How to Build a Cedar Planter Box

Summertime means plantin' time. It's cool to have stuff on your front porch or on your deck in a lovely planter like this. And, that's what we're gonna do. We're gonna go through the building of this really simple planter. It looks complicated.

That's one of the things I like about this project, because it's got compound angles goin' here, but it's really, really very simple to make. Let's talk about some things that are goin' on here. I use cedar because it's a great outdoor wood and more specifically, I use cedar 1X12s. So in the world of dimensions we're 24 inches across here, 24 inches long. One of the things to do if you're playin' with a design, which you're welcome to do so, is keep in mind that when you create the width across the bottom of the end, don't go too wide, don't go too long down here because eventually we want the cedar 1X12 to make the bottom.

So basically, my design aspect of this was pretty simple. I want the distance across the bottom of the end to be less than the width of a 1X12, so that a single 1X12 will make up the bottom. Everything is cut at 10 degrees. And like I said, it looks like we've got crazy, complicated compound angles here, but we don't, it's simple to do. We're gonna use rabbets on the ends of the front and the back, the ends of the long pieces in order to substantially fix or strengthen our joinery here.

And we're gonna use an exterior grade glue to put everything together. First step, miter saw, and at the miter saw we can get our pieces cut to length. Doin' a lotta cutting here at the miter saw. And what we wanna do is get this set up so that when you're cutting the front and the back, the side and the side, you're cutting the two of those together so that we know they're exactly identical in length. Now, back at the bench I believe I misspoke a little bit.

It's 28 inches long point to long point on the front and the back. And we're gonna need that information here at the miter saw in just a sec. I'm settin' my miter saw to 10 degrees. Lock it. And here's how this is gonna go.

Gonna get one 10 degree cut on the end of this board and a 10 foot plank will do everything we need, all the box parts, including the bottom. Now remember that 28 inch number. I'm gonna measure long point, 28. I don't wanna cut right on that line, I wanna cut to the side of it. Like this.

This will all make sense in a sec. Same thing. Now the reason we do that is so I can do a flip, and a flip. Now we can do our final length. Make sure you've got the left ends lined up.

Long point to long point on your ends. We wanna end up at 14 and a half. I'm just gonna follow the same procedure. That takes care of everything we can do with the miter saw to get our parts cut to the right angle, the right length, and next a little bit of rabbet joinery over on the table saw. Height of the dado head three eighths of an inch, width of the dado head is three quarter.

Now, my cedar's slightly thicker than that so you'll see we have to do two passes to get the rabbet complete. Distance from face of fence to left edge of dado is equal to the thickness of my material. Miter gauge is set at 10 degrees. That's gonna let me do this, and like I said, it'll take two passes to get everything outta there. There we go.

Rabbet hunting is done. So, back to that distance from the fence business, it's so that when your ends go in like this, the end grain of the front and back is just ever so slightly past this face, then you can sand that flush after the glue is dry. Speakin' of glue, let's do that. Glue bench. We're ready for gluin' it up.

Now, couple things about this whole process. When we put these parts together we're gonna have the sides at a 10 degree angle and if you don't take a little preemptive step here, which I'll talk about, clamping can be kind of a pain. So, preemptive step is, when we did the cutting you end up with all of these triangles and what I did on this one is I used a square on that end, drew a line right up the center, then on the ones that are already in place I had gone to the band saw, cut on that line, so I get a caul and a caul. The caul is at the perfect angle, 10 degrees, because we've already cut these from our project pieces. Then I used hot glue to fasten that here so that when I'm clampin' everything together my clamps can go on this instead of this side.

That keeps the jaws of the clamps parallel to each other. Glue is critical. We're gonna have somethin' here that, because you water plants, you're gonna fill this with dirt and water your plants, hopefully. So, it's not just damp, it's wet all the time. So this is a good application for Titebond III because it's waterproof, not water resistant.

So, it's more than water resistant. So we're in an application here where because it's constant exposure to moisture, Titebond III is our best choice. All right then, glue your rabbets. Cedar's kinda thirsty, so I'm just makin' sure I've got enough glue in there. And then I find on this project, upside down is a good way to put this together.

Notice I also put our 10 degree cauls on the ends and that's so I can draw everything this way and get the rabbets closed. All right, so far so good. I'm gonna go long ways first, just a little bit of pressure. That's closin' the ends to the shoulders of the rabbets. Nice.

Now we wanna have enough pressure on there, gonna flip everything. I'm just gonna make sure my clamps wanna stay put. It seems okay. All right, rinse and repeat. The long clamp to draw this in.

All right, last clamp. We'll let this dry and then I'll give you some tips on cutting your bottom so that it's a good fit inside here. Next step, let's put a bottom in the flower box so your flowers don't just fall through. Here's my approach to this. You can use my dimensions for those outside numbers, gave you those numbers.

And when it comes to the bottom I think you gotta just measure your box and get your bottom to fit. Here's how I did it. Inside here I wanna get the width first. So, coming up from the bottom the thickness of my material, in my case it's seven eighths thick, comin' up from the bottom that amount you wanna measure from inside to inside and get that number for your box. Go to the table saw.

Set your table saw blade to 10 degrees and cut your bottom so that long point to long point is that number that we just calculated. That's gonna give you this. Then, either at the table saw with a miter gauge or at the miter saw, cut one end, so now we've got a 10 degree cut here. A really important part of this is I want this off cut, because then we're gonna bring this back to this box. The hard part now is calculating how long this thing is.

And it's not hard. We're gonna make it really easy here. When I put this piece in where the bottom is gonna live, mark it here, then, do the same thing on the other end. Mark it. Because the width of this piece gives it a distinct location inside the flower box and that's what we just marked.

Now I can measure from that mark to that mark and that gives me the overall length of the bottom so that it'll drop in there. So, drop in there, what we wanna do is glue this in. Same deal, we're gonna be a flower pot filled with damp soil, so Titebond III is a really good choice. Tryin' to go fast before it starts to drip. Oh no.

I almost made it. I'm getting Titebond III'd. But while it's wet it is water soluble, so it'll wash off me. Drop this in. Whoop.

And then, you're probably gonna have to reach under and just kinda manipulate it to get it to go into just the right spot, so it's straight, so it's level in there. I'll come back with a damp rag and I'll clean that glue off. I'm gonna leave that one sit because I want the glue to dry before I do this next step, which is, what we have now, if the bottom's a good fit you just built a bathtub and that's no good for plants. So, in the bottom we just wanna make some drainage holes. Quarter inch bit, a piece of scrap wood on my bench so I don't ventilate my bench.

Giving us that, and that'll allow moisture, excess moisture to drain out of this. That takes care of the flower box except for a little bit of sanding. Because of the way we cut the angles and put this together, you'll find that these top corners aren't automatically lined up when you glue this. But, just a little work with a sander or a hand plane and you can feather 'em together. What I like to do is round all the corners so it's easy on your hand when you're comin' and goin' from the planter.

And that, once the sanding is done, takes care of it. It's a cool project, really fast build and this is one of these, I say this on a handful of projects, if you're makin' one of these you might as well just make six at the same time 'cause when people see 'em they're gonna want 'em. So, get this made, fill it up with dirt and flowers and enjoy some summer plantin'.