Save water and grow healthier veggies and flowers with a self-watering planter. This attractive cedar design uses perforated drain pipe to store and distribute the water.
The drain pipes are filled with water, which is gradually wicked out by the soil and absorbed by the plant roots.
I love to grow fresh salad greens, tomatoes and herbs. But growing veggies during high summer means daily watering, which becomes a problem when we go away for vacation. In the past, we’ve hired the neighbor kid—sometimes he remembered, and sometimes we came home to withered veggies. Last summer I decided to build “self-watering” veggie planters that I could leave for a week without watering. The results were amazing. The planter boxes themselves were gorgeous, they kept rabbits and other critters from munching on my greens, and I went for weeks on end without having to water. I watered three times all summer long (no kidding), and we had garden-fresh salads until frost. In this article, I’ll show you how to build one for yourself. The secret is in the perforated drain pipe.
Self-watering planters are sometimes called “sub-irrigated planters” or SIPs, because your plants get to “sip” water whenever they want. Our version uses inexpensive perforated drain pipe with a fabric sleeve in the bottom of the planter. Once you fill the drain pipe reservoirs, they allow air to circulate and water to wick up to your plants’ roots whenever they need it. When plants are watered from below, the roots stay consistently moist, there’s less evaporation and you don’t need to water as much. The vinyl tubing allows any overflow water to drain. There are many commercial self-watering planters available—the EarthBox (earthbox.com) is one but you can easily make your own.
Pick the straightest 2x2s for the corner cleats. Align the parts with the corner of your worktable to keep the assembly square.
Straighten bowed boards with a clamp. The top boards need to be straight so the cap will go on straight and tight.
Clamp the edges together and press firmly with the other hand when screwing each plank so everything comes together tightly.
Determine the floor depth (see “Building Tips”), and cut a block that length to mark the locations of the horizontal cleats and joists.
Screw the horizontal end cleats in place first and then the center joists. Notch your deck boards to fit around the vertical supports.
Fold the pond liner at the corners and staple it around the perimeter. Trim the excess.
Cut the perforated drain pipe into 6-ft. lengths. Space the drain pipes evenly along the deck floor, wedging the ends tightly against the short sides of the planter to keep soil out. Pack potting mix around the pipes to keep them straight. Stick a fill tube in the top end of one of the outside drain pipes. The water will flow from there into the other drain pipes through the perforations in the tubes.
In the end of the planter opposite your fill tube, drill a drainage hole just above the height of the pipe. Run vinyl tubing from the drain pipe to the drainage hole.
Extend the vinyl drainage tubing out the side.
Photos 1 – 6 show you how to build a handsome wood planter box. The total cost of my 3 x 6-ft. cedar planter was $330. If you use treated wood, the price would drop to about $250. And I used a thick EPDM pond liner, which cost $120. (You can buy thinner versions at home centers for about $35. All the other materials are available at home centers or garden/landscape centers.) To give the box a nice finished look, we routed the boards and sanded the faces and cap. We left the cedar unfinished, but you could seal yours. After we built the basic box, we moved the planter to its final position and then added the self-watering system, soil and plants. Even without the soil and plants, this planter is heavy!
Photos 7 and 8 show you how to construct the self-watering system. Once you’re ready to plant, add a soilless mix to just below the top of the planter.
Once your plants are in, fill the drain pipe reservoirs through the fill tube until water runs out the drainage hole (this can take a while). The water will slowly wick out of the perforated pipes into the potting mix packed around it and eventually up into the potting mix and plant roots above.
You’ll have to experiment to see how long your planter will stay moist. Fill the drain pipes whenever the soil feels dry 2 or 3 in. down. When I set mine up, I filled the drain pipes and gave the plants an initial surface watering and then mulched around them. After that, and despite a record hot summer, I refilled the pipes only three times over the summer and I had herbs and greens growing until the first frost!
Overall dimensions: 3’ x 6’ x 23 1/2"
For Material List, Cutting List, and Plant choices for containers, see Additional Information below.
Note: We notched the flooring to fit (Photo 5). You can also fit the floor within the 2x2s as shown and let the liner span the gap.
If you like fresh vegetables and herbs from the garden, but don't think you can have a garden, Elisa Bernick, an editor at The Family Handyman, shows you how to build a sub irrigated planter system (also called a self-watering planter) that will allow you to grow your favorite foods and keep them watered, even while you are on vacation.
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.