Making self-watering containers

Vegetables, especially tomatos are hungry for waters all the time. To grow them in containers, you perhaps need to wather them twice daily on a sunny day. On the other hand, a consistent watering (dripping) system may take away nutrients in soil. One solution to this problem is to add a water reservior at the bottom of the container.

There are many kinds of light weight plastic plant containers with double walls on the market. Do not follow manufacturer's instruction to drill holes at the bottom all the way through. You can easily make self-watering containers from them.

The following picture shows a self-watering container that I made for growing tumbler tomato:

Step 1. Drill six 3/8" or 1/2" holes evenly in the inner wall. Do not drill through the outer wall.

Step 2. Drill some 1/2" holes at the bottom in the outer wall. Do not drill through into the inner wall (this is very important!) Some containers already have pre-drilled holes with plugs. If so, just pull plugs off.

Step 3. Cut a piece of metal mesh (you can get the mesh from home improvement stores. They are used for the construction of exterier stucco walls). Cut it in square and bend the four corners upward in order to fit into the round container at the level shown in the picture.

Step 4. Optionally, cut a small hole at the center of the mesh and insert a 3/4" or 1" PVC tube all the way to the bottom of the conatianer. The other end of the tube should be highier than the top soil surface. You can monitor and measure the water level from the top of the tube by a stick.

Step 5. Fill soil and plant. Do not use fine grained or sandy soil. I use 50% compost. Cover mulch on top. I use cedar chips.

Hi Frank, the water will be held under the bottom of the planter and will flow through the holes at the side of the inner wall and flow out through the holes in the outer wall at the bottom. The water level is just under the metal mesh that holds the soil. I hope my explanation makes it clearer.

For planters without two walls, I may use one of the following methods:

1. Put a plastic buket or bowl at the bottom and cover the top with a piece of metal mesh.

2. Cut a piece of thick sponge and put it under the bottom of the container, I'm not sure whether this is a proper method. Just for experiment, I made three pots this way a couple of days ago.

3. For rectangular cedar box, I use 1"x4" cedar board to make a frame at the bottom and stapled 6mm platic sheet to form a water reservoir. Put a piece of rock at the center and then cover the water reservoir with metal mesh.

4. Simply seal the bottom hole(s) and drill holes at sides. This is what I did for the plant boxes on the deck rail.

5. If none of the above methods work, add water absorbing crystals into soil.