Today I’ll show you how to build a DIY Raised Planter Box. We’ve been wanting to have some type of elevated planter for a while so we can grow herbs in a small controlled area. I also make a Patio Cooler Grill Cart Combo a couple years ago and it’s a great match on our back deck.
I’m partnering with RIDGID Power Tools for this build and they are giving all my readers a special gift for Father’s Day. Between now and Father’s Day (6/17/18) you can use code RIDGIDDAD to get the DIY Raised Planter Box Plans for FREE! Huge thanks to RIDGID and I hope you can build one and enjoy it with your family as well.
Affiliate links are used on this page. See my disclosure page for info on affiliate programs.
How to Build a DIY Raised Planter Box
- Build the Leg Assemblies
- Assemble the Main Planter Box
- Make the Lower Shelf
- Make the Top Frame
- Install the Bottom and Drainage
- Install the Liner and Plastic Sheet
1. Build the Legs for the DIY Planter Box
I started off by making the planter box leg assemblies. Each leg is made from two 1x4s joined at a right angle. I cut all eight leg parts to the same length, but since I’m using a butt joint to join the legs together, one side of the leg assembly would be ¾” wider than the other without any modification. So I cut ¾” off the width of four of the leg parts and now each side of the assembled leg will be 3-½” wide.
I’ll be joining the legs together with a combination of pocket hole joinery and glue. On an unpainted piece I always hide the pocket hole joints, so I only made holes where they would be covered by the legs or the lower shelf. I only drilled the four narrow parts as they will butt up to the face of the wider legs.
Next I put glue on the edge of the narrow piece and clamped it to a full size leg part and secured it with exterior pocket screws. To get a good bond in the large gap between pocket screws I used a small f-clamp to clamps the parts together while the glue dried. I repeated this process for all four legs and set them aside to dry.
Then I moved on to cutting the front, back and side boards for the DIY planter box. I laid out my cuts so I would get two fronts and four sides from the same 12’ board so the color would wrap consistently around the box. I cut the long boards first from each 12 footer then moved my stop block in and cut the shorter side boards. I think keeping track of the cuts and board layout really makes a difference in the final product.
To add a little detail to the planter box I put a small chamfer on the edge of each of the boards that make up the box with my router. And since I’m not gluing the boards together into a panel this will also help to hide any gaps between the boards as the boards expand and contract with humidity.
Before heading back inside for assembly I sanded everything to 150 grit with my cordless sander so it will be ready for finish after it’s assembled.
2. Assemble the Main DIY Planter Box
I laid two of the leg assemblies out and used side pieces at the top and bottom as spacers to make sure everything was parallel. Then I put down a nice bead of glue where the boards would go and attached the the side panels one by one with exterior screws. I repeated this process on the other side and had my two planter box side panels done.
To join the sides together and form the main planter box, I clamped down a scrap of plywood to my bench as a straight edge reference. Then I butted the sides against it and laid down some glue and put the top and bottom boards in place. It was a bit tricky to keep everything aligned so I used a long clamp on the top and bottom of the panel to position the panels while I attached them with 1-1/14” exterior screws like the side.
To finish off the other side I flipped the assembly over and repeated the process, making sure my boards were laid out with the right color combination.
3. Make the Raised Planter Box Lower Shelf
I went back to the miter saw stand and cut boards to size for the lower stretchers and for the front and back battens. Each of these pieces is 1-½” wide so I cut them to size on the table saw.
I laid out the position for the lower shelf stretchers and glued and screwed them to the legs on each side.
While the planter box was still on its side I attached the front and back battens. I centered each batten then secured it to the top and bottom boards with screws then put a screw in each board to hold them all flush in the same plane.
Next up I cut eight slats all the same size for the DIY planter box lower shelf. To keep the slat edges from chipping and to add a little detail I put a small chamfer on the top edges of each board with my router. When routing all the edges of a board do the end grain first then the long sides. The ends are more prone to tear out and a second pass on the sides will help clean up any tear out that may happen.
I’ll be screwing down the slats to the stretchers so I predrilled holes on the end of each board. To get the consistent spacing and a nice clean look (which you guys know I love) I used a little plastic cabinet hardware mounting jig and drilled an extra hole in it. It worked great and gave me exactly repeatable holes..yay, OCD!
To align the slats on the bottom I started off using some scrap spacers, but ended up just lining them up by eye since my spaces ended up a little under ¾”.
4. Make the DIY Planter Box Top Frame
Next up I cut the parts for the top frame. It’s a simple mitered frame from full sized 1x4s. I started by cutting 45’s one of the short parts to size. I used that part to mark the cut for the second short piece to cut it the same length.
