This planter box will work nicely indoors, as its small size won’t take up much space. You could also enjoy it outdoors if you used waterproof glue, a wood species that stands up to the elements and and an exterior finish.

I love improving designs. The first planter box I made was extremely simple. It was joined together with rabbets and dadoes instead of box joints, it had no top, and there was nothing to collect water. This improved design, however, is more useful.

One item that needs to be purchased is a tray to go on top of the removable bottom so any excess water collects in it and doesn’t spill onto the table or other surface the planter sits on. I found the correct-sized tray at Home Hardware, but any hardware or home product store might have something for you.

Sizing the planter

Your planter might need to be a different size than mine, depend­ing on the size of pots you have. Once you’ve purchased the pots and tray, adjust the planter size as necessary. The top of the planter should be at least 1-1/2″ wider than the diameter of the pots, though 2″ is probably safer. The width of the sides will also need to be adjusted. With the lip of the pot resting on the top, the bottom of the pot will need to be equal to, or slightly above, the tray that sits on the sub-bottom. Doing a full-sized side view sketch will help clear up these dimensions. If needed, the thickness of the sub-bot­tom can be adjusted for a good fit.

Breakout

To make this project you’ll need to either buy or make some 3/8″ thick wood. To make it, grab a piece of ash that’s 48″ × 6″ × 1″, preferably jointed on one face and one edge. Set your bandsaw fence to 7/16″. This will account for the kerf of the bandsaw and planing. Resaw the board. If you don’t have a bandsaw capable of this, use your table saw. You can also plane 4/4 lumber down to final thickness.

Planing is the next step. Plane the two pieces of wood down to 3/8″ thick. Use light passes, as thin wood can blow up when planed too aggressively. After planing, cut the wood to 5″ wide with a bandsaw or table saw. I used my bandsaw.

Using a mitre saw or table saw, cut two 14″ long pieces of wood for the faces. Then cut two 4-7/8″ long pieces for the sides.

Nice joinery

There are many options for corner joints on this project. A keyed mitre or a pegged rabbet work well. If you’re really up for a challenge, this is a great time to try hand-cut dovetails, as these boards aren’t overly wide. I used box joints, which are attractive for this planter box.

To cut the joints, I used a simple jig on my router table. The jig runs in the mitre slot of the router table and cuts 1/2″ wide notches every 1″ on the board, leaving exactly 1/2″ between the notches. The 1/2″ sections of material between the notches are the fingers. After adjusting the bit to a hair over 3/8″ high, I started cutting. Make sure to cut into the end grain. Other options are using a table saw with a dado blade.

To assemble your box, clamp the lon­ger board with a vice. After applying glue to the faces of the fingers, tap the shorter board into the joint. Do this for every side. Ensure the project is left square to dry. It’s also possible to only glue part of the joints at a time in order to simplify the assembly process. When the glue dries, use a block plane to smooth out the top and bottom of the box. This ensures there will be no gaps between the top and bot­tom, and the sides.

Make the top

To make the top, cut a piece of the 3/8″ board down to 14-1/8″ long. This ensures that you can flush trim it at the end to get the perfect fit. Next, draw circles that are 3-3/4″ in diame­ter. Remember to check your own pots as they may be slightly different. If your pots are the same as mine you can mark out 11/16″ spaces in between all of the circles, so they’re perfectly centred and evenly spaced. When you’ve finished drawing out the circles, cut them out on a scroll saw or with a jig­saw. After the three circles are cut, glue the top onto the box.

Time for the bottom assembly

The bottom assembly of this box is made up of two parts: the bottom and the sub-bottom. The sub-bottom keeps the box aligned over the bottom while in use. The bottom assembly is removable for many reasons. With a removable bottom assembly the plastic tray can be emptied and filled to keep the plants watered. It’s also removable because it makes cleaning easier. To make the sub-bot­tom, I cut a piece of wood slightly larger than the actual exterior dimensions of the box. Then I cut a piece that was exactly the size of the inside of the box, which was 4-1/8″ × 13-1/4″. Glue them together to complete the bottom assembly.

After the glue dried, I traced the location of the box on the bottom assembly and used my bandsaw to rough the shape of the bottom panel to size. I made sure to stay 1/16″ on the outside of the line. After roughing the bottom to shape, I put it on the box, clamped it in place and then flush trimmed it with a router. I trimmed the top, too, while I was at it. You could also use a block plane to flush the bottom and top to the main section of the box.

Sand and finish

The final step was sanding. I started at 80 grit to round over the corners and remove saw marks, and then sanded up to 220 grit. I made sure there were no glue spots or imperfections. I applied four coats of polyurethane finish to make the planter box durable and virtually waterproof. You should also apply at least a couple coats of finish on the inside.

Using this planter box means you can keep your plants inside their ugly containers without having to look at them. You also won’t have to worry about them spilling water everywhere. But that’s not all; because the pots sit in the water tray, your plants won’t dry out like usual.