP or traditional, there are a lot of important roots there picking up the moisture that condenses out on the inside face of the pot. That's not the only reason they use elasticized cover fitting like a shower cap, the other is for outdoor use to prevent heavy rains from washing soil into the reservoir, but this edge-drying effect is very pronounced if you just lay plastic on top of soil.

I've done straw, burlap, and even sand, and best results and fewest issues with a nice fitted cover stretching over the pot edges. It really releases nutrients in soil's top layer, encourages root development in the layer and increases microbe activity significantly. You can make your own with panda-plastic, facing the white side out, and instead of elasticized just cut to fit over pot and affix in place with tape or get fancy by affixing small weights. With tape make sure not to seal it up, and leave lots of untaped edges for gaseous exchange.

A lot of people use straw and other bio mulches which is fine, obviously. However I was surprised that a plastic cover became my pref, and I do want to warn again against a cover of plastic laying just on top - it will, for that edge barrier area where traditionally roots find a lot of moisture due to condensation, dry it and only it shockingly quickly.

It's not an intuitively easy effect to forsee, but is pronounced in reality. You'll see a space develop between the edge of soil and inside of pot as edge soil dries and contracts, in the very ast spot you want it drying because of high root density against inside pot surface. Even laying cardboard, fitted, on top will force that boundary space to dry out, but since air gets to more of the rest of the soil, the drying edge-effect is less pronounced.

Otter, I had trouble understanding what the issue was that you raised in the post, though I'm still trying! I wanted to share this lesson regarding laying a cut-to-shape plastic cover laying on the soil inside pot's edges. Sorry for the word walls, I will keep trying to be more succinct, and find you some pics.
 
Any thoughts?
My thought is that because it was covered the whole time, you never knew if the top of the soil ever got moist. It sure looks like it didn't or there would be roots there. So either there was a wicking issue or maybe the res needed a lot more water than it was getting in order for it to work it's way all the way to the top.

I do think that plastic cover is not ideal. It doesn't breathe that well, doesn't offer any microbe habitat, doesn't allow efficient tending to the soil surface, etc. With a natural material you get all of those things.
I feel pretty strongly from experience that the plastic cover is the superior solution in many SIPs and especially Earthbox.
Can you guys sort this out and report to @Maritimer? He's completely covered his with plastic as well.
 
I feel pretty strongly from experience that the plastic cover is the superior solution in many SIPs and especially Earthbox. It's obviously not airtight, and up top all you need is basic gaseous exchange (created gases may exit - often created by microbes and other chemical reactions) Especially in the case of grows in which microbial activity is critical, a plastic cover offers a total light-block and excellent moisture retention, permitting the top inch of soil to be fully utilized by microbes and plant roots.

It's also necc. to have the plastic cover fit over the top of the pot, as opposed to just laying a cut-to-size plastic piece on top. This is because the cut-to-size plastic will force all of the atmo gasses - aka dry-out forces - to work only at the very edge where the dirt ends and pot begins. Focusing those forces on this small area quickly dries out that critical boundary area and as you know, with containers, whether SIP or traditional, there are a lot of important roots there picking up the moisture that condenses out on the inside face of the pot. That's not the only reason they use elasticized cover fitting like a shower cap, the other is for outdoor use to prevent heavy rains from washing soil into the reservoir, but this edge-drying effect is very pronounced if you just lay plastic on top of soil.

I've done straw, burlap, and even sand, and best results and fewest issues with a nice fitted cover stretching over the pot edges. It really releases nutrients in soil's top layer, encourages root development in the layer and increases microbe activity significantly. You can make your own with panda-plastic, facing the white side out, and instead of elasticized just cut to fit over pot and affix in place with tape or get fancy by affixing small weights. With tape make sure not to seal it up, and leave lots of untaped edges for gaseous exchange.

A lot of people use straw and other bio mulches which is fine, obviously. However I was surprised that a plastic cover became my pref, and I do want to warn again against a cover of plastic laying just on top - it will, for that edge barrier area where traditionally roots find a lot of moisture due to condensation, dry it and only it shockingly quickly.

It's not an intuitively easy effect to forsee, but is pronounced in reality. You'll see a space develop between the edge of soil and inside of pot as edge soil dries and contracts, in the very ast spot you want it drying because of high root density against inside pot surface. Even laying cardboard, fitted, on top will force that boundary space to dry out, but since air gets to more of the rest of the soil, the drying edge-effect is less pronounced.

