About us

Campus Crops is a student run urban gardening initiative at McGill University's downtown campus. We want to grow food on campus, by students, for students. We have been running garden behind the School of Environment building at 3534 University since 2007. In 2009 we started a terrace garden behind the James Administration building. We're really excited to keep improving these two spaces, and need lots of helping hands for the summer ahead! Get in touch and get gardening!

Thursday, June 6, 2013

Step by step how to make your own self-watering container (plastic reservoir method) with pictures!

Because it's good to know, here's one of the multiple ways you can make your own self-watering container. This method has the advantage of being both cheap and homemade, yet doesn't make the container as heavy as with the rock reservoir method.

What's a self-watering container, you ask? Well, self-watering containers do not literally water themselves, but they do help water plants less often.
The principle is quite simple: water is poured down a pipe directly in a water reservoir, sitting under the soil. There, a wick takes the water from the reservoir to the soil. As the plant(s) use the water made available to them in the soil, the wick takes more water from the reservoir to the root zone of the plant(s). In some way, the plants water themselves (but they don't, also, you know).
Source: http://cache.gawkerassets.com/assets/images/lifehacker/2009/03/2009-03-30_113406.png

You'll need:

- a plastic container that will offer enough space for a decent-sized water reservoir and the roots of your plant, often at least 30 cm in width, length and depth for vegetable crops; check up the spacing requirement and soil depth needed for the plant(s) you want to grow in your container if you're not sure what size you need
- a sealant (maybe)
- plastic boards
- PVC pipe, about 1 inch diameter
- geotextile, as cheap as you can get
- perlite
- good soil
- compost (maybe)
- something that cuts
- a saw
- a drill or something to pierce a hole through hard plastic

The plastic we use for this model is Coroplast, which you can probably find at your local hardware store, or at your local deputy/MP/whatever office not long after an election period (or in the streets during the election period, but this is not usually recommended and Campus Crops doesn't suggest you do it either oh heeeellll noo!). Other types of plastic can work too, but they need to be both quite rigid, while being soft enough so you can cut them quite easily. 

PVC pipes, geotextile, perlite and soil can all be bought at a hardware store too (don't ask your MP for those, though).

Anywho, let's unleash them pictures.


1) No matter what type of container you use, make sure it's watertight near the bottom, and drill an overflow hole anywhere between 7-15 cm from the bottom of the container, depending on the size of said container (you want as much soil as possible in there, but too much soil for too little water won't help either). If your container is not already watertight, we suggest using this sealant, or any other sealant that works in water, works with plastic, and is not toxic. Extra points if the product description mentions that it's safe for sealing aquariums (aquaria? whatever, if it's good for the fish, it won't poison your vegetables).

2) Cut your plastic into strips that will fit lengthwise and widthwise. For the width of the strips, see step 3. Calculate you'll need a strip every 20-25 cm in both directions (lengthwise and widthwise) at the bottom of your container. Cut slits into the strips where they will intersect with other strips.

3) Arrange the strips into a grid pattern at the bottom of your container. An important thing about the width of the strips is that the grid must be about 1 inch (2.5 cm) above the overflow hole you pierced in your container. This is to ensure a good airflow in the soil and the reservoir even when the latter is full of water. Otherwise, expect anaerobic conditions, pathogens, diseases, death, and the four horsemen of the apocalypse.

Fits perfectly!

4) Cut another piece of plastic to cover the bottom of your container. Put it over the grid. Voilà! That's your reservoir! 

Some people like to leave the corners uncovered, either to use them at wick (more about this later), or to put the PVC pipe. If you don't want to do that, make sure you cut out a hole somewhere to insert your pipe.

Fits perfectly!
5) Saw your PVC pipe. Make it long enough to stick out of the container by a few inches. Saw an end at an angle, otherwise it may lay flat on the bottom of the container and water will stay stuck in the pipe instead of going into the reservoir. Insert the pipe in a corner or along one side of your container.

6) Make a wick. A wick is something that will get the water from the reservoir to the soil (by capillary action), to make it accessible to the plant. Without a wick, the water would just sit at the bottom of the container and your tomatoes would be like "Meh."

A wick must be 1) about as high as your reservoir, 2) durable, and 3) full of small holes (so the water can get in easily but the wicking material doesn't get out).

7) Cut out a hole for your wick.

8) Cut a geotextile piece that is about 5-10 cm wider and longer than your container. Cut a slit in it and insert your wick. Make sure you cut the slit vis-à-vis the hole for the wick in the container. Put the wick in the hole in the container and lay the geotextile so it extends a bit on each side.

9) Put enough soil in your container to fill your wick. Mix in some perlite (about a fifth of the soil you added).  Dump the mix into the wick. Perlite helps keep the soil light and well aerated, which various macro-organisms normally do in the ground. If perlite and soil are not mixed together before being added to the wick, it can be quite hard to make sure the wick contains a good mixture of both when the container is full. 

If you prefer to mix your soil and perlite before adding them to the container, skip this step.

10) Fill the container with soil and top with perlite. Make sure to keep the geotextile on the sides as you fill the container with soil. Mix thoroughly the soil and perlite. What we're looking for here is the unfamous reversed-color chocolate chip cookie dough mix, where the perlite would be the white chocolate chip and the soil would be the chocolate cookie dough.

If you have "weird" chocolate chip cookie tastes (not sure there's a standard or anything about what is a correct cookie dough-to-chocolate chip ratio), go for 4 parts of soil per part of perlite, or 20% perlite.

Put in the oven at 350F for 20 minutes and enjoy!

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