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My latest SWC prototype

Posted by ferretbee 5b (My Page) on
Tue, May 18, 10 at 11:24

My newest SWC with Sungold planted is very experimental, so please keep that in mind:

It's an 18 gallon Rubbermaid tote with a soil bench made from a 14 gallon tote. What makes it different is the PVC pipe framework inside. The PVC structure combines the fill tube, soil bench support, cage support, and reservoir shutoff valve:

- The shutoff valve is just a CPVC valve with the knob removed and a piece of 1/2" copper pipe with 1/2" to 3/8" coupling slipped over the stem and screwed. The valve is really easy to turn with just the copper pipe, I don't think a handle on top is needed, although I may cap it to keep skeeters out.

- The wicks are from rayon mop and sit down inside the PVC frame uprights.

- The fill tube is part of the frame so that any dirt gets flushed from the valve whenever the reservoir is filled.
I used 3/4" PVC for the frame with a 1" for the fill tube to make it easier to fill:

- The soil bench is supported in the middle on the shoulders of the PVC T fittings.
- There is a single wick in the center as a fail safe to allow the bottom 3/4" of water to be accessible to the plant (the valve opening sits about 3/4" from the bottom). I'm going to try drilling a hole through the middle of the valve seat to circumvent this issue.

- The large aeration holes are based upon some of my wicking experiments this past winter. I noticed that landscape fabric against small holes in plastic really restricts drainage, and this design needs the landscape fabric or soil could work down the sides of the bench and wick additional water.

- A tomato cage slips down inside the top caps of the PVC frame. This transfers the load to the ground instead of the soil bench, and makes bot setting up and end of season cleanup much easier.

I hot glued a small piece of insect screen over the drain hole to keep skeeters out. (Last year, I tried landscape fabric over a drain hole and it was a disaster):

It took longer to build than I expected, especially gluing up the PVC frame. I may try one that's just press fit since it's not under pressure.

I'm uncertain if 5 wicks will be sufficient, but it would be easy to add more if needed. I also don't know if the valve will be capable of regulating moisture, or will only work as an on/off switch for the 4 wicks.

I will be adding a fertilizer strip and plastic mulch cover in a few days. The reservoir is also empty right now. I've been having better results by letting the mix drain and settle a bit after setting up rather than starting with a full reservoir.

I'm not recommending anyone try this, it's unproven, possibly silly, and a solid indication that I've officially lost my mind.


Follow-Up Postings:

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RE: My latest SWC prototype

Why not use a basket for the wicking?


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RE: My latest SWC prototype

Why not use wicks for wicking? Just because most SWCs (both DIY and commercial) use a wicking chamber filled with potting mix doesn't mean that it's the only, or even necessarily the best solution.

For this design, wicks were the key to combining the support frame and shutoff valve into a single unit. I've been working on a way to integrate a traditional wicking chamber with this type of frame, and also with various ways to regulate water uptake on the fly. I've been testing out using wicks in my bucket SWCs, and I got the idea to use wicks in this way after seeing a post that mentioned the 'Wickinator' window box water reservoir.

Trying different things is how we learn, and we often gain more knowledge from failures than success. That's how progress is made.

Here is a link that might be useful: Wickinator


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RE: My latest SWC prototype

Nice work, what is the purpose for a shut off valve


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RE: My latest SWC prototype

Hey, Ferret!
Thanks for the pics and the updates! I like to see the latest designs emerging.
I've just put my Sungold (third year I've grown this variety in a container) on my deck.

The Ailanthus in your first pic caught my eye! ;)

Josh


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RE: My latest SWC prototype

dickiefickle:

Just by looking at the design, the shutoff valve is to try to control how much water makes it INTO the pipes, and to the wicks, as a way to control moisture.

It may work, but don't forget that it's off if you turn it off!

BTW: Experimenting is almost always over engineered and complicated. If he finds a few god ideas out of this, the next steps are to simplify. Like he said, "it's unproven, possibly silly, and a solid indication that I've officially lost my mind."