Otter, I had trouble understanding what the issue was that you raised in the post, though I'm still trying! I wanted to share this lesson regarding laying a cut-to-shape plastic cover laying on the soil inside pot's edges. Sorry for the word walls, I will keep trying to be more succinct, and find you some pics.
Interesting thoughts, @ReservoirDog . Sounds like you've had good success with the plastic cover, and the points you make about the type one uses are important if that's the route you choose.

For me though a good, and thick, organic mulch will continue to be the way I grow. A good organic mulch should allow gas exchange across the entire surface, rather than just at the edges if using a cut-to-fit cover, or just through the planting hole if using the shower-cap style, although maybe you're saying with the shower cap version the plastic sits above the soil with an air gap allowing gas exchange more broadly? I do know the Earthbox set-up instructions say to mound the soil (again to help with rain shedding) so maybe that's not about gas exchange.

An organic mulch adds the extra benefits of organic material to help feed the soil microbes along with the moisture retention of the other. Also, there is something quite off-putting to me about using a plastic cover like that in the grow (which probably doesn't make much sense since I use plastic buckets to house the soil mix. :hmmmm: )

But, if not growing outdoors where rain is a factor, it seems to me that in an organic grow, an organic mulch brings the moisture retention properties that the plastic does, does it in a superior way, and then brings other benefits along the way.

Maybe if I were using chemical nutes I'd feel differently, but for me ixnay on the asticplay.
 
Yeah, thanks for this guys... or whoamwhatif-ever you are. It's very helpful. More word walls though...

Yup, my main point is, people are having very good results with a plastic showercap or DIY over-hanger, elastic, whatever.

To preface my responses let me say this as straightforwardly as I can (don't make fun).

Once I'd tried all (ok, some - and then some more) of the normal things for mulch and my curiosity over time slightly broke down my instinctual, au natural aesthetic and my at the time, I admit, doctrinal support for ''the natural'' in many things. Guys I've lived completely outside of civilization for two half-decade stretches, non-stop no 'breaks' on my wits and oatmeal. I've been since a small child completely disinterested in material goods that are either not practically useful or stunningly beautiful. ,

I don't want any damn tacky shower caps on my plants! Look, I am arrogant enough to decide I will create the one perfect, ultra-natural, enzymatically composted, seedling-to-harvest, easiest-to-use, bio-redemptive, fertilizer and do it at zero opportunity or sustainment cost, full stop. I don't want no damn shower cap on my plants!

But I do have a shower cap on my plants, so there must be a reason.

lthough maybe you're saying with the shower cap version the plastic sits above the soil with an air gap allowing gas exchange more broadly?
Ding ding ding ding! Nice one Avi! That's exactly it. Consider, say you put your crumbles, then your alfalfa (sp), then your shower cap. What do you think its like down in the earth, all the time? Dark, wet. We're trying to get these three materials exchanging microbial life, developing a diversity and then exploding the population, and we need it to be pulled down into that earth as quickly - efficiently - as possible. This process simply takes place more quickly when you pop a tent over it. It's not a replacement, its an accelerator.
Also, there is something quite off-putting to me about using a plastic cover like that in the grow
There absolutely is, and this is why I refused to even think about it for more than a year. No shit bruv.
Maybe if I were using chemical nutes I'd feel differently
Maybe if things were just a little less, "natural"? But you'll never do that - so you're saying you dont want to think about it. That's cool man. I can't argue with a brother over something that I just did myself, only tell him what happened, how I changed.
 
What about under lights the reflective benfiys - less so the organic aspect, some holes for airflow but some light reflection as well as that evaporation effect under some hot lights, forcing the wick effect as well?

Just throwing it out there as I’m thinking about throwing something on a Solo SIP under lights with Co2 in coco and trying to optimise!

Nick
 
My thought is the cover could be a problem with getting root growth on top , I know you cover soil in gardening to keep weeds down . Just thinking out loud.
It was tight.
I do think that plastic cover is not ideal. It doesn't breathe that well, doesn't offer any microbe habitat, doesn't allow efficient tending to the soil surface, etc. With a natural material you get all of those things.

The plastic cover suggestion comes from using the planters outdoors to help keep the rain from saturating the media. Indoors you don't have that issue so you can use a much more effective mulch for your covering layer.
Ok so I have to agree with you. But I just read on and Rezdog is making sense too. I did just get 12.5 oz's this inaugural run. I'm happy with the general outcome, very happy! It's tweak time and this has my eye as something that may be improvable. Maybe if this area of soil is used my calcium def may not have appeared? Who knows. I think improving my wick making when I make up a pot will raise the root table because moisture will be wicked higher.
What about a fabric wick sitting vertical in the soil? :idea:
I had trouble understanding what the issue was that you raised in the post, though I'm still trying! I wanted to share this lesson regarding laying a cut-to-shape plastic cover laying on the soil inside pot's edges. Sorry for the word walls, I will keep trying to be more succinct, and find you some pics.
Hey Dog, your experience is priceless, thanks! I'm leaning to agree with you.
Doing a rootopsy I found a significant layer of soil that had what I feel was light root population. I could easily sink my hands in to remove it from the pot, where the lower table of roots I needed dynamite. There were roots but few. I may be able to raise the water table by paying attention to details when I make the pot up. Maybe a wick in there too, one thing at a time.
My thought is that because it was covered the whole time, you never knew if the top of the soil ever got moist. It sure looks like it didn't or there would be roots there. So either there was a wicking issue or maybe the res needed a lot more water than it was getting in order for it to work it's way all the way to the top.



Can you guys sort this out and report to @Maritimer? He's completely covered his with plastic as well.
I think both would be helpful. The new pots have a constant fill. That might help. And I can be more thoughtful next time I make pots up. And maybe a wick someday?

Maritimers SIP grow is looking great! Those pots hold a load of soil! He's going to have a grow on his hands!
 
What about under lights the reflective benfiys - less so the organic aspect, some holes for airflow but some light reflection as well as that evaporation effect under some hot lights, forcing the wick effect as well?

Just throwing it out there as I’m thinking about throwing something on a Solo SIP under lights with Co2 in coco and trying to optimise!

Nick
Hey Nick. Good point.
 
What I inarticulately tried to explain the first time is studies show light that is reflected to the bottoms/undersides of leaves contributes as much as 20-30% more to the plant “engine”

Maybe the evaporation effect of leaving top un covered helps with encouraging the wick effect. Dunno. Maybe its good at early stage?

But I reckon airflow I’m prioritising as well. Not one cover for one thing to the detriment of airflow. I’m gonna try a little tin foil with holes tomorrow. But loose fit. Pencil sized holes for air and whacky light reflections maybe a bonus from puncture holes. Never know your luck!

Nick
 
Very interesting points on a top cover of the soil. I'm considering a SIP for my next grow which would be outdoors, but consideration for both excess rainfall and hot dry weather does have me thinking of whether a plastic cover would be good for reducing excess rainfall problems and also reducing the top soil layer from becoming too dry for roots to live.

If I use plastic I'd possibly have to extend it to go over the pot rim to minimise the risk of heavy rainfall, or in that case perhaps any pooling water that soaks down the soil at the side of the pots will simply run out the overflow hole where most of the soil is not left overly soaked. I dunno. Up until now I have preferred organic mulches on top, the worms in the soil like that.

But in saying that, I have often seen worms quite happily living underneath some plastic on the ground. On one of my compost bins I have a stone block on the plastic lid to keep it from being blown off in the wind, and usually after rainfall when I next go to lift the lid, I find worms between the stone and plastic top of the lid, so even though plastic is not something I have not used, worms at least don't seem to be bothered living on it or under it.
 
Ah, @StoneOtter now I understand what your problem was. I am dense sometimes, dude, for real and it's random as hell, left-field stuff, fair warning all concerned.

It really is normal to have a dryer section in the top of a planter that is narrow and tall, as opposed to the inline flat tray style of the other model. I have some tall-draws I've built and it's clear that the moisture becomes harder to pull up the higher you get. Yes, it's a thing. It should be expected, and not necc. sub-optimal I have found.

Hydrotropism is a very powerful effect - these plants are programmed to respond positively to an obvious moisture gradient. It triggers signals for root growth and exploration. That's what trad potted plants do when we douse and dry them but it's inefficient for many reasons. But what they are trying to respond to, even in the trad. container, is the genetic programming of hydrotropism: to find and exploit the water source and if secured exploit the rest as it suits them. You just have a "taller plant" Otter.

But I would top dress amendments, then mulch on top with hay or alfalfa breathable, gently give a quart of something sweet to drink and pop the shower cap on top.

But that's my understanding, my experience and my perspective. I'm frankly more interested in yours and look forward to whatever you do, hoping that the differences enlighten us. I don't think you have a problem.

Pack those wicking feet good, but maybe just at the bottom and keep an even compaction the rest of the way. A major asset of SIPs we rarely think of is that every time we watered our trad. containers, we were compacting the soil a little bit more than it would have been otherwise. I know the soil compacts naturally over time, but it compacts even more when you topwater, and that is energy the plant has to use to extend those roots.
 
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