Growing Strawberries in a Self Irrigating Gutter (SIG).

self irrigating srawberry container

I got this idea from Larry Hall, who made a video showing how he uses gutters as self watering containers. In the first part of the video Larry shows how to use a gutter to supply water to a row of pots. In the second part he shows a two gutter strawberry growing system. I decided to build Hall’s self-irrigating gutter (let’s call it a SIG) to grow strawberries. Here’s how I did it:

With some scrap wood I made a support system for the two gutters–one gutter holds water and the other holds soil. I sealed the ends of the two gutters with silicon putty and secured the gutters to the wooden support with screws.

float valve in self irrigating gutter system

Next came my first trip to a hydroponics shop (there’s one on every corner in Los Angeles), to get a float valve. The float valve, similar to the one in your toilet, automatically fills the lower gutter with water as needed. I tried to fit the float valve through the end of the gutter but this kind of DIY bulkhead fitting is difficult to pull off. I ended up mounting the float valve above the gutter with a pipe strap, as you can see in the photo above. I cut the upper gutter around 10 inches shorter than the lower one so that I could access and maintain the float valve.

mesh cup

The second item I picked up at the hydroponics shop was a bunch of 3 inch mesh pots. These hang down into the lower gutter and wick water up into the soil. I cut circular holes in the upper gutter using a hole saw, and fit the mesh cups into the holes.

Next I filled the upper gutter with potting mix (note that with self watering containers you have to use potting mix, not regular soil). And all self watering containers need mulch of some kind–I just happened to have a roll of vinyl billboard material that my neighbor Ray gave me. I stapled the vinyl to the wooden gutter support and stretched it over the top of the soil. I cut holes and planted my strawberries about 8 inches apart.

rain barrel

Rain barrel. The white pipe on the left is an overflow pipe that drains to the street.

The float valve is connected to a rainwater barrel. You can read more about how this barrel is constructed in one of our older posts. Since SIGs need to be watered even when it’s raining, this is a perfect use for a rain barrel. I will have to fill the barrel with municipal water during our dry season.

There’s a lot of plastic here, specifically PVC, which is an environmental and health disaster. I have two questions–how much PVC is leached into the growing medium and how much of it would be taken up into the fruit? I don’t have an answer to either. If you know of science-based information (i.e. not Livestrong articles) on PVC and growing food please leave a link. Generally, plants do not take up toxins into fruit so I’m not losing any sleep thinking about eating a few strawberries grown in my small PVC SIG. I might think twice about eating greens grown in PVC.

The other issue is the use of peat moss as the growing medium. Peat moss is unsustainably harvested (see Horticulture professor Linda Chalker-Scott’s article on this). Coconut coir, in my experience works great, but not in self watering containers. If you know of a peat moss alternative for self-watering containers, please comment.

There might also be mosquito problems with the standing water in the lower gutter. This could be countered with a mosquito dunk.

strawberries in gutter SIPAdvantages
I can now grow food in an otherwise useless space–the top retaining wall in our front yard (we live on a hill). I can also, finally, make good use of my rain barrel. I was also able to recycle a bunch of scrap wood and some billboard material. And, unlike hydroponics, no electricity or liquid fertilizers are needed. If this system works out I’m eying the top of our garage for more SIGs (our garage is at street level below the house–we look down on it from our front porch).

I think there’s also an opportunity for an entrepreneur to make a non-PVC version this gadget out of food grade material such as HDPE. With a custom design you could also enlarge the upper, soil container gutter as well as creating a sealed mosquito proof lower container. But you would have to sort out who owns the patent on self-watering containers.

And many thanks to Larry Hall for sharing this cool idea!

UPDATE 4/30/2013: One side of the strawberry gutter sprung a leak due to a poor seal on the end of the gutter. I was able to fix it. One thought about the design is that you should leave both ends open and the gutter ends accessible so that you can make repairs. And make sure to use a sealant appropriate for gutters.