More honest than most of us are to ourselves :)

I like seeing new ideas. My current option for controlling moisture in a swc is soil composition.


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RE: My latest SWC prototype

The valve is used to shut off, or even cut off the supply of water to 4 of the wicks.

I was somewhat frustrated last year by my SWCs that stayed way too wet and vowed to improve this year. I've been attacking the issue from multiple fronts, including the potting mix used and wicking setups. My current thinking is that even when you can optimize both the design and mix, there will still be so many other variables, that being able to adjust the wicking after the initial setup could provide an additional advantage for the plant. I'm also hoping that being able to adjust the wicking will help eliminate some of the trial and error that goes along with DIY SWC designs, and speed up the fine tuning process that takes several seasons to accomplish.

I had a Roma last year in one of my SWCs that did very well. The first main crop was OK, but the fruit wasn't great and had a lot of hollow spots inside (too much water). Toward the end of the season, I removed the mulch cover, stopped filling the reservoir, and switched to top watering. The plant put out a second crop and the fruit was completely different. It was smaller in size, but sweet, tasty, and perfect inside. I'm reminded of the 'dry farmed' Early Girl tomatoes that get such rave reviews. One reason this worked for my Roma was that it was on a covered deck and was a manageable size (a mere 7 ft). My full grown Indeterminate tomatoes with stacked cages in the yard were too unstable without water in the reservoir. I'd initially intended to tie them together for better support, but decided against it last year because I was fighting black speck and spot.

I think that even under ideal conditions the potting mix in SWCs often stay too wet, and sometimes plants do well in them more because they adapt to the wet conditions rather than because the conditions are ideal. External environmental conditions also play a big role (for example, water in a a container, within a plant, and even the air, behaves a lot different at 80 degrees than at 40 degrees).

I'm not saying that current SWCs don't work and aren't great. Despite a terrible season last year I still had a good harvest when many local in-ground gardeners got little or nothing.

I also like the SWCs becasue the majority of my plants will reside across town. I can't attend to them every day, and can't seem to train my sisters to care for them. With the SWCs, I can get them started here, then move across town. I also gave some tomatoes in bucket SWCs as gifts last year and they were much appreciated.

I'm also going to try EngineeredGarden's approach of using 7/64" holes (or single hole in smaller containers) in the wicking basket. I experimented a lot this past winter with wicking chambers and found the approach to have a valid basis. I also believe that wicking chamber diameter is important. Actually, it has more to due with the surface area of mix on contact at the water line rather than the volume of the mix in the chamber. The depth of the soil chamber is also important (the shallower the depth, the easier is is to wick to the top without saturating the mix at the bottom). I also beleive you can reduce the amount of wicking by reducing the size of the opening between the wicking basket and soil chamber. There's lots of ways to adjust how a SWC wicks.


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Sumac

greenman28,

That Sumac is growing in the neighbors' hedge, I should get rid of it for them.


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RE: My latest SWC prototype

Sumac?
It looks almost exactly like my Ailanthus altissima...

Either way, probably best to remove it soon! ;)

Josh


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The fifth wick

imstillatwork,

Don't forget that the middle wick is free of the frame, so even when the valve is off there's still one wick going.

That reminds me, I've seen a commercial SWC that has no wicking whatsoever. It relies upon evaporation instead. That might only work in smaller containers.


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RE: My latest SWC prototype

Any Update; how is this working?

d


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RE: My latest SWC prototype

Pretty good, although I haven't really seen any benefit to the valve yet, but expect to use it later in the season as the weather cools. It's been a very warm and dry season so far, so there hasn't been any reason to limit water. Part of the reason I haven't seen any benefit to the valve yet is I changed my methods this year. I've been using my SWCs as just regular top-watered containers until the plants are well established, then adding the fertilizer strip, plastic mulch cover, and filling the reservoir when the plant starts to get big and/or I have to start watering frequently.

