Friday, May 16, 2008


You would have thought that running out of ground after planting 19 tomatoes would have been a sign that I should stop planting. Alas, the Internet made an appeal to my garden-nerd sensibilities and offered me a spot for one more tomato.

That spot is an on-the-cheap homemade version of a popular self-watering container that retails for 40 to 50 bucks. It's a planter that extends partially into a water reservoir so that water is constantly being wicked up to where the plant's roots can reach it.

There are plenty of fine tutorials online for this project, so I'll lay out the rudiments here and let you delve deeper elsewhere. Josh Mandel is the apparent originator of this thing -- and holy crap, I just found out, also the designer of Space Quest, a classic of computer adventure games. Also, if you wade into the Gardenweb tomatoes forum you'll find two guys who post under the names "rnewste" and "bingster" who are like a couple of tomato-planter mad scientists and have contributed some great innovations.

(update (6/16/2008) "rnewste" is Ray Newstead and he's teamed up with the TomatoFest folks to make his plans widely available as a public service. They've got a great guide online that will tell you everything you need to know and then some.)


Start with a pair of big plastic containers. The main problem with the commercial version is that it's not really large enough for a big robust indeterminate tomato growing anywhere south of Canada. I bought Rubbermaid 18-gallon bins for $6 each.

You also need a rigid basket-like container of some sort. I used a plant basket, which is meant for planting aquatic plants in a pond, although I've seen people use coffee cans punched full of holes. It has to retain soil, but let water in. And you need a piece of pipe, at least an inch-and-a-half wide and taller than your bin.

That's it for required materials. Everything else is optional.

Start by hacking off the bottom of one of the containers at a height equal to the height of your basket. Flip the bottom piece over and cut out a hole slightly smaller than the mouth of your basket, then attach the mouth of the basket to the hole so that the basket is inside the bin piece. I drilled holes and used zip ties.

Drill a bunch of little holes all over the top of the bin piece and one big hole at one end wide enough to fit your pipe.

In that photo, you can see that I lined my basket with a paint strainer for added soil retention, but it's probably not necessary.

Drop that whole assembly into the bottom of your other bin and you're mostly done. I cut some row cover cloth to seal the crack between the pieces to keep soil from dropping down into the bottom compartment, some people have used styrofoam peanuts for that, but again, it probably isn't necessary. Drill a couple of holes in the side of the outside bin slightly below the height of the other piece -- this is to drain excess water.

Now, put your pipe into the hole and fill the container with soil mix, starting with the basket, and wetting it down as you go. Your soil mix is kind of important. Since all of your watering will be done from the bottom, the mix has to have enough wicking capacity to pull the water up to near the top of the planter. The gold standard for this is apparently Miracle Gro Moisture Control Potting Mix. But if you're going organic, you'll need to be sure to have plenty of absorbent content like peat, vermiculite, or perlite. Sadly, I didn't really write down what I used, but I think it was something like this:

2 parts peat
2 parts commercial compost
1 part peat humus,
1/2 part each vermiculite and perlite
a few handfuls of my cottonseed/kelp/bone meal mix

Fill it up to overflowing, then dig a shallow trench near one side and fill it with a strip of your preferred fertilizer. The idea is that the wet soil will gradually dissolve the fertilizer and keep the plant fed over time. I'm not sure if I buy it, particularly using organic fertilizer, but that's what They say to do.

Cover the whole thing with a layer of plastic (I finally found a use for that red plastic tomato mulch I've had laying around) then put on one of the bin lids, after cutting out holes for your fill pipe and your plant in the lid and the plastic. The covering serves to retain moisture, but also to keep rain from getting in -- you mainly want the plant's water coming from below so that the fertilizer doesn't get washed out.

And there it is. Just keep the reservoir full (I've got a stick stuck to a wine cork to test my water level) and play the waiting game.

So is it worth it? Dunno. The tomato I planted in mine, Mortgage Lifter is doing quite well, so I think my soil mix is getting the water to the plant. It is nice to not have to worry about whether it needs watering or not, and I've only had to fill it once so far, although we haven't had real heat yet. I am also desperately needing to set up some supports for the plant, which has blown over in storms twice now.

I'll let you know how it goes.

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