Growing Your Own Food is Like Printing Your Own Money: Ron Finley’s TED Talk

Please take a moment and watch gangster/guerrilla gardener Ron Finley’s inspiring Ted talk. I first heard about Ron after he got busted for planting a vegetable garden in what used to be a weed strewn parkway. He’s gone on to plant many more gardens around Los Angeles.

The end of this talk really hit home for me, “Don’t call me if you want to sit around and have meetings. If you want to meet with me come to the garden with your shovel so we can plant some s**t.”


Matt’s Wild Cherry Tomato

Matt's Wild Cherry

Matt’s Wild Cherry image from Johnny’s Select Seeds.

Permaculturalist Paul Wheaton was in our neck of the woods this weekend to give a couple of lectures. In his talk on “Irrigation Free Foodscapes” he mentioned a variety of tomato called “Matt’s Wild Cherry” that, as the name implies, is a wild-type tomato that grows without supplemental irrigation.

Many avid vegetable gardeners have probably had the experience of tomatoes that reseed and grow without care. In my experience these hardy rogue tomatoes are invariably on the cherry side of the tomato size spectrum. This makes sense as the tomato’s wild ancestor is much smaller than modern beefsteak varieties.

Matt’s Wild Cherry was obtained in Hidalgo, Mexico by Teresa Arellanos de Mena, a friend of  agronomy professors, Dr. Laura Merrick and Dr. Matt Liebman. Johnny’s and other sources describe it as a small current sized tomato that readily reseeds.

Johnny’s Select Seeds carries it, and I’m considering giving it a try to supplement the tomatoes that reseed themselves in our garden. Let us know in the comments if you’ve tried Matt’s Wild Cherry or have tried any other wild-type tomatoes.

How To Manage a Compost Pile Using Temperature

compost temperature chart

I’ve always been confused about when to turn a compost pile. Some people suggest lots of turning while others don’t turn at all. I built a pile in December using a technique I learned from Will Bakx, soil scientist and operations manager of Sonoma Compost. Bakx recommends keeping the pile between 131° F (55° C) and 163°F (72°C) for a period of 15 days. The only time you turn is when the pile starts to dip below 131° F or to prevent the pile from going above 163°F.

The technique is simple–all you do is take the temperature once a day with a compost thermometer and write down the result on a calendar. The graph above is the result that I got from a pile made out of horse bedding, chicken manure from our hens, plant materials, straw and brew waste from a local brewery.

The red area on the chart is the thermophilic temperature range (135° -160° Fahrenheit). The dip you see at day 15 is the one time I turned the pile so that I could keep it in the thermophilic range. Using temperature as a clue to when to turn the pile has a number of advantages:

  • You can make sure that the pile does not get too hot. Above 160° F  you start to kill off the thermophilic bacteria that decompose your pile. To decrease temperature you turn and add more carbon material and water.
  • Washington State University recommends subjecting all of the pile to temperatures above 150° F to kill potential pathogens. I’m fairly certain that, with the turn I did at day 14, all of the pile got up to 150°F.
  • Weed seeds are killed above 130°F–another reason to watch temperature.
  • Failing to get high temperatures can be an indication of too much carbon or a lack of water. To correct, add more nitrogen and water and turn.
  • A loss of temperature could indicate that the pile is going anaerobic. The solution is to add more carbon material and turn.

Once the pile has had 15 complete days over 131° F you just let it sit. Compost is done when it is dark, smells like earth and you can’t recognize the original ingredients. It will likely be several months before it’s ready to use. I’ve found that I need to turn the pile periodically and add water after the initial thermophilic period due to our dry climate.

The mass of the pile is a factor as well–I’ve found that it needs to be a minimum of one cubic yard of material to start with. So I save and scavenge materials that I can use to build a pile all at once. The small trickle of kitchen scraps we generate each day goes into our worm bin.

Despite the geekery with using a compost thermometer, I’ve found that this method saves labor. Back breaking turning only happens when it’s necessary.