For the long frame parts I got a little smarter and made a 45 on two boards then stacked them together and cut the other sides at the same time. This made getting the same length a lot easier.
To give the mitered joints a little reinforcement, I drilled pocket holes on the underside of each end of the short pieces.
For assembly I laid out the parts upside down on my bench and applied a liberal amount of glue to the short boards. I used a web clamp to pull everything together and referenced each of the corners with a machinist’s square before screwing them together with pocket screws.
Okay, be honest. Who realized my DIY planter box in the thumbnail had a 4 board front panels vs the 5 board panel you see here? Well this was the exact moment I decided the look of the planter box was off. The fifth board made it look way too chunky and the drainage system I figured out didn’t need the extra space anymore.
So I swallowed my pride and took a lesson in failure and setbacks. Luckily I’d not glued the pieces together as a panel, so I was able to use a flush cut saw and remove the panels pretty quickly. Unfortunately the ends were still glued and it took quite a bit of time and persuasion to remove the bits with a chisel. But in the end I’m glad I did it.
5. Install Bottom and Make the Drainage System
The last piece of the elevated planter box was the bottom and the hidden drainage system. The bottom is split into two sides and I cut four cleats to hold the bottom slats.
I laid out marks for the cleats so they had a ½” slope from the outside to the middle of the planter box. Then I predrilled each cleat and secured them to the sides with screws.
For the bottom boards I used the worst of the boards I’d picked up from the lumber yard. I cut them to size then predrilled a hole on each end and laid them in the planter on the cleats.
One thing I’d not seen in other DIY raised planter box plans was the use of drainage away from the planter so it could be on a deck. So I wanted to try something different. The heart of the hidden drainage system is this 2”x3” section of PVC downspout. I positioned the inner bottom boards so the downspout just fit between them, then secured the boards to the cleats.
Then I just evenly spaced out the rest of the bottom boards and secured them to the cleats as well. I marked off some lines on the PVC that would let the spout stick out past the planter. Then I cut that section out using some tin snips. A jigsaw, bandsaw or dremel tool would also do this easily.
With the notch cut out I could mark the top of the pipe for a sloped cut to allow the water to runoff. I cut it at an angle and had the base of my drainage ready. But before I attached it in place I wanted to apply my finish and attach the top frame.
Since I forgot to cut pocket holes in the top of the panels earlier I had to use my jobmax with the right angle attachment to get the job done. It worked, but doing it beforehand would have been a lot easier.
For the finish on the raised planter box I brushed on two heavy coats of spar urethane. I really love how the spar brings out the warm tones of the cedar. And it protects well outdoors.
When the finish was dry I went back and installed the hidden drainage. I just predrilled some holes in the downspout and attached it to the sides of the bottom boards. I’ll show you how it works after I install the liners.
Before putting in the liners I installed the top with pocket screws in the holes I drilled earlier.
6. Install the Liner and Plastic Sheet
The second part of the DIY raised planter box drainage system is a combination of landscape fabric and plastic sheeting. I started by covering the bottom with a layer of the landscape fabric. You really only need a small piece but I covered the whole bottom anyway stapling it in place and made a little trough right over the downspout.
The fabric is just to keep the soil from going out into the drain and clogging it up. The main part of the planter box liner is the black plastic sheeting. I used a 3.5mil sheeting since it seemed like the most heavy duty and cost effective option that could cover the planter seamlessly.
I unrolled and worked the plastic liner into the planter box, stapling it at the very top under the frame. The plastic liner will keep the moisture off the cedar and let your planter last a long time. It also will collect and direct all the extra water down to the middle of the planter.
To let the water escape out of the elevated planter box I poked four large holes in the plastic right above the downspout using a dowel I sharpened on a sander. You can make the holes with anything, just give the water somewhere to escape.
Of course I had to test out my contraption to see if it really worked, so I poured some water into the planter, and viola! The planter drained right out the back just like I’d planned and will keep that bottom shelf clean and dry.
We took the planter box out to the yard to get some good pictures of it and my boys helped fill it up with soil and plants. This could be a great Father’s Day project to do with your kids and use the planter box to garden with your family. We plan on growing some herbs and veggies and letting the kids care for them and learn about gardening and growing your own food. It’ll be a fun experience to do something together as family.
Remember you can get the DIY Raised Planter Box plans for free until 6/17/2018 by using code RIDGIDDAD at checkout.
If you liked this DIY Raised Planter Box you can check out some of the other outdoor projects I’ve built at my Outdoor Projects page.
RIDGID provided me with product and/or monetary compensation as a sponsor of this build. All opinions are my own and are not filtered by the sponsor.