(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.
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.
Here’s how I turned these six basically FREE pots into three sub-irrigated planters, in about 15 minutes or less.
Step 1: Cut, then tear strips of a raggy old towel to make wicks.
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.
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.
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.
Step 5: Set the inner planters, with towel wicks, into the outer planters, resting on the supports.
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:
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.
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!!!