Thursday, July 9, 2009

A Little Sub-Irrigation Anyone?

Ah...sun! I sit here in the garden with my laptop, enjoying the first sunny day we've had in 3 weeks. The good news is that the plants survived last night's cold. I'm not sure if there was any frost as I had blogged about previously, but I can see a difference already in the garden...the tomatoes are perking up and the bees are out.

I thought I would take this opportunity to introduce one of my new gardening 'experiments'. After my success with starting plants from seed, I ended up with a lot of left over tomato and pepper plants. I gave a lot away to friends, but didn't have the heart to compost the remaining ones without giving them a chance to produce. I considered replanting in pots, but came across a more intriguing idea: the sub-irrigated planter, more commonly known as the "self-watering container".

The sub-irrigated planter, or SIP, seems to have a bit of a grassroots following around the web. It is basically yet another way of growing your own produce when you are short of space. It is supposed to be very efficient, using less water than a traditional garden. In urban areas, it would be great for people without any "land" to grow on, and is ideal for growing on a rooftop, balcony, or pavement.

Here is what my SIP looks like after planting:

The concept is fairly simple. A SIP is basically a planting container that uses hydroponic science, allowing you to water from the bottom up. The container does not have any drainage holes as the water is collected at the bottom in a reservoir and is 'wicked' up to the top to provide moisture and nutrients. You can purchase a self-watering container known commercially as the "Earthbox" . It is also fairly easy to make your own and there are numerous sites with instructions on how to do it.

I first stumbled across this method while researching urban gardening on the web. I found a great site for the Montreal rooftop garden project, which has taken the whole concept of hydroponics or sub-irrigation to show how easy it is to grow a garden without soil using easy to find, inexpensive materials.

The whole method they use, with detailed instructions on how to make a SIP planter out of buckets, barrels and other common materials can be found here:

Another great site with step-by-step instructions on how to create a 2-bucket SIP is the Chigaco Green Roof Growers.

I decided to use a food-grade bucket in making my SIP. A lot of other people out there seem to be using rubbermaid storage tubs. I am always concerned about what is leaching into my soil. A 'food-grade' bucket sounds safer than the plastic used in a storage bin. Of course, using plastic anything is probably a bad idea. But, I will put my niggling worries aside for now. (You can check out this link from the green roof growers site for arguments for/against using plastic in the garden and what types of plastic are considered safe ). Once I started out, my biggest problem was actually finding a enough buckets. I tried all the local grocery stores and only managed to scrounge 2 medium sized buckets from superstore- not the 5 gallon ones needed for tomatoes. I even checked out Kijiji and to my surprise someone was selling them, but they were located in Yarmouth area...a little too far away. With my options quickly running out, I sent my husband up to my local make your own wine store, the Noble Grape, to purchase the food grade buckets used in the wine making process. He came back with two buckets. But it turns out those buckets were a little pricey - $20 each! If I had gone myself, I probably would have given up. Oh well, i'll be all set if I ever decide to change from vegetable gardening to wine making.

With only 2 buckets and using the traditional instructions for making a SIP, I would only end up 1 planter. Luckily, I found some alternate instructions to make a SIP using only one bucket - hopefully this method will work as well!:

I basically followed these steps with a couple of changes. I wanted to use supplies I already had on hand as the bucket purchase basically broke my SIP budget in one foul swoop (I was hoping to get them for free after all). In lieu of the window screen, I used a coir garden "mat" that is commonly used in hanging planters. I had this left over from a differerent project a year or two ago and purchased it originally from Halifax Seed. I think this is a good substitute as it is air/water permeable like the screen, but made out of coconut fibres, eventually compostable, and had no glues or additives. For the watering tube, I used a scrap of copper piping.

Here is a picture of what it looked like pre-planting. The middle 'soil-wick' I used was fashioned out of a cut off 2 L milk container with holes punched all over it.

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