Many self-watering planters use the soil itself as a wicking material. The soil is contained within a tube in the center of the planter. The tube extends from the bottom of the soil basket in the planter, into the water reservoir. This tube is designed with holes that allow the soil and water in the reservoir to mix. Water is absorbed into the soil through these holes.
So, could I do the same with wicking beds? Could I just leave folds of the landscape fabric on top of the rubble hanging down into the water reservoir and then fill it with a peat based planting mix? (The peat would counteract the alkalinity of the concrete and improve wicking.)
Please may you explain what you mean by "leaving the folds of the landscape fabric on top of the rubble and into the water reservoir. This is what I am imagining:
I think that would be fine; however, if the flaps are horizontal, it will deflect some water from entering and stop some from rising- I think...
I can't figure out whether your diagram matches what I am thinking about or not, so I am attaching my plan. See what you think.
The article you linked to shows wood chips being used both for in ground beds and raised beds. In fact, they don't even mention gravel. Wouldn't wood chips get all slimy and anaerobic, and generate lots of methane and alcohol that would kill off the plants? If not, that would be wonderful, as I can get plenty of wood chips free.
Why do you want to build a wicking bed? What is the intended purpose of making the dip/folds in the plastic?
What function is the bed supposed to carry out? Depending on what it is going to be used for and its overall purpose, there might be another alternative better suited for your environment and specific situation. Please may you elaborate.
I'm not sure what would happen with the little dip. The best guess I can think of is that it would act kinda like a straw, the moisture gradient is easier to get in those little pockets.
The reason I included the little dips is because I don't have the money for gravel. I was thinking that I could fill the reservoir section with large concrete rubble, which would not wick as well as gravel. So the dips would act like wicks for the rest of the bed. I thought the wicking containers might be precedent for this. One of the wicking container sites explained that if the whole bulk of soil was wicking up water, the pot would get waterlogged. Just having a small pot or pipe full of soil or peat, wicking water for the whole large pot, was the way to get exactly the right amount of water.
Here is a link about building this kind of wicking container. Basically, I am wondering if I could replicate that on a bed scale.
The overall, master plan for the wicking beds: We need to keep our foundation dry, but I don't want to waste a beautiful sunny brick wall. So the beds should allow for planting without wetting down the soil by the foundation. The beds will also catch, partially capture, slow, and redirect the flow of water from gutters. Some of the beds will probably be insulated and topped with a cold frame, for early seed starting in the warm microclimate of the wall. About ten feet up, a shade structure on posts will hold grapes, shading most of the wall (but not the beds) in the summer while letting in the winter sun.
Thanks for your replies!
Likewise, I think your plan should work because tinier holes will allow the water to travel higher, and your spacing of the little dips might determine how much water is brought up from the ground at a time. Ooh, I forgot to to think of this earlier:
See how the water travels up the concrete wall? Concrete is not entirely solid, so maybe crushing it so pieces is not entirely necessary... That is also why concrete breaks from freeze-thaw action, the water soaks in through the little pores and expands. A possible experiment that could be conducted would be to see how crushing/splitting the concrete affects the capillary action compared to how leaving the concrete in larger chunks works.
If there are any demolitions going on nearby, asking them for some of the concrete may be a way of obtaining it for free. Also, freecycle, Craigslist Curb Alerts, and Craigslist Free Stuff are ways to find things for free. I did a quick search for concrete with free stuff, and there are some people in Denver, CO with free concrete that you can get (in the third link). One cool trick: If This Then That can be used to say, "if a new post appears on craigslist, then, alert me about it,"
I think the grapes idea is spot on! Not to mention, very tasty.
1. old carpet instead of geofabric
2. plastic pallets to form a void
3. charcoal above and around the pallets
The carpets and pallets are free and I make the charcoal. The oldest beds were built two years ago. I have never detected any off smell in the water that drains from the bed in heavy rain or when overfilled.
I wrap the pallets in carpet to protect the liner (standard builders waterproofing membrane) and to prevent sedimentation of the void. The carpet seems to be an effective wicking medium.
The brick wall could be one side of the wicking bed. Line this, the floor and the other three walls with carpet. Fix the liner over the carpet and place a second layer of carpet on top and up the sides of the liner. Place the pallets . Lay more carpet over the pallets and tuck down the sides to form the pits shown in Gilbert's sketch. Add a layer of charcoal over the pallets and down the sides. You could add more carpet over the charcoal or fold over the sides or simply fill the bed with soil/compost. A drain from PVC pipe with drilled holes also wrapped in carpet can be placed horizontally in the charcoal layer. A vertical fill pipe is placed in one corner through to the base of the pallets.
I can taste the grapes already.
The part that hangs into the resoivar cab be restricted into a bottomless bucket or pvc pipe or perhaps with zipties.