How to Build a Planter Box

Completed wood planter box in a workshop
What You'll Need
Wooden boards, planks, or studs We’re using (3) 8’ 2x4s
2 ½” Course screws
Crosscut saw
Power drill
Tape Measure
Optional: Kreg Rip-Cut

Building your own planter box is a simple project for any DIYer interested in container gardening. A wooden box for flowers, vegetables, or herbs is a great way to grow beautiful plants that will light up any outdoor space, whether or not you have a yard.

This project can be created with any type of wood, and is a great way to use up scrap wood from previous projects! We’re using leftover 2x4s, a common piece of wood many DIYers may have around, but you can use plywood, particle board, fence boards, etc. However, if you’d like to leave your planter’s wood untreated, consider buying redwood for this project as it will last over years as you water your plants.

To achieve a clean finish that will compliment your outdoor décor, as well as creating a strong joint that will work on any thickness of wood you choose, we will be using a pocket hole joint for this project. This will prevent gaps in your planter box so water will fully saturate the soil without leaking at the corners.

To quickly make pocket hole joints, we’ll be using the leading tool for this, a Kreg Jig. We recommend either the Kreg Jig R3, which is small and adaptable, or the Kreg Jig K4, which can make a large amount of dual holes without the need for an additional clamp. Both Kreg Jigs adjust to your specific wood’s thickness to create professional pocket hole joints.

Step 1 – Measure and Cut the Planter Box’s Wood

Cut wood pieces for a planter box

A planter box can be made to any size specifications. Consider what plants you will be adding to your box and researching their spacing and depth needs. Our sample garden box will be a 32x10” medium length container with a smaller depth, perfect for an herb garden. When designing your container garden, include space for a gap at the bottom of the box. This will ensure proper drainage for your plants and prevent root rot.

To follow along with our measurements, use 2x4 studs with the following measurements:

  • (4) 32” side of box

  • (4) 7 ¼” side of box

  • (2) 29” bottom of box

When cutting wood into planks of the same length, it’s important their measurements are accurate. We used a Kreg Rip-Cut to keep our repeated cuts identical to each other. Simply attach your circular saw to their universal shoe, set the determined length on the Rip-Cut’s track, and cut the same length every time without measuring.

Step 2 – Drill Pocket Holes

Wood pieces with drilled pocