How to Make a Two Bucket Sub-Irrigated Planter (SIP) – (Green Roof Growers)

Bruce FIELDS from Chicago sends this message :

I thought you might like to see this.

I think these planters should be self watering. As in hook up a hose and you’re done watering. For the summer. I knew I wanted to work with one of the strengths of the SIP, its water reservoir, rather than adapt watering systems and techniques used for ordinary container or garden irrigation. While it’s possible to run zoned drip lines or soaker hoses, they both have drawbacks. What I came up with is inexpensive, has no moving parts or timers, uses a minimum of water, is easy to set up and operate, and (almost always) works. I think I’ve got a way to make it foolproof, more on that in Part 2. It’s based on what, at first glance, seem like complicated ideas. However, most people intuitively understand what’s going on, it justtakes a few convoluted sentences to explain why it works.

This is a simple, easy-to-do project that will let you grow your own food wherever there’s enough sunlight–on your roof, balcony, back steps, driveway, or vacant lot next door. It doesn’t take any special skill and the materials are all readily available. A diagram showing what’s going on inside a SIP is here. The fundamentals are the same whether you use buckets, tubs, or Earthboxes.

Once you make one, it will produce beautiful food for years to come. You’ll decide that one (or four, or six) isn’t enough and you’ll want to build lots more. This year we expanded with the ten extras at left.

Many of the photos here are from this second SIP run on the roof, and the pretty yellow pickle buckets are courtesy of Bruce’s neighbor who drives for Chicago’s own Vienna Beef (Thanks, Rey! We owe you some tomatoes).

While these instructions are full of details, what you want (a healthy, productive plant) doesn’t depend on following them exactly. It doesn’t need to be perfect. The holes you cut can be raggedy and you’ll still get pounds of tomatoes from one plant. Just try it. And if you get better results by doing it differently, we’d love to hear about it.

Materials and Tools Needed

Two 5-gallon food grade buckets

One 1″ diameter watering tube, about 3″ longer than the height of one of the buckets, made of safe(r) plastic, copper, or bamboo

One 16-oz or 24-oz safe plastic drinking cup
One 13-gallon plastic trash bag
One cubic foot potting mix (not soil)
Organic fertilizer (one cup per bucket)
For tomatoes only, Hydrated lime (one cup per bucket mixed into top 6 inches of soil)

Electric or cordless drill
1/4 inch drill bit
Box cutter/utility knife
Snips or heavy duty scissors

If you’ve got hole saws it’s far easier to cut the two big holes. If you don’t have them, you’ll just have to do a bit more work.

View this quick video for a sense of how the whole thing comes together.

While it’s obviously sped up, it helps to see one done before you try it yourself. Plus, we like the drums.

So now you’re ready to make one.

This is the fun part. You get to drill lots of holes in one of the buckets (set one bucket aside and don’t drill it):


Published by

Willem Van Cotthem

Honorary Professor of Botany, University of Ghent (Belgium). Scientific Consultant for Desertification and Sustainable Development.