6 Things to Know About Wicking Garden Beds
Want to water more efficiently, grow food in any location, and reduce wasted effort in the garden? Consider wicking garden beds…
If you want to streamline your gardening efforts, and reduce the amount of time you spend weeding and watering, wicking garden beds can be a great addition to your garden – especially for those gardening in dry climates or urban areas. Wicking beds are particularly helpful for urban gardeners because they can be placed on any surface – even a concrete patio or a rooftop – and you don’t need a large yard with great garden soil.
So what is a wicking garden bed, exactly?
It is a raised garden bed with a built-in lining that holds a reservoir of water in the bottom. The lining is typically filled with a porous medium that helps “wick” water to the soil on top, where your plants are planted. This creates a very efficient self-watering system that requires little maintenance, and uses less water than most traditional irrigation systems. This system is also excellent for gardeners with limited strength or mobility, as it eliminates lugging heavy water containers around, and the high beds can be built to reduce or eliminate stooping and bending.
If you’re ready to take your irrigation (and your garden) to the next level, Ray over at UrbanFarm.org wrote a helpful series on wicking garden beds. Here are some of the highlights:
Some Pros and Cons of Wicking Garden Beds
- The bed is 2-feet high making gardening easier.
- The constant supply of moisture at the root level and overflow tube prevent over-watering.
- The bed is drier at the surface so weeds cannot germinate.
- Uses 40-50% less water than traditional garden beds
- I can leave for a couple of weeks without worry because I water less often.
- Can be constructed on any surface
- Minimal loss of soil amendments because they are not being washed away by top watering
- Salt and minerals are not added to the planting medium from top watering
- Difficult for tree roots and grass to penetrate the liner
- I am growing nutrient rich food for my family.
- More difficult to construct than a traditional raised bed
- More expensive to build than traditional raised beds
- Some change in the way you maintain your raised bed
- Requirement to drain and refill twice a year.
6 More Things to Consider When Building a Wicking Garden Bed
1.) One size does not fit all
The size of the garden bed is important and highly personal. Consideration must be given to the person tending the garden. When planning a raised garden, a good rule of thumb is: it shouldn’t be any wider than twice the arm reach of the shortest person working the bed. In other words – can the shortest person reach the middle comfortably?
Another consideration is the height of the garden. Build the bed to a height that is comfortable for the shortest person working the garden. A friend of mine built a wicking garden bed 3 feet tall because she had back issues, and that worked great for her. She filled the bottom 18 inches of the bed with sand before installing the liner. Additional thoughts are how many people are being fed from the garden, how close to the house should the garden be, and how close is the water supply?
2.) Taking a compass bearing
I was asked to build a raised garden bed with a friend. She had decided on the orientation for purely aesthetic reasons based on the view from the house. It wasn’t until months later, during the summer heat, we realized the bed was getting full sun along its eight-foot length. She was having had a difficult time keeping plants alive, especially along the south and west sides. This was right after I discovered wicking beds, so we converted it to a wicking bed thinking the addition of a reservoir would help solve the heat issue. It wasn’t until the following summer we discovered this did not resolve the issue enough. The garden still performed poorly, not because of the summer heat we realized, but due to the bed’s orientation.
Most experts believe the best way to orient garden rows and raised beds in the Northern hemisphere is north to south— with short sides of the garden facing the north/south. This gives the best sun exposure, allows for ample air circulation, and reduces the heat gain to the framing material. The bed we built was oriented east/west; the better orientation should have been… north/south.
3.) Going around the block a few times
Stone blocks do not make a good frame for a garden bed, at least not in the southwest desert. They can add an additional 8” or so to each side of the garden bed, which reduces the actual planting area and can make the center more difficult to reach. On top of that, stone and cinder blocks are a heat sink material – a true negative in hotter gardening zones. They capture the heat of the day and continue to radiate it during the cooler evening hours. The garden does not have an opportunity to cool down using these materials. On the plus side, I have to admit they are comfortable to sit on while tending the garden.
After several years of using them around my yard and for my raised beds, my current garden beds are made from 2 X 12 wood planks…
4.) Keeping my cool
In an effort to keep the planting medium appropriately cool, I experimented with 3/8” foam insulation between the wooden frame and the pond liner in on of my wicking beds. And yet when I started recording temperatures in the two equally sized, side-by-side gardens, I discovered the insulation actually held the heat in the planting medium instead of mitigating the heat gain. I believe foam insulation would be a great option in the colder regions, but not for hot zones like mine.
5.) To rock or not to rock
When I built my first wicking bed, I based my design on the beds built by the person who introduced me to the concept. She originally used large river rock in her reservoirs. However, she learned such large rocks did not allow water to move up to the planting medium. So instead I used ¼” river rock which worked well.
After building these beds, I found an article written by Collin Austin stating the use of a rock filled reservoir was not his design, and in fact he indicated the planting medium itself should be part of the reservoir. So, in my next version (Wicking Beds 2.0) built at my friend’s house, we experimented by using a different fill pipe and put the planting medium all the way to the bottom of the garden bed. The wicking properties of this design was excellent.
6.) One pipe is not like the other
Since the wicking bed 2.0 garden was working so well, I changed the internal structure of one of my personal beds to match. We found the 1 ¼” PVC pipe previously used didn’t fill the reservoir quickly, so I changed to the Bend-A-Drain 4” polypropylene flexible drain pipe used in 2.0. It was easy to see how the wider pipe allowed filling the reservoir easier and more efficiently, and we appreciated how it became another way to view the reservoir water level.
There are a number of ways to build your own wicking garden bed. You can use different materials for the container and reservoir, and different liners and wicking mediums. Watch this video for an easy way to build your own wicking garden bed using recycled materials.