Introduction: Upside-Down Hanging Self-Watering Earth-Filled Box!

I've been using DIY versions of a self-watering container with a name similar to "Dirt Box" (or "dearth box") as well as upside-down tomato planters for the past couple years on my concrete, second-story balcony. Here's how I took the basic wicking water principles of a popular patented and trademarked earth-filled box, and applied it to my upside-down hanging tomatoes.

Upside-down planters are cool. The major weak point has always been keeping the plants hydrated, especially during the peak of summer while producing fruit. In the first year, with no special consideration for watering, my plants suffered due to my unwillingness to schlep water to the porch and lift it all the way to the top of each planter. I mean every day?!?! Come on. It was never going to happen.

Last year, I tried drip irrigation. I suspended a tank of water above the level of the top of the upside-down planters and ran a thin hose across the tops of the planters with drip nozzles. The problem was that I could never get the water balanced so the first planter would get the same amount of water as the last. I also had problems getting them to drip slowly enough to last all day. Most of the time, I would be able to keep them hydrated but there was a lot of waste as the the water would run through the plants after an hour or less. Going away for the weekend meant severe drought damage.

I made my own planters in the style of the planters named after a popular planet and marketed by a company with at least one trademark attorney, and that was the best thing to happen to my balcony. I could be relaxed about watering and my vegetable plants thrive. This year, I finally figured out how to give the hanging tomato planters a reservoir without adding weight to the planters and losing dirt volume. After setting up this system, 100% of the water is going into the plants. There is absolutely no run-off waste.

Step 1: Overview

My system has four planters and one reservoir. There is a hose from the reservoir that runs horizontally under the planters. Each planter has a hose at the bottom which is fat enough to contain wick. This hose is connected to the horizontal hose. The wick is about 10 inches long with half of it in the hose and half inside the planter. I made the reservoir out of a 4' long section of 4" diameter PVC pipe. The reservoir should be hung so the lowest point of the reservoir is just barely higher than the lowest point of the wicks. The reservoir should also be shallow enough that the water at its highest level is below the dirt. The water travels freely from the reservoir down the hose and back up into each wick. The wick, using the power of capillary action, takes the water up into the dirt where the plant roots have a party. If you understand this concept, you're 80% done.

My setup is only one example of how this can work. You can use this as a guideline to make 1,000 planters with 20 reservoirs. Go according to the materials you can acquire and what physics will let you get away with. While planning, always be mindful of how much your planters and reservoir will weigh when they are full, how strong the chains are, and the connections that hold them in place. My assumption is that you can figure out how to hang these large, awkward items in a safe way. I will show you how to build the parts for water and dirt.

Step 2: Materials

Since my system evolved over several growing seasons, I used stuff I already had. This instructable shows how I made mine, but since you are starting from scratch, I would recommend some changes (unstructable?):
  • Clear hoses are cool and useful to see if the system is working properly. However, sunlight + water + nutrients = algae. The algae hasn't been troublesome, yet, but I thought you should be warned. If you use clear hoses like I did, you might want to cover them with an opaque material.
  • The horizontal hose is 1/4" ID (inner diameter). The wick hoses are 3/8" ID. If I were you, I would make all the hoses the same size as the wick hoses to simplify the connections. In my instructions, I will call for 3/8" hoses even though the pics show 1/4" hoses.

All of my materials were purchased off the shelf at my local home-improvement store which is not even that good. I recommend reading the entire instructable to understand how this fits together before purchasing any connectors.

  • 10-quart wastebasket/bucket (Umbra Garbino works great)
  • Lid or mulch to cover the dirt on top
  • 2" length of 1" diameter PVC (often available in lengths greater than 2" at a discount)
  • 12" length of 1-1/4" diameter PVC pipe
  • End cap for the 1-1/4" diameter PVC pipe
  • 10" wick that can fit inside a 3/8" ID hose (I used tiki torch wicks)
  • 6" length of 3/8" ID hose
  • (1) quick-connect male connector to connect the hose to the planter. THE WICK MUST BE ABLE TO FIT INSIDE (a barb-style connector will be a lot more difficult to use).
  • (1) quick-connect "Tee" connector to connect to the wick hose to the main horizontal line (unless this is the last planter on the end--then this should be an equivalent quick-connect elbow)
  • Small tomato plant (between 3" and 8" tall)
  • Good soil/compost mix (add some limestone to prevent blossom-end rot)
  • Some foam, gravel, or other material to raise the soil off the bottom of the planter

  • 4' length of 4" diameter PVC pipe
  • (2) 4" diameter PVC female adapters
  • (2) 4" diameter PVC male plugs
  • Quick-connect stop valve that connects to 3/8" ID hose
  • Some trustworthy pipe hangers and chains or cable. The reservoir will be heavy and unmanageable when full.
  • A large cork (possibly from a large bottle of good tequila)

  • Elbow connector, barbed for 3/8" ID on one end and threaded on the other
  • 8-10" length of 3/8" ID hose
  • Tiny piece of cork (smaller than 3/8" but large enough to see)

  • Enough 3/8" ID hose to reach from the reservoir to the furthest planter. Then get a few more feet so you can make mistakes. (hose is pretty cheap)
  • A few square inches of screen mesh to keep out mosquitoes
  • A rotary cutting tool to cut PVC and the wastebaskets/buckets
  • A fat soldering iron if you prefer to melt holes in plastic. I do. (ventilated area, blah blah blah)
  • Hot glue or sealant
  • PVC cement
  • Teflon ribbon for fixing hose connections and leaks
  • A ladder, step stool or long arms

Step 3: Make the Planters

The basics of the planter is a bucket with two holes in the bottom. One hole for the plant. One hole for the wick. When you cut the holes, cut them smaller than you think they should be. If you don't get it perfect, it's much easier to widen the hole. I used a rotary tool to cut the bigger hole and a soldering iron to make the smaller hole.

