In my futile quest to attract monarch butterflies to my yard, I recently planted swamp milkweed (Asclepias incarnata). There are other kinds of milkweed (e.g., the orange-flowered A. tuberosa, butterfly weed) that you can plant here (Zone 7A), but adult monarchs really like the flowers of A. incarnata and the larvae really, really like its leaves. The problem is the plant likes to be consistently watered, which is hard if you leave the house for a few days in the summer. So I decided to plant a few plugs into a large pot equipped with a makeshift olla. Ollas are those beautiful, unglazed terracotta containers used around the world to irrigate crops without much water waste: you bury them next to your plant, fill them with water, and then they slowly release moisture into the surrounding soil.
Anyway, photographs of what’s in my garden are probably TMI, but I wanted to share so that others might be guilted into planting some swamp milkweed, too. If more people maintained host plants, more monarchs will come … and who wouldn’t want that??
If you’re on board, make yourself an olla with a terracotta pot glued to a saucer. Or use two pots together — just ensure that you’ve got something watertight. I’m fond of Loctite Premium and Gorilla Glue for getting the components sealed together. Note that you must use unglazed pots. To facilitate filling of the olla, attach something funnel-like. For this olla I used a lamp reflector bowl that I found on sale at a hardware store; because I needed a little more height, I attached the funnel on top of a little bit of PVC tubing.
Next, equip a planter with a plastic liner so that water will pool a bit at the bottom. Alternatively, if your planter is wood or plastic and lacks holes at the bottom, just drill a few drainage holes midway up the sides.
Here’s a photograph showing the olla inside the planter.
Here’s a really boring video of water being added to the olla. But I sped it up so you don’t suffer too long. But you can skip this and I won’t be offended … I’ve just found that when explaining the olla concept to the uninitiated, they don’t get it unless showed.
Once filled, you can see the porous nature of terracotta almost immediately. I think this pot is particularly porous (perhaps firing temperature was too low).
Add some sort of floating ball to your funnel so that when the water level goes down, the ball acts as a stopper for the olla, preventing evaporation. Other people have caps for their ollas — that works, too. I’ve never seen balls used before, and they amuse me. Yes, I’m easily amused. Also gives me a quick visual for when the funnel level has dropped.
After you’ve confirmed that olla doesn’t leak from the glued seams, add soil and plants. Of course, if your olla leaks, dry it out and add glue or caulk (the white stuff you see at the bottom).
This shows how the ball (ping pong ball) seals the neck. Works like a charm.
Now I’m waiting for the darn monarchs. I hate this part.
By the way, ollas work well for any plant. I have about 10 in my garden, all homemade (you can buy fancy ones, but shipping terracotta is expensive). Really great if you find yourself traveling during the summer, or have plants that don’t tolerate even a single day of neglect. If you hook them up to rain barrels via a siphon (future post), you can have pots that water themselves entirely.