The Self-Watering Planter Project

A friend of mine commented last week that I should be taking pictures of some of the interesting gardening and homesteading projects I'm working on around here and post some how-to blog entries- so here it goes!

Yesterday, I built my first self-watering planters from materials we had around the house. In the hot Georgia summer sun, containers can get dried out very quickly and I often have to water twice a day. A self-watering planter has a reservoir at the bottom to allow the plants to take up only as much water as they need to keep the soil moist and the roots happy. They are expensive to buy in the garden store but really easy to make at home. Here's what I did:

1. We buy cat litter for our five cats in large buckets and have a number of the buckets hanging around the house. Stacking two of them together gives a space (the reservoir) between the bottom of the top bucket and the bottom of the second. The buckets we're using are around 3 gallons and I wouldn't use smaller ones if you're growing a large plant. Two five-gallon round buckets will also work great for this project.

2. In the bottom of the top bucket, I first made the largest of the holes for the reservoir pipe. We had 1 1/4 inch PVC pipe laying around, so that's what I used, but it could be a little smaller or larger diameter. You will be pouring water through it, so don't make it too small. I used drill bits that are used to drill locks and handle in doors (I'm sure there's a more technical name for them but I have no idea). Ours are called "Blu-Mole". Remember that the PVC size relates to the inside diameter so you will need a drill bit a little bit larger. I found that a 1 3/4 inch bit made the perfect size hole. I then drilled several smaller holes (mine are 11/32 inch only because that was the drill bit I had handy). The smaller holes will hold the wicks and a few should be left over to drain the soil into the reservoir if you get torrential rains.

3. The next step is to drill overflow holes. If the reservoir overfills, it's important that the water can drain out and not flood the roots of the plant. Put the "holey" bucket into an intact one and note where the bottom of the top bucket is. Drill four holes (again, I used the 11/32), one on each side, of the bottom bucket just below the bottom of the top bucket. This ensures that the reservoir can never be fuller than that level.

4. The PVC reservoir pipe has to be a little bit longer than the two buckets stacked together. I had a 4 foot piece laying around and found that cutting it in half made the perfect size for my buckets. You can cut the pipe by hand but using a mitre saw makes it so much easier. Cut two notches into one end of the pipe about an inch long so that water can flow out and into the reservoir.

5. I rummaged around in my rag bag to find material for the wicks. Be sure to use cotton or some other type of absorbent material. I used an old pair of track pants but old t-shirts or dish towels would work just as well. Cut five wicks for each planter. They don't have to be pretty! They have to be long enough to dangle into the reservoir from the bottom of the top bucket. Mine were about 10 inches long and about 3/4 inch wide. Thread each wick through two adjacent holes in the top bucket so that the ends dangle evenly through the bottom of the top pail. Make sure that you have drilled enough holes so that there are two or three left over without wicks to allow drainage into the reservoir.

6. Fit the top bucket into the bottom and insert the watering pipe, notch end down. Fill the top bucket with a light soil mix and plant. Fill the watering pipe with water until you see a trickle coming out of the overflow. That's all there is to it! I made two at the same time yesterday and it took a while because I was figuring it out as I went, but it would probably take less than an hour to put one together now.

 A couple of notes: How often you have to fill the reservoir depends on the type and size of plant, the weather, and a number of other functions. Start by refilling every other day until you can assess how much you have to put in to top it up. I expect I will have to fill the reservoir twice a week for the large tomato plants I put in mine. Also, the soil will often look a little dry on top because the water is wicking up from underneath. Keeping the top of the soil mulched will help keep the top moist as well. These are great planters for the deck. In hot climates like ours, shading the bucket itself from the harsh sun will keep the soil cooler. In northern climates, keeping the planter in full sun will warm the soil nicely. If you are the Martha Stewart type, I suppose you could paint the buckets and make them look pretty, but I'm all about function over form, and it doesn't matter to me that the buckets still say "Tidy Cats". :)