Do the following for each wastebasket/bucket (hereafter referred to as "the planter"):

  • Look at the bottom of the planter.
  • Cut a hole for the plant 1" in diameter in the center of the bottom of the planter. (fig. 3a)
  • Cut a hole for the wick 3/8" in diameter near the first hole in the bottom of the planter. (fig. 3a)
  • Based on other guides I've seen on the internet, I chose to raise the plant above the level of the hole. I suppose you could skip it. If you don't want to raise the plant from the hole like I did, skip this step. Glue a 2" length of 1" diameter PVC pipe to the inside of the plant hole so the entire length of PVC is on the inside of the bucket. Use lots of glue so it's sturdy and seal it well. (fig. 3b)
  • Screw the threaded end of the 3/8" ID quick-connect male connector into the wick hole from the outside of the planter so the quick-connect end is on the outside. (fig. 3c)
  • Seal this connection with hot glue or some kind of sealant.
  • Get half of the wick into the 6" length of 3/8" ID hose (fig. 3d) and connect it to the outside of the planter, threading the other half of the wick into the planter through the wick hole. (fig. 3e)
Your planter should now have a bare wick sticking up 5" inside and a hose with the other half of the wick, sticking out of the bottom.
  • Attach the quick-connect tee connector to the end of the hose, so the connector looks like an upside-down letter "T." For the last planter, substitute the tee connector with the quick-connect elbow.

Now to make the aeration tubes so the roots can breathe... (you can skip these steps if you like, but I think this helps the plants)
  • Put a bunch of 1/4" diameter holes in the 12" length of 1-1/4" diameter PVC pipe. I used my soldering iron.
  • Put a 1/2" diameter hole in the end cap
  • Cover this hole with a small piece of mesh. Glue it in place on the inside of the end cap. This will help keep away the mosquitoes if the planter has standing water inside. Set this aside until you are ready to insert the plant..

Step 4: Hang the Planters and Insert Plants

Fill and hang each planter one at a time. So for each planter...
  • Attach chains to the sides of your planter for hanging.
  • Hang the planter on a low hook, temporarily, where you can easily reach into the top and touch the bottom. If you are tall and strong, you can just hang the plant where it will live.
  • Cover the bottom of the planter with an inch or so of foam, gravel, or other material to raise the soil off the bottom. Make sure not to cover the wick. The wick should poke through this layer and stick straight up into the soil.
  • Gentlyremove the tomato plant from its plastic nursery pot, turn it upside-down and fold the leaves into the hole as you lower it into the planter. The dirt part of the plant should rest on its own and the green part should stick out nicely from the bottom.
  • Place the aeration tube in the planter, along the planter wall, with the end cap on top.
  • Fill the rest of the planter with your soil/compost mix, making sure the wick stays as vertical as possible, reaching up into the soil. Add some limestone to the mix now to avoid blossom-end rot (you can learn about that on the internets).
  • If you used a temporary location to hang the planter, move the planter to its home.
  • Lightly water the plant. It's advisable to water your plant after you moved it. It will be quite a bit heavier.
  • Cover the dirt with a cut foam piece or some kind of mulch. The aeration tube should stick out the top.

Step 5: Make the Reservoir

Before making the reservoir, calculate the potential weight. Originally, I spent a little too long with a pencil, paper and calculator trying to convert five different units and correctly apply my high school geometry. As of the time of this writing, I found it much easier to run the following query into Wolfram Alpha: What is the volume of a cylinder 4 feet long with a diameter of 4 inches? With the dimensions I entered, it told me that the volume is 2.611 gallons and this much water would weigh 22 lbs. Substitute your own figures so you can calculate the volume of water you can safely suspend.

  • Glue/cement/seal the female adapters to the ends of the pipe.
  • Holding the pipe horizontally, make a hole at the bottom towards of one ends and insert the stop valve. Seal it. Keep the valve near one end so the system can use every last drop of water with the reservoir at a slight incline.
  • Make a larger hole at the top, close to the opposite end, for filling. Large enough to fit a garden hose or whatever you will use to fill it.

Optional water level gauge
  • Make a hole next to the stop valve. Insert and seal the male-to-barb elbow in place with the barb on the outside, facing the front. The "front" is the side you will stand on to view the water level.
  • Fit the hose on the barb.
  • Place the cork ball in the hose.
  • Jam a small piece of screen mesh into the end to keep the skeeters out and the ball in.
  • Glue or tie the hose against the pipe so it stands up.
  • Look at the ball.

Finish the reservoir:
  • Screw the male plugs onto the ends.
  • Drink a fancy bottle of tequila.
  • Put the cork in the fill hole.
  • Hang up the reservoir near the planters.

Step 6: Hook 'Em Up!

So you've hung everything up, despite your wife or your neighbors and you're giddy with anticipation. Time to hook it up.

  • Cut and connect a length of hose from the reservoir stop valve to the quick-connect tee connector on the first planter." Don't make the hose too short. It's good to have a little room to raise, lower or move the reservoir or planters.
  • Connect each planter to the next in series.
  • Put water in the reservoir.
  • Stare at it and wonder if it's working. Water moves through the wicks slightly faster than paint dries. In a couple days, you will be pleasantly surprised to see your plants are still alive and happy and you will be able to relax.

When I first hooked everything up, I noticed some air bubbles gathering under the wicks. I worried that they would block the water from being absorbed by the wicks. Punch a small hole just above the bottom of the wick. Squeeze the area around the hole until water comes out. Patch the hole. Teflon ribbon does the job very well.
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