Wicking Bed in the Hoophouse

In the past couple of years I have only grown in the middle of my hoop house because that was the easiest place to reach.  I am planning on digging it down 10 to 12 inches this year to allow for more head space and growing space for the tomatoes.  In addition I wanted to add some thermal mass to the edges to keep heat in and block out wind.


In building the retaining walls for the earth mound that was to be at the the edges I realized that I could put a raise bed in there.  So I dug it down and used this opportunity to try a wicking bed.

Caveboy in the 2014 hoop house in May. Except for this hydro bed, all the growing has been in the center.  

What is a wicking bed?
A wicking bed is a method of planting which allows for maximum water usage when growing in soil.  It is more efficient even than hydroponics, assuming one actually replaces the water in their hydro system as often as recommended.

How does it work?
One of the biggest problems with growing in soil is water loss.  Water is lost into the air when watering from the surface, and water is lost into the ground as well.  Mulch can help prevent water loss into the air, especially if you use a drip system.

Wicking beds address both of these issues by watering from below the bed from a reservoir.  The only way for the water to go is up, into the soil where the plants roots are.

A typical layout looks like this:

http://www.earthanedge.com/earthan-beds-how-they-go-together/
(I don't  have a fish pump.  I just fill it with water)

The reservoir underneath is usually filled with small gravel or sand which move water upward through capillary action.  Between the soil and the reservoir there is usually a barrier of some sort to keep soil and roots from getting down into the gravel, but it isn't always used.

As the soil above dries, the moisture is drawn up from the reservoir.  In this way the plant regulates soil moisture to whatever level it prefers.

You can't over-water these beds because there is a drain at the top of the reservoir.  Once it is full, it is full.

Instead of piling soil here, I decided to dig down several inches: maybe 3 or 4 to set the reservoir in ground a bit.  In order to use runoff from the hoophouse, and overspill from the wicking bed I dug a shallow ditch to direct excess water into one of the swales in my berry patch.

North edge of the hoop house

Digging in clay is fun. 

Reservoir Liner
After digging out and leveling the reservoir, I lined it with landscaping plastic.  I placed some old roofing tar paper I had in my shed below it to prevent puncture from rocks and roots below.

Tar Paper

Staple it up

Adding water to check level, and troubleshoot the drain.

Reservoir Medium
The next step was to add the gravel.  I used the pea gravel from last year's hydro set up.  I'll be using river rock this year for hydro because it is easier to clean.  The PVC tube sticking out is  for watering. It connects loosely to another 2" pipe and then a 1" pipe to disperse the water slowly into the gravel.

I will only grow on one edge, so I have indented there for more soil contact during initial watering. 

Happy berries

Dividing Soil From Reservoir
Then I laid the weed guard across the top and stapled it to the board that defines the inner edge of the bed.

Weed guard covering the bed and the watering hole

Peat Moss
For good transmission of moisture upwards, soil high in organics is best.  I have clay so I have amended the soil a little.  First to make sure moisture is transferred easily I added a layer of peat moss to the top of the division.

A thin layer of peat moss

Soil Mixture
As I mentioned, my soil isn't the greatest.  I won't be fertilizing this bed for a couple of years so I added some mulch and chicken coup mix (complete with feathers and mummified mice) and hoed them together with soil I dug up from the middle of the hoop house.

Poop. Dirt. Mice.

With each layer I added a little more peat moss to ensure good moisture transmission.

All full! 

Get it Wet!
The last two steps are to make sure the entire bed is wet to start the capillary action and to cover with mulch.  I plan on growing peppers in here. If I'd had this bed before, they'd already be growing.

 The next step is to actually plant some peppers.  I'll let you all know how that goes.


I'll write about the berry patch project soon, but I can tell that one of the swales is working nicely.  I've taken the other out to try to figure out why it wasn't holding water.

Water stored below the mulch in the swale between berries and rhubarb.  Like a wicking bed, this water will move into the planting mound as it dries.