Grow It Eat It: Maryland's Food Gardening Network

Self-Watering Containers: Converting a 5-gallon bucket into a mini-garden

“Self-watering” containers represent a relatively new gardening concept. Instead of drainage holes in the bottom, these containers have an overflow hole on one side. The growing medium sits on a perforated platform directly above a water reservoir. Plant roots grow through the medium and into the water. In most cases, water is wicked up from the reservoir into the medium. These containers can be seen as a hybrid between hydroponic gardening (plant roots growing in nutrient-enriched water) and conventional container gardening. Self-watering containers help conserve water and nutrients and make it possible to ignore your containers for a few days.

The simplest application is to place a saucer under a pot. The excess water is wicked up into the media or pulled up by roots that reach the saucer. A number of commercial models are available or you can make your own.

Converting a 5-Gallon Bucket into a Mini-Garden

The ubiquitous five-gallon plastic bucket is considered by some to be the most useful tool on earth, particularly in poor countries. Thousands are buried in landfills or burned each day in the U.S. Thrifty gardeners rescue them from local businesses and use them to harvest, store, and protect crops, carry water and tools, spread compost, and make compost tea. University of Maryland researchers have designed a new use: a mini-garden for vegetables and herbs that recycles water and nutrients and uses only compost as the growing medium.

Materials List:

5- gallon plastic bucket and lid (food grade). Bakeries, delis, and restaurants will often give them away.
7.5-inch section of 4-inch diameter perforated drain tile
6-inch section of ½ inch (inside diameter) plastic tubing
1 ½ inch wood or decking screw
electrical tape
empty 1-gallon milk jug

Tool List:

Saber saw, drill, 5/16 inch and 3/4 inch drill bits, utility knife, hacksaw

Construction Steps

Using a saber saw or band saw cut the lid so that it fits inside the bucket. (The lid will separate the medium from the water reservoir).

Drill 15 holes, 5/16” in diameter, in lid. (Plant roots will grow through the medium and pass through these holes into the reservoir.)
With a hacksaw, cut 3 pieces of 4-inch diameter black perforated drain tile 2 ½ inches long. (These are placed in the bottom of the bucket to support the lid-separator).
Drill one ¾ inch hole with a drill bit 2 inches above the bottom of the 5-gallon bucket.
Cut a 6-inch piece of ½ inch (inside diameter) clear plastic tubing; wrap one end with electrical tape, to create a snug fit, and insert it into the hole. The tubing will sit directly below the separator.
Drive screw through the tubing (inside the bucket), 1 inch from the end.
Cut an “X” with a knife or razor into the shoulder of a 1-gallon milk jug. Insert the end of the tubing into the milk jug and raise the bucket 8 inches by setting it up on a cinder block or bricks.
Decorate and beautify your bucket with decoupage or spray paint (Krylon Fusion™ for Painting Plastic)

5 gallon bucket

How to Use the “Self-Watering” Bucket Garden

Now that you’ve constructed your mini-garden it’s time to get growing! You’ll be impressed by how easy it is to recycle water and nutrients. Fill your bucket with about 4 gallons of moistened medium, plant your seeds or plants, and add 2-3 gallons of water. The reservoir will fill with water and the excess will travel through the tubing into the milk jug. If it doesn’t rain, your bucket will need to be watered regularly— every day in July and August if it’s in full sun each day. It will take 1-2 quarts of water each day to fill the reservoir. Before adding new water, simply pour back the water that collects in the milk jug. Using this technique no water or nutrients are wasted.

Self-watering Container Cutaway View

This is a portable mini-garden but not lightweight. The five-gallon bucket with moistened growing medium and a full-grown pepper or tomato plant weighs about 25 lbs. when the water reservoir is filled.

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For more information, contact Jon Traunfeld, University of Maryland Extension Specialist

Last updated: 01/7/2011