Water-saving containers? I can hear some of you thinking. Are you kidding? Containers dry up quicker than anything.
Well, it’s true. Some of them do. But if you get, or make, the right kinds, your containers can save you water and also save your plants from that phenomenon some container gardeners know very well: death from neglect.
By choosing bottom-watered containers made out of the right materials, I water my container plants twice a week in the really blistering-hot spells; most of the summer, I water once a week.
Bottom watering. Plants actually love bottom-watering. It gives them a steady supply, without the stresses and strains they go through when water dries up, then they get it again, then it dries up…and so on. A consistent supply of water seems to make them very happy, and that’s not just my observation. Self-watering container promos are full of testimonials: “How I grew 50 pounds of tomatoes in one box!”
You can bottom water by using self-watering containers with built-in tanks, like the one in the photo at the top of this post. (The hole is where the hose goes in.) You can also make a self-watering container by inserting a tank into an ordinary plant pot, or by putting that ordinary plant pot into a bulb bowl.
Containers with built-in tanks. These are expensive, but they last for years (none of mine have worn out yet, and I’ve had some for about a decade) and save you water. I have gotten good ones through Gardener’s Supply and Park’s Seeds; other catalogues also carry them. Earth Boxes are a tall rectangular version of this; others are flatter wider rectangles, squares, and more-or-less traditional round pots. Some of the fancier versions have molded designs and bright-colored resin finishes like glazed ceramic. They come in sizes from smallish hanging planters and pots to honking huge porch planters.
Containers with tank inserts. Here you have two options: buy them (I get mine from Gardener’s Supply) or make them yourself. The basic principle is that there needs to be an insert that keeps the roots out of the tank, but allows the water to wick up into the soil. Here’s a video on making your own self-watering containers from videojug. If you don’t have high-speed, or you’d like to look at another variant of this, try this site for a writing-and-photos version. The homemade versions may not be glamorous, but you can’t beat the price. And you can do what I do with my cheap pots: hide them behind the nicer ones.
A watering tube poking out of a pot with a reservoir insert
Containers in bulb bowls. Of course you don’t have to use bulb bowls; you can use basins or old turkey roasters or plastic buckets or whatever you have handy that strikes your fancy. But bulb bowls are cheap, and they look presentable. I mean plastic bulb bowls, of course; terra cotta ones suck up water way too fast. I leave the plugs in, so they hold water, set the pot in the bowl, and voila, instant reservoir. If you live in country that’s mosquito-prone, you may not want to provide so many lovely brooding areas for the whiny flyers. But in my dry-summer climate, this is a workable, cheap approach to bottom-watering.
Ollas. While filling in the research for this post, I ran across an article about an ancient method of bottom-watering, used in meso-America. Porous ollas (terra cotta water holders) are buried in the ground with only a fill-hole showing. When filled, they gradually seep water into the ground. Apparently, you can use smaller ollas in big containers, though I haven’t tried this yet myself. This site shows a clever, inexpensive modern adaptation of the ancient olla method that even allows you to “automate” watering (no electricity or running water needed).
Using the right materials. I’m a big fan of terra cotta – aesthetically speaking. But for those of us who live in dry climates, and for anyone who wants to conserve water, terra cotta is a bad choice. It acts as a wick, sending moisture from the soil the outside air (the same principle that makes it such a good watering tool when it’s buried, as the ollas are). It’s easy to kill a plant in a terra cotta pot in a single extra-hot day. So I use mostly nonporous pots made out of resin and plastic; I have a couple of glazed ceramic pots, too, but they are pretty pricey and very heavy so mostly I stick to synthetics. They’re making synthetics less awful-looking these days, and the plants cover most of them up. I do have a few terra cotta pots that I use for plants that like a true xeriscape, and I hide some of my less glamorous ones with them.
I do have ecological concerns about plastic, but when I put that against the gas cost of shipping heavy terra cotta, and the fact that the heavy-duty resins last for over a decade (and counting), it seems to me that the artificial materials still come up as the best choice, unless you have local people who turn out large pots. If you make homemade self-watering containers, consider using some type of heavy-duty container as your base. Thinner plastics may start out cheaper, but after a few years they start chipping apart, especially if you leave them in sun. This is the voice of experience speaking.
Next post: Water-conserving potting soils
JUNE: A MONTH TO HONOR WATER
In a way, my whole blog is about low-water gardening; that’s the reason I got involved with tulips, and I already loved natives and Mediterranean herbs. During June, my posts will all be about conserving water in the garden. This gives me scope to cover everything from containers to cityscapes, soil to site to sprays, and of course portraits of more of those stellar plants that spread their glories with little or no watering. (Hint: the “Wild Plants” category will give you quite a few more; so will the “Bulbs” category.)