Three New Sub-i Tomato Planters: $0, 15 minutes

(in case you’re new here, sub-i = sub-irrigated = what’s usually known as self-watering, which is a misnomer I won’t get into because it’s too tedious to believe)

If you want to read more about sub-irrigation, what it’s good for, why I love it, and how I’ve made inexpensive sub-irrigated planters in the past, just click on the “Sub-I” label beneath this post or at left (or, okay, just click here).  If you live anywhere that watering is not always possible, sub-i planters let you keep on growing by wasting almost no water; it ALL goes to the roots, not in the air, on the leaves, or anywhere else.

So I had these two planters sitting around.  I forget where I got them – free or cheap or at the curb somewhere, no doubt.  There are no holes in the bottom of them, which suits this project just fine.  I also had two large pots sitting around (from a similarly unremembered source), with holes in the bottom, that fit inside pretty unobtrusively.  Okay, kind of funny-looking, but I guess that’s okay with me.

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Then, I also had a round planter, quite a bit smaller, but still spacious with no holes in the bottom.  To fit inside that, I found a round hanging planter with the hanger removed.  Nice and snug.

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Here’s how I turned these six basically FREE pots into three sub-irrigated planters, in about 15 minutes or less.

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Step 1:  Cut, then tear strips of a raggy old towel to make wicks.

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Step 2:  Feed the wicks through the holes in the inner pot bottoms, leaving a lot wadded up inside.  I used two wicks per pot.

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Step 3:  Place cheap dollar-store plant pots around the bottom of the outer planter.  These will be the support for the inner planter.  In the case of the round planter, I wasn’t sure I needed a support, but I used one anyway.

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Step 4:  Add a drain hole (or two) around or just below the level of the supports.  You don’t want to try it without a drain hole, even if you think you won’t overwater.  I made two in each of the square planters, and only one in the round.  You can drill the hole, but for me, the easiest way is with a hot knife from the stove, just burning a hole in the plastic from the inside.

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Step 5:  Set the inner planters, with towel wicks, into the outer planters, resting on the supports.

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Step 6:  Fill with soil, but remember to position your new sub-i planters in a sunny location BEFORE adding water – they get heavy when you do that!

Step 7:  Add plant.  But you knew that, right?

Purple plum tomatoes, hopefully happy in their new homes:

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And then I planted the small one with a pickling cucumber and zucchini.  It’s a bit much for a smallish pot, but if they seem crowded later on, I’ll take one out. 

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With this small one, there’s not really a good way to tell how much water is in the reservoir.  The advantage, however, is ZERO water loss to evaporation.  The square planters have a large exposed area of water (all 4 corners), meaning more evaporation and also a potential “standing water” invitation to mosquito larvae.  Hey, maybe I should buy a few goldfish to drop into my sub-i planter water for the season to eat the mosquito larvae!

Happy sub-irrigated growing!!!


  1. Thanks so much for leaving the link to this post as a comment over at MBT's. I was wondering how to make my own sub-i* containers, because I'm a cheap so-and-so. I probably have the right types of pots in my shed. Holla! (*I also hate the term self-watering. I mean, derp, you still have to water them!)

  2. Thanks - and I look forward to enjoying your blog, too! Do read through all the sub-i posts if you get a chance, because these are NOT the most sophisticated sub-i planters you can make on the cheap.
    I much prefer the look and efficiency of the two "closed" models I made with inexpensive pink styrofoam last year.
    These are more like the commercial model in every way, including the fill tube. They are more efficient because there is less evaporation with a "closed" model, and presumably less mosquito incubation, too.
    Though I am tempted to drop a cheap goldfish into each planter just to keep the mosquito larvae down! ;-)
    (knowing me, though, I'd let them run dry and the poor fishies would die)


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