How to build a wooden planter
by Jim Bessey
There are two secrets to building a great wooden planter. Secret one: start with a square plastic patio urn, and build your planter around it. Secret number two is for parents only: let your child help. This is just the right kind of project to share with a kid.
With all the choices available at home and garden stores, why should you even bother to build a planter yourself? The age-old answer is "because you can" - because it's an inexpensive and rewarding project that you can do in an afternoon, one that you'll enjoy for years afterward. Planters are small, so you can make use of leftover materials from larger projects. Or you can raid the "scraps" bin that many home centers use to sell off short lengths of assorted materials.
Start with a plastic liner; that really does matter. If you build your planter entirely of wood, no matter how good, it will eventually rot or crack. Redwood might be the only material you could use without the liner. Most garden stores offer cheap but durable plastic urns for patio plants. You want one that's square and has a turned lip around the top. The size of your liner determines the final dimensions of your project planter.
We're going to build a basic design: this planter will use only square angles, not tricky flares or curves. The beauty of this choice is that it goes with any decorator style and does not require fancy CAD-generated blueprints. Measuring and assembly will be straight-forward; your ten-year-old won't have any trouble "seeing" the idea and intention. That's what makes this project fun!
Measure the top dimension of your plastic liner, just below the rolled lip. Let's say that it's eighteen inches square. To keep things simple, we'll add three inches to each side for our wooden planter. The inside dimension will be 21" by 21", then. As with all great building projects, we start at the bottom: build a pressure-treated wooden base using six 21" lengths of two-by-fours. Assemble those pieces like the top of a pallet: use two(flat) as runners to hold four together. Fasten with weather-proof screws of about two and a half inches long.
The next step is a bit trickier. Place the base with the two runners on the floor, then put your plastic liner on top. Time to measure for height. Read the distance from the floor to the underside of your liner's lip. Let's say that this number is 23" (as an example). We want all the weight of the inner urn to rest on the base, so the top of our planter will be 23" from the floor.
For simplicity we'll build this planter using a readily available material: 1 x 6 cedar boards. (Premium is best, but #2 will work if you buy extra). So far our planter is 21" square (inside) and 23" tall. Trust me on this number, and cut sixteen pieces of cedar 22" long. Each side of our planter will use four pieces, standing side by side and upright. If you can find them, #6 "split-less" (cedar) nails are perfect for this job.
How do the sides go together? Two opposing sides will be flush to our wooden base, and the other two opposing sides will overlap evenly. Since 1 x 6's measure five and a half inches wide, four pieces add up to 22" of width. For the two flush sides we'll need to rip two pieces of cedar down to just four and a half inches wide. A table saw would be your best choice for this, but you can use an ordinary power saw, too.
Time for those nails. Attach the four pieces which add up to 21" first, on opposite sides of your wooden base. Use a notepad or similar item to keep each board about one-quarter inch off the floor (to avoid wicking water up from the ground later). Now assemble the two overlapping sides the same way, and add one nail to each overlap edge: nail from the face of the outer corner into the edge of the shorter sides. Take care not to split your cedar boards. At this point, the top of our planter should be 22 1/4" high. The final step will show why this number works.
Now we need some strength up top. We'll use four more 2 x 4 pressure treated boards. Cut two at 21" and two at 18". These boards will form a ring around the inside, flush to the top of our cedar side pieces. Use clamps or a helper to hold the boards in place while you nail them into position through the cedar. We're almost done!
Here's how we finish this planter. We're going to add a nice decorative cap around the top, using more cedar boards. Cut two pieces of 1 x 6: one at 18" and one at 23 ". Now rip each of these in half, lengthwise. (Table saw?) Nail the two shorter pieces to the top of the planter, cut edge flush to the new inside dimension and even with the inside on each end. The two longer pieces, nailed to match the new outside dimension, provide the finishing touch and form a picture-frame effect.
Now, finally, our planter is exactly 23" tall, and the plastic liner will drop into the center perfectly. If you like, add plastic glides for feet, or you can even drill holes to install casters to create an easily movable planter. Fill your project with dirt or potting soil, perhaps some peat moss and fertilizer, and add annuals or perennials. Viola!
MATERIALS:
- plastic patio pot, square
- 2 x 4 pressure treated: (8) 21" and (2) 18"
- 1 x 6 cedar: (16) 22" ~ (1) 18" ~ (1) 23 "
- #6 cedar split-less nails (box)
- 2 " rustproof screws (appx. 20)