The Sungold in the prototype unit large and productive, but the wicking did fail once during the extreme heat and I had to top water once to restart it. I built 3 of these, the last 2 use 8 wicks in the frame and those didn't have that problem. I need to add a couple of holes near the bottom of the fill tubes to make filling faster as there is too much back-pressure with just the valve as the only place for water to enter the reservoir.

I'm also considering abandoning the Rubbermaid containers as I don't like how flexible they are, and it's getting hard to find the 14 gallon size I like to use for the bench. I also don't like the large aeration holes in the prototype and prefer to use fiberglass insect screen instead of landscape fabric. In fact I think I like using the 'dual tote' method of stacking a 14 gallon inside an 18 gallon instead of using a cut tote flipped for the soil bench.

Using the PVC pipe frame for support of the cage works extremely well, and I use the method in all my 18 gallon tote SWCs. Here's a pic of a PVC frame that is just for soil bench and cage support:

I haven't come to any firm conclusion about using wicks vs. wicking chamber, but I really like using the wicks in my bucket SWCs for convenience reasons. I've also been testing Engineeredgarden's method of using just one or 2 very small holes in the wicking chamber and find those containers are working fine.

Also, my in ground tomato plants are doing better than their 18 gallon SWC counterparts, but growing conditions this year are ideal for in-ground, and the SWC tomatoes were both transplanted later and got less sunlight early on. I've been surprised how well the in ground tomatoes are doing water-wise in the extreme heat we've been having.


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RE: My latest SWC prototype

Thanks to all you guys working on the Earth Tainers, all of the commercial boxes, DIYer's, the mix, the science, etc, and posting your thoughts and results.

I am working on a variable size orifice between the wicking pot in the water and the big pot the tomato plant is in. (5 gallon plant bucket sitting in a 3.5 gallon bucket ~1/2 full with water- wicking basket submerged; mix is what I had on hand, 1:1 Sta-Green potting mix and small pine bark fines)

After building and pre-watering everything, the 5 gallon plant pot (no plant- just an open top to simulate plant demand) maintained mix moisture at a high level, except for the top 1/2 inch, from 4pm yesterday till 8am this morning with an Open orifice. (air 95F to 65 F, ~25% humidity)

closed the orifice at 8am, and will now see if the pot mix dries out a bunch more. I can already see the pot mix drying out significantly. Will let it go till 10 pm, then will check, top water, open the oriface, and go on 24 hour tests.

If I can get this design to make the plant pot Dry to wet, I think this is going to be what I am looking for giving maximum moisture versatility.

Then the challenge is making a much easier to operate oriface; It is now a big flat piece of plastic on a swivel hooked to two opposite facing holes with big zip ties attached to cover or uncover the 5" diameter orifice. There is landscaping screen lining the wicking pot and the bottom of the 5 gallon plant pot.

The water holding resevoir is ~2 gallons, the wicking basket is an old plant pot about 5"diamenter by 4" high, about 12 1/4 holes. I designed all this with a drill in my hand and decided to use what I could find in less than a minute, so compromises were made. (RED GREEN would be proud)

d in colorado.


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RE: My latest SWC prototype

Hi Guys,
I learned about SWC's and started my own SWC garden only this year. Your posts touch two subjects that I also explored this spring. I was going to mention my experiences after harvest but I will try to contribute now.

First, my thanks to Raybo, Josh, Tapla and others who have provided excellent guidance and their years of experience in this forum on SWC's and container media. I did a few modifications to try out. I will leave it to others to decide if any of these are improvements.

Earthtainerearthtainer 2
For an orifice regulator, I made a slide flap from the wick cutout and a pipe strap bar. As you can see in the pix, It slices through the media above the basket. I put about 1 1/2 inch thick muffin top of media over the flap then put the landscape fabric over that. As it turns out, the combination of open wick and media worked fine for my tomatoes this season and I never closed the flap this season.

Another modification I did was to insert 8 ea. 1/2 inch PVC risers through the bench to allow insertion and removal of the tomato cages. Each pipe is the height of the container and has a slipon cap at the bottom. I drilled aeration holes into each riser to aid aeration and prevent standing water. The caps prevent the ends of the cages from puncturing the bottom of the container. Once two cages are inserted and wire tied together, they are very stable, even with a second cage mounted upside down on top.

HINT: put the container on it's side to insert the bench, otherwise all the risers will fall out first!

earthtainer 3

Other mods in this picture include painting the lid to retard UV degradation, using a trash compactor bag (thicker plastic) to create the cover and to provide shade for the side of the SWC, and using a sealed drinking straw as a water level indicator.

I am harvesting pounds of cherry tomatoes from the SWC's. Unfortunately, we are in a quarantine zone for the oriental fruit fly and cannot share the bounty. I have the solar assist dehydrator going almost full time.

Hope this helps,

Rick


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RE: My latest SWC prototype

Follow up on my variable orifice SWC;

It rained and got humid today, never got as hot as it should so the moisture evaporation and demand on my pot was not as great as hoped for, even in the greenhouse. However, the mix is still appreciabley even drier with the higher humidity and lower temp.

I think the experiment is a success on the surface, but will wait till morning light to do anything more.

Rick,
I was wondering if you tried moving your orifice valve witha full load of wet mix, and if you found it very difficult to open/close? I noticed your movement lever was below the actual orifice cover and wondered if you thought that effected the ability to completely close the hole to the potting mix?

thanks

d


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RE: My latest SWC prototype

Great modifications, Rick!
This Thread is very informative.
I can't wait for the final harvest/season reflections.

Josh


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RE: My latest SWC prototype

d,

I just tried to move the flap and it is immovable (for me). I used only potting mix over the flap so it would not be trying to move laterally through pine bark. The flap is on top of the aeration bench. It did work when I first loaded the SWC but I suspect the area of the orifice is now rootbound. Oh well, we will see what happened post mortem.

If I were to design a variable flow bucket SWC, I think I would use one small orifice soil wick and some rope wicks. One or two push rods or rotating levers would elevate (and lower) the ends of the rope wicks in the reservoir as desired. There are challenges to maintaining a variable orifice.

YMMV

Rick


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RE: My latest SWC prototype

Trying to move that valve thru the dirt and mud is tough.

I was able to move my orifice valve a few times and then it failed. So I suspended my moisture test and did a minor redesign of the orifice valve surfaces.

Turns out that there were a lot of rough spots on the surfaces caused by my lack of attention to detail.

So I put a clean new false plastic bottom over the old 5 gallon bucket bottom. It tested better opening and closing.

So now back to testing to make the bucket sufficienttly wet and then dry by changing the oriface size.

Hope I dont have to go to a worm gear; dont make me do that!

d.


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RE: My latest SWC prototype

I have opened/closed the new valve every 12 hours for 5 days. It works without jamming.

As far as controlling moisture, for "wet" mix; the 12 sq in sliding valve between the wicking baskedt and the potting mix is open, the lid is on the container, and the "wicking sock" is buried inside the soil mix--in 12 hours the mix gets kinda moist starting from pretty dry. some plants might need a little top watering.

For 'dry' the valve is closed, the lid is off the potting mix container and the "wicking sock" hangs out of the container about 8". Teh mix gets dry enough in 12 hours that I would say most plants would be drooping.

So I think one can adjust moisture adequetly with the three combined techniques without disturbing the plant or the mix. That was my goal.

But it does require 1. the "wicking sock", 2. covering and uncovering the top of the potting mix, and 3.covering/ uncovering the 12 sq in opening between the potting mix and the wicking basket - this area had to be made pretty smooth so that the sliding valve did not hang up on any rough spots. I accomplshed that with a plastic false bottom covering all the tie wraps and everything except the wicking basket hole. Its stil a little tough with the dirt/mud and bark.

but one would only adjust a few times hopefully, during the season.

Now for more info on potting mix wickablity and anything that wicks.

D


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