I’ve seen multiple ways of building earth boxes and a few for sale – most of which cost way too much money. Most earth box plans are far too complicated. Some are simple, but require too many buckets. I’ve modified a design I liked, but made it to use only one bucket.
What is an earth box?
Maybe you’ve never heard of an earth box. An earth box is a self-watering soil based growing container. It holds a reservoir of water in the bottom, and draws out water into the soil through a wick. What makes earth boxes unique is that they can be used for both indoor and outdoor gardening. The plant gets plenty of water and there is almost no risk of over watering. They are great for growing almost any vegetable or house plant.
One observation I’ve made is that earth boxes work great for plant growing, but not well for seed starting. The root area remains very moist, but sometimes the top layer dries. If you are starting from seed, you will either need to get your seedlings established and move them to earth boxes, or you’ll need to lightly water to keep the top layer moist until the seedling sprouts and establishes its roots.
1 – 5 Gallon Bucket and lid.
1 – Small Pot or 3 inch Net Pot
1 – Large bag of soil.
1 – 2-3 foot pvc pipe.
A saw – jigsaw or small handsaw.
Drill bit – 1/4 to 3/8
Unibit / step drill bit
Wick – Fiber or other material
Optional – 1/2 inch grommet
Optional – 1/2 connector
Optional – 1/2 inch tubing
The step drill bit is optional, but it makes life much easier – especially if you plan to build these on a regular basis. Name brand step bits are expensive, but you can buy a two-pack at Harbor Freight for around $10 or a three pack from Amazon at the link below. These may not be as good of quality, but since we’re drilling plastic, cheap ones are more than sufficient.
A unibit / step bit is pictured at the right. It can drill holes in increments from 1/4 inch up to 7/8. Some can go bigger.
These bits are wonderful for building hydroponic gardens and earth boxes. They are especially useful when drilling holes for grommets and you don’t know the exact size. Drill small and work upward until a perfect fit is achieved.
Building the earth box.
I know it’s a bucket, but it’s still called an earth box. Maybe the first one was square.
Begin by marking the center. This will be the wick for the reservoir. In this picture, I’m using a net pot, but you could use a small seedling pot. Some people even drill holes and run strips of cloth into the reservoir. I don’t think this is as efficient, so I’m using fiber-fill and a net pot.
I used a sharpie and outlined the pot. Then I cut the whole about 1/4 inch inside the line. I don’t want the hole big enough for the pot to fall through. 1/4 inch gives enough room for the body of the pot, but still gives a snug fit for the lip of the pot.
Next, I’m going to cut the outer rim off the lid. If I cut the lid to be 10 3/4 inches, it will wedge into the bucket about 4 inches from the bottom. This will leave room for 1-2 gallons of water. I used a jigsaw to cut as I rotated the bucket while the lid was snapped into place.
You will need to drill a starter hole in order to get the jigsaw blade started. This is a great time to drill the PVC pipe hole. Using your step bit, work the hole bigger until it’s a perfect match for the PVC pipe. Try to cut the pipe hole so that it bumps up against the edge of your rim, but not cutting into the rim. This way you will have a perfect fit when you put the top plate (inside of the lid) into the bucket.
Once the lid is ready, cut a notch into one end of the PVC pipe. This will allow water to flow freely when you fill the reservoir. If the pipe is flat against the bottom of the bucket, water won’t pass easily.
Optional Drain Plug
This step is optional. To maintain healthy plants, it’s good to change the water on occasions. Once dirt is in the box, it won’t be possible to drain the water without a bottom plug. So I like to install drain plugs. Installing grommets is where step bits are very helpful. This is a half-inch grommet, but the grommet hole needs to be right at 5/8. The wonderful thing about step drilling is that if you are unsure, you can drill a smaller hole, test it, and go one step up if needed.
The grommet should be a tight fit and a little hard to get in. A flat blade screw driver can be helpful as you work the grommet into place. Don’t use a fine blade screwdriver or sharp object. You don’t want to cut the grommet and start a leak. Once the grommet is in place, insert a 1/2 pipe connector. You could install a spigot, but we are trying to keep the cost down.
The pipe connector is a very tight fit, but you can make this a simple task with a little oil. Dip your little finger in olive oil or vegetable oil, and lightly coat the inside of the grommet. The connector will easily slide into place.
Don’t use petroleum based oils. They can corrode the rubber and you don’t want to contaminate the water.
Seal off the fitting with a plug cap. You could also use a small piece of 1/2 rubber tubing. To make an end cap with rubber tubing, cut a piece about 3 or 4 inches long, fold one end back over the tubing and tighten it down with a plastic tie. This will make a perfect seal. You should end with something like this. To drain, pull off the plug.
Now drill two small holes below the lip of the bucket. Place the plate into the bucket with the pipe and strap it in place with a tie.
The final assembly should look like this:
Very important! Once you see exactly where the pate will rest, drill a small hole just below the plate. This will serve as overflow protection. If the reservoir overfills and the soil becomes saturated, the plant will suffer and eventually die. Roots need oxygen. That’s why loose soil is important. It’s also why plants die when over watered. If you have an overflow hole, the pot can never be over filled and the plant will never be over watered.
Now fill the net pot or seedling pot with fiber.
This will act like a wick. It will absorb from the reservoir and the soil will draw from the fiber. It will also act as a filter and keep dirt out of the reservoir.
Use the pipe to fill the reservoir. A funnel helps if you’re adding nutrient. Otherwise, just use a hose to fill the pipe. Water until you see something coming out of the overflow hole.
For tomatoes, Tomato-tone provides the necessary calcium and other nutrients needed by the plant. Before planting, circle the outer edge with tomato tone so it will be available when the roots reach out for it. You can also go a step further and mix in a gallon of hydroponic solution and pour it into the reservoir. Don’t make the solution too rich and only apply the solution once. After this, replenish with water.
An earth box will keep your plants constantly watered with healthy levels of moisture. Once a week, refill the reservoir with fresh water until you see it trickling out of the overflow hole.
The earth box can be used to grow either indoors or outdoors. It also gives you the ability to move your plants inside when a frost is expected.
If you want to cover your soil to preserve water or keep pests and weeds out, use the rim of your lid and a plastic sheet. The lid can snap the plastic sheet securely. Then you can cut a slit and plant your tomato while leaving the rest covered.
In hydroponic systems, it is also very important to use a bucket that doesn’t allow light to pass. In earth boxes, you can get away with a little light if you change your water regularly so it doesn’t stagnate. These silver buckets from Lowe’s work great. The ideal bucket is black, but gray buckets also work fine.
A white bucket or one that allows a lot of light to pass through will have algae problems. Algae is not your friend. If you want to go all out, here is a link for black 5 gallon buckets.
The lid and bucket are sold separately. If paying $20 for a bucket seems steep, go to Lowe’s and buy their house brand silver bucket and lid. Both will cost you less than $5 total. You can also buy a white bucket and paint it black. Any lid will do since the parts will be inside the bucket.
Net Pot: $3.37 for a pack
Grommet and connector: $1.65
PVC Pipe: $4.00
Bucket: $5.00 at home improvement stores
If you build a second box, the fiber, net pots, and PVC pipes are ready to go. The cost of a second bucket would only be $6.65.
Eddie Snipes 2012
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