Smart Pots

[onegreenday]

if only they could be square...

make your own with weed-block fabric to any shape you have a container for (think milk crate) and voila.

 

[mad librettist]

make your own with weed-block fabric to any shape you have a container for (think milk crate) and voila.

that is simple and pure genius. Thanks!

 

[justiceman]

Hey there,



That won't help drainage, it's a myth. But what it does do is raise the perched water table and increase the % of unavailable water (that which the plant can't use), and increase the water-filled porosity verses air porosity (when smaller media parlites wedge between the hydroton thus lowering the pore space.

It's best to use the same media in container only, no so-called drainage layer.

To increase drainage grow in a taller container, the height is a controlling factor of water held and drainage of water, more water drains from a taller containers due to a greater % of air porosity.



HTH

So drainage layers are a myth? how so? I always thought they helped but then again, I checked my root ball after harvest and the 2 inch perlite layer at the bottom of the pot was very wet compared to the soil.

 

[chef]

I'm going to try 1" of perlite/charcoal in the bottom. It can't hurt?

 

[generalgrievous]

Man these pots seem like an awesome idea. I have done a bit of research. No to mention the good info in this thread. I haven't gone through that much of it yet though. I was wondering if it is advised to transplant from a smaller smart pot to a bigger one? i am assuming NO because the roots would rip as they are attached to the pot. I am assuming it would be better to start small plants in small plastic pots and make there final container a smart pot?

I am going to do coco next run and I am considering using smart pots with it.

i use 2 gl. SmartPots with coco/perlite...... i veg in beer cups.... transplant and flip.....the growth rate after this is phenomenal.....

 

[secondtry]

Hey there justicman,

(let me know if this helps explain matters, if not I can go more in-depth for you)

So drainage layers are a myth? how so? I always thought they helped but then again, I checked my root ball after harvest and the 2 inch perlite layer at the bottom of the pot was very wet compared to the soil.

It's about the perched water table and how I mentioned smaller soil particles will fit between spaces of lager hydroton which tends to increase perched water table and water filled porosity at bottom (reducing the size of pores, less air pores too), making a greater % of unavailable water (plants can't use that water). This interlocking of different sized particles decreases drainage as there are less large water pores (mesopores) with easier drainage because they hold water lower water tension; that is important because the bottom of the container has the highest water tension.

To decrease (relatively) the perched water table, and increase % air porosity and also drainage grow in a taller container, this is important with soilless mixes like peat and coir; 30 cm or 45 cm seems good to me.

Here is info which should help you, but some of it is missing the big picture and other more important soil physics issues, for example the author focuses very heavily upon perched water table which is not the most important concern. However, it will help explain why not to use a 'drainage layer':


"Container Soils - Water Movement and Retention"
A Discussion About Soils
http://forums2.gardenweb.com/forums/load/contain/msg0420085231701.html?102

As container gardeners, our first priority should be to insure the soils we use are adequately aerated for the life of the planting, or in the case of perennial material (trees, shrubs, garden perennials), from repot to repot. Soil aeration/drainage is the most important consideration in any container planting. Soil is the foundation that all container plantings are built on, and aeration is the cornerstone of that foundation. Since aeration and drainage are inversely linked to soil particle size, it makes good sense to try to find and use soils or primary components with particles larger than peat. That components retain their structure for extended periods is also extremely important. Pine and some other types of conifer bark fit the bill nicely and I’ll talk more about them later.

The following also hits pretty hard against the futility of using a drainage layer in an attempt to improve drainage. It just doesn't work. All it does is reduce the amount soil available for root colonization. A wick will remove water from the saturated layer of soil at the container bottom. It works in reverse of the self-watering pots widely being discussed on this forum now.

Since there are many questions about soils appropriate for use in containers, I'll post basic mix recipes later, in case any would like to try the soil. It will follow the Water Movement info.

Consider this if you will:

Soil need fill only a few needs in plant culture. Anchorage - A place for roots to extend, securing the plant and preventing it from toppling. Nutrient Sink - It must retain sufficient nutrients in available form to sustain plant systems. Gas Exchange - It must be sufficiently porous to allow air to the root system and by-product gasses to escape. And finally, Water - It must retain water enough in liquid and/or vapor form to sustain plants between waterings. Most plants could be grown without soil as long as we can provide air, nutrients, and water, (witness hydroponics). Here, I will concentrate primarily on the movement of water in soil(s).

There are two forces that cause water to move through soil - one is gravity, the other capillary action. Gravity needs little explanation, but for this writing I would like to note: Gravitational flow potential (GFP) is greater for water at the top of the container than it is for water at the bottom. I'll return to that later. Capillarity is a function of the natural forces of adhesion and cohesion. Adhesion is water's tendency to stick to solid objects like soil particles and the sides of the pot. Cohesion is the tendency for water to stick to itself. Cohesion is why we often find water in droplet form - because cohesion is at times stronger than adhesion, water’s bond to itself can be stronger than the bond to the object it might be in contact with; in this condition it forms a drop. Capillary action is in evidence when we dip a paper towel in water. The water will soak into the towel and rise several inches above the surface of the water. It will not drain back into the source. It will stop rising when the GFP equals the capillary attraction of the fibers in the paper.

There will be a naturally occurring "perched water table" (PWT) in containers when soil particulate size is under about .125 (1/8) inch.. This is water that occupies a layer of soil that is always saturated & will not drain from the portion of the pot it occupies. It can evaporate or be used by the plant, but physical forces will not allow it to drain. It is there because the capillary pull of the soil at some point will surpass the GFP; therefore, the water does not drain, it is "perched". The smaller the size of the particles in a soil, the greater the height of the PWT.

If we fill five cylinders of varying heights and diameters with the same soil mix and provide each cylinder with a drainage hole, the PWT will be exactly the same height in each container. This saturated area of the pot is where roots seldom penetrate & where root problems frequently begin due to a lack of aeration. Water and nutrient uptake are also compromised by lack of air in the root zone. Keeping in mind the fact that the PWT height is soil dependent and has nothing to do with height or shape of the container, we can draw the conclusion that: Tall growing containers will always have a higher percentage of unsaturated soil than squat containers when using the same soil mix. The reason: The level of the PWT will be the same in each container, with the taller container providing more usable, air holding soil above the PWT. Physiology dictates that plants must have oxygen at the root zone in order to maintain normal root function.

A given volume of large soil particles has less overall surface area when compared to the same volume of small particles and therefore less overall adhesive attraction to water. So, in soils with large particles, GFP more readily overcomes capillary attraction. They drain better. We all know this, but the reason, often unclear, is that the height of the PWT is lower in coarse soils than in fine soils. The key to good drainage is size and uniformity of soil particles. Mixing large particles with small is often very ineffective because the smaller particles fit between the large, increasing surface area which increases the capillary attraction and thus the water holding potential.

When we add a coarse drainage layer under our soil, it does not improve drainage. It does though, conserve on the volume of soil required to fill a pot and it makes the pot lighter. When we employ this exercise in an attempt to improve drainage, what we are actually doing is moving the level of the PWT higher in the pot. This simply reduces the volume of soil available for roots to colonize. Containers with uniform soil particle size from top of container to bottom will yield better and more uniform drainage and have a lower PWT than containers with drainage layers. The coarser the drainage layer, the more detrimental to drainage it is because water is more (for lack of a better scientific word) reluctant to make the downward transition because the capillary pull of the soil above the drainage layer is stronger than the GFP. The reason for this is there is far more surface area for water to be attracted to in the soil above the drainage layer than there is in the drainage layer, so the water "perches".

I know this goes against what most have thought to be true, but the principle is scientifically sound, and experiments have shown it as so. Many nurserymen are now employing the pot-in-pot or the pot-in-trench method of growing to capitalize on the science.

If you discover you need to increase drainage, you can simply insert an absorbent wick into a drainage hole & allow it to extend from the saturated soil to a few inches below the bottom of the pot, or allow it to contact soil below the container where it can be absorbed. This will successfully eliminate the PWT & give your plants much more soil to grow in as well as allow more, much needed air to the roots.

Uniform size particles of fir, hemlock or pine bark are excellent as the primary component of your soils. The lignin contained in bark keeps it rigid and the rigidity provides air-holding pockets in the root zone far longer than peat or compost mixes that too quickly break down to a soup-like consistency. Conifer bark also contains suberin, a lipid sometimes referred to as nature’s preservative. Suberin is what slows the decomposition of bark-based soils. It contains highly varied hydrocarbon chains and the microorganisms that turn peat to soup have great difficulty cleaving these chains.

In simple terms: Plants that expire because of drainage problems either die of thirst because the roots have rotted and can no longer take up water, or they starve/"suffocate" because there is insufficient air at the root zone to insure normal water/nutrient uptake and root function.

To confirm the existence of the PWT and the effectiveness of using a wick to remove it, try this experiment: Fill a soft drink cup nearly full of garden soil. Add enough water to fill to the top, being sure all soil is saturated. Punch a drain hole in the bottom of the cup & allow to drain. When the drainage stops, insert a wick into the drain hole . Take note of how much additional water drains. Even touching the soil with a toothpick through the drain hole will cause substantial additional water to drain. This is water that occupied the PWT before being drained by the wick. A greatly simplified explanation of what occurs is: The wick "fools" the water into thinking the pot is deeper, so water begins to move downward seeking the "new" bottom of the pot, pulling the rest of the water in the PWT along with it. If there is interest, there are other simple and interesting experiments you can perform to confirm the existence of a PWT in container soils. I can expand later.

I remain cognizant of these physical principles whenever I build a soil. I haven’t used a commercially prepared soil in many years, preferring to build a soil or amend one of my 2 basic mixes to suits individual plantings. I use many amendments when building my soils, but the basic building process starts with conifer bark and perlite. Sphagnum peat usually plays a minor, or at least a secondary role in my container soils because it breaks down too quickly and when it does, it impedes drainage and reduces aeration.

 

[secondtry]

hey,

I'm going to try 1" of perlite/charcoal in the bottom. It can't hurt?

Sorry to say it can and it's better to increase the height of the container to increase drainage than to add a drainage layer. Using the same media in the whole container is best IMO. HTH

 

[flyingkite]

Sounds awesome!

 

[Moldy Dreads]

hey,



Sorry to say it can and it's better to increase the height of the container to increase drainage than to add a drainage layer. Using the same media in the whole container is best IMO. HTH

I agree, I see alot of newbys adding layers of hydroton to the bottom. When I did this years ago, I remember all it did was limit my root groth right up to the hydroton, the roots did not penetrate and it was always wet, poor drainage.I use medium all the way now. HYDROTON is best alone as a hydro medium in a system with many floods IMO.

 

[Clackamas Coot]

Assuming that one is using 10-gallon (or less) SmartPots and assuming that the individual pots are in the large saucers, cutting some lengths of PVC pipe and placing them in the saucer under the pot will give you the drainage you might feel is necessary.

HTH

CC

 

[jjfoo]

I'm going to try 1" of perlite/charcoal in the bottom. It can't hurt?

are you asking if I can hurt or saying it can't? you are using a question mark on a sentence


actually it can hurt, unless you doubt the science behind it...

you should do an experiment to see for yourself

 

[justiceman]

Excellent read!

Excellent read!

Hey secondtry thank you so much for that reply. Wow that was a great read. And it made a lot of sense too. the GFP and the PWT are very interesting concepts that I never considered in that manner.

"The coarser the drainage layer, the more detrimental to drainage it is because water is more (for lack of a better scientific word) reluctant to make the downward transition because the capillary pull of the soil above the drainage layer is stronger than the GFP. The reason for this is there is far more surface area for water to be attracted to in the soil above the drainage layer than there is in the drainage layer, so the water "perches".

That specific paragraph really summed up the idea after learning about GFP and the PWT. Thanks again for posting that. It cleared up my question no doubt.

 

[secondtry]

Hey JM,

Glad to be of help. If you want to learn more about soil physics click the link in my sig to the soilless media. Here are to good resources online:

Media: Rooted in Success
Dept. of Floriculture and Ornamental Horticulture, Cornell University
(this is where much info from the article was sourced-some is outdated)
http://web.archive.org/web/20080521...partment/faculty/good/growon/media/index.html



Physical properties of container media
James Altland, Ph.D., North Willamette Research and Extension Center, Oregon State University
http://www.oregonstate.edu/dept/nur.../physical_properties/physical_properties.html



Horticulture Substrates Lab
North Caroline State Unviiery
http://www.ncsu.edu/project/hortsublab/pubs/index.html


Lab/Unit 7 - Soil Water
Regents of the University of Minnesota, 2006
http://www.soils.umn.edu/academics/classes/soil2125/doc/slab8h20.htm

HTH

 

[secondtry]

This info by James Atland, Ph.D is not the figures to go by for media at container capacity (CC; the same as field capacity for soil but CC is for soilless media), AFAIK it's best to use the NCSU porometer method and resulting definitions of pore size: (416-10 micron) available water; (10-0.2 micron) buffer water; and (< 0.2 micron) unavailable water.

"Physical properties of container media"
James Altland, Ph.D. North Willamette Research and Extension Center. Oregon State University
http://oregonstate.edu/dept/nursery.../physical_properties/physical_properties.html

(1 mm = 1,000 microns)

Pore size affects available water content, drainage, and the distribution of water in containers. Small pores (<0.01 mm) hold water so tightly that it is unavailable for plant uptake; pores between 0.01 and 0.8 mm in diameter contain water that is readily available for plant uptake; and pores between 0.8 to 6 mm are so large that they do not hold water and are mostly filled with air.

 

[Dave Coulier]

Secondtry, its nice to see someone else who has stumbled upon Tapla(Al) at gardenweb. A lot can be learned by his threads there. I feel I learned more from his threads, than what Ive learned on MJ forums. No bullshit, no myths, no forum thinking. Just knowledge from him.

Thanks for the links. Its stuff Ill gladly read. Im always reading shit like that.

 

[Clackamas Coot]

2ndTry

For growers of nursery stock the shift to SmartPots was an easy deal. In an open field growing operation, the traditional plastic lipped nursery pots can hit temperatures up to 120F degrees. Roots do NOT grow with these temps - period.

Given the added benefit of reduced soil temperatures, the SmartPots (as well as any/all auto-pruning pots) technology allows for maximum transfer of oxygen to the root mass meaning that one can use a 'more dense' soil than in traditional plastic pots.

From the 'For whatever it means' department at the home office in Butt Crack, Texas.

HTH

CC

 

[B. Friendly]

smart pots i can understand. they would reduce heat by keeping the pot wet, da.... plus plus... But airpots seem like a scam to me. I mean my veg is 4 to 6 weeks tops, 3 gal have always been good enough, if i am not to root bound what good is an airpot? I think Indifferent said they were bunk

 

[GET MO]

I found no difference in airpots compaired to regular pots. actually I take it back, airpots took more water to maintain.

SMART POTS: Dependent on strain. some strains love um other strains seem to not make a difference.

 

[Clackamas Coot]

smart pots i can understand. they would reduce heat by keeping the pot wet, da.... plus plus... But airpots seem like a scam to me. I mean my veg is 4 to 6 weeks tops, 3 gal have always been good enough, if i am not to root bound what good is an airpot? I think Indifferent said they were bunk

B. Friendly

I have no experience with the product called 'Air Pots' so I can't really comment.

Sorry.

CC

 

[secondtry]

2ndTry

For growers of nursery stock the shift to SmartPots was an easy deal. In an open field growing operation, the traditional plastic lipped nursery pots can hit temperatures up to 120F degrees. Roots do NOT grow with these temps - period.

Given the added benefit of reduced soil temperatures, the SmartPots (as well as any/all auto-pruning pots) technology allows for maximum transfer of oxygen to the root mass meaning that one can use a 'more dense' soil than in traditional plastic pots.

From the 'For whatever it means' department at the home office in Butt Crack, Texas.

HTH

CC

Thanks CC,

You like using them when growing cannabis indoors?

RE: 'more dense', do you mean bulk density? Where did that claim come from, a seller/manufacture of the SmartPot? I am curious why they would suggest that (I don't see the link with media density), do you have any more info?

Snowing here!