Self-watering SIP Sub-irrigated Raised Bed Construction (How to Build)

Very interesting. Then he said no compost or manure in the growing mix!!

+1 That's the simplest design I've seen for a SFG size wicking box. And, he has the experience to support its effectiveness.

sanderson wrote:Very interesting.  Then he said no compost or manure in the growing mix!!

I was curious about that statement, too.  He seems to have an an aversion to compost in general, but I followed the link to his site to see if he explains why he doesn't like compost, and found this in a text article on building his raised beds (http://www.albopepper.com/SIP-raised-bed.php):

has55, would you please post the link for those of us who can't get the vids to work on their stupid li'l tablets?

www.youtube.com/watch?v=Lp9Jdyno9hI

Well, for some reason, the quote from Al's site didn't get saved with my last post.  I'll try again.

This is his explanation of why he doesn't like to use compost in his potting mix.

"Yeah, but. Yeah but!" I've gotten reports of people who have used 1/3 manure, 1/3 peat moss & 1/3 vermiculite (Mel's Mix) with great success in SIP containers. This might work for some people. This is your bed and you can try what you want. But manures and bagged composts may have very small particles which could fill up your pore spaces. They also have a very broad range of NPK values and using them may be hard to predict. So I don't recommend it to others. Instead, I stick with the guidelines that EarthBOX recommends.


I'm not sure I don't agree.  I'm using MM in my sub-irrigating containers for the first time this year, and the plants I have growing in them are not doing well.  With the mix I used last year, you could tell the water was traversing the mix, because (except on very hot days) the surface was always damp.  With the MM, the tops are always dry, except when it rains.  I dug down into one of them that no longer had a plant in it, and it was dry in the top 2 inches, then I started to find damp mix beyond that, but not very damp.  I've also noticed that water consumption from the reservoirs is significantly lower this year, which may mean less water getting to the plants.

I have neighbors growing the same plants in the same containers, and theirs are doing great - just like mine did last year.  So that probably eliminates environmental issues, such as the heavy rains we got earlier in the growing season.

Whereas the MM is doing fabulously in my raised beds, and I will definitely continue using it there, I'll probably go back to the mix I used in previous years in my containers.

I didn't have luck with MM in the Earthboxes either. It didn't seem to wick up the water. I supposed it would work with tomatoes & such where the roots go deep once those plants are established and large, but they'd have to be watered from the top for a while. Eventually the system of not having to water so often would kick in.

Although I've read on the forum that some have great luck with MM in their Earthboxes.

CC

I wonder if the problem might be partly the wick, or other parts of your system, CC. The roots of my tomato plants sometimes completely pack every inch of my 5-gallon containers with MM, which I take as a sign that the plants are getting value from sending out so many roots -- water, nutrition, aeration, etc. The single self-watering container I built has MM in it and the roots pervade the soil very well in it too.

I've seen some SWC's with pretty small wicks. And because MM can dry out and lose its ability to absorb water properly, I take it for granted that even with great soil and/or a SWC container, I'll have to give MM some extra watering.

On the other hand, the richness of MM means I will have to do less fertilizing and will have an inherently good soil instead of the largely inert stuff and high-fertilization rate that so many others recommend for containers.

If anything, I've pondered whether the thing MM in containers could use is a bit more vermiculite, as water retention is so vital in my endlessly hot and dry growing seasons.

Marc Iverson wrote:
On the other hand, the richness of MM means I will have to do less fertilizing and will have an inherently good soil instead of the largely inert stuff and high-fertilization rate that so many others recommend for containers.

If anything, I've pondered whether the thing MM in containers could use is a bit more vermiculite, as water retention is so vital in my endlessly hot and dry growing seasons.

I am having one heck of a problem keeping the MM moist.  Eventually I will add drip irrigation which should help.  I do heavily mulch.  But with hand watering using a wand, it takes forever to get the mulch wet enough to allow the water to enter the MM.  Then by the next day it is completely dry again.  I still have 160 square feet of beds with original garden soil that I have added some vermiculite.  I only have to water the old style beds about once a week.  Any bed with MM that is intensely planted has to be watered every day.  It will be bone dry the next day.

So I am seriously thinking about making a bed like the video.  Or else finding how to make MM that will retain some moisture for a longer period of time.  I think it is the peat moss.  I am thinking about trying coir.  Does anyone use it in MM and if so, exactly what variety of coir.  There are so many different brands advertised.

I'm enjoying everyone's feedback on their experience with wicking boxes. I haven't tried small boxes.

Kay and I  built SFG wicking boxes using different designs, and we had good results using MM in them.

Walshevak's boxes
https://squarefoot.forumotion.com/t5716-experiment-to-deal-with-pure-sand-and-high-water-bills

Boffer's box
https://squarefoot.forumotion.com/t3068-sfg-wicking-boxes

In my box, the top inch or two stayed on the dry side, and required watering until the seeds or transplants got established.

The size of the plants' root structure depended on the type of plant.  Some, like lettuce, had root depths to 3-4 inches, while tomato roots went down into the wicking baskets.

Marc Iverson wrote:If anything, I've pondered whether the thing MM in containers could use is a bit more vermiculite, as water retention is so vital in my endlessly hot and dry growing seasons.

I was wondering the same thing, Marc.  Perhaps MM can be amended slightly to optimize it better for sub-irrigation techniques.  The mix I used before definitely worked better for this type of irrigation, it all stayed moist right to the surface most of the time.  I'm not sure exactly why, but I agree it may have something to do with a soil's ability to absorb and retain water.

boffer wrote:Boffer's box
https://squarefoot.forumotion.com/t3068-sfg-wicking-boxes

boffer, I really like your version of a wicking box.  It's slick and solid, and looks easy to maintain.  This could be the solution to my box irrigation problem I've been playing with.  Thanks for sharing that.

I forget if I mentioned it in my wicking box thread, but I recommend using something heavier than 6 mil plastic for the box liner.  

Because it was an experiment, I did it on the cheap.  For the tub box, first I silicone caulked all the joints; then I lined the box with some torch-down roofing material; then I used 6 mil plastic as a liner on top of that.  I still got a small leak.

If I were to build another one, I'd spring for PVC 30 or 40 mil pond or shower pan liner.  I've read where some folks have used EPDM roofing membrane, but it's primary ingredients are ethylene and propylene. I haven't looked to see if they would leach into the water, or if they would be a hazard.

Have fun!

I've moved into the house that has the wicking boxes now.  Only 1 of the wicking boxes is in use this year, planted with sweet potatoes.  The other 4 are so full of grass and weeds that I'm going to pull everything out when the weather cools off and redo them.  I need to make them tabletops.  I just can't get down to tend them.  However, the one that is in use is doing fine and still wicking. 

 Based on another site I follow, they use more peat in their mix than we do.  The claim is the peat is what enhances the wicking.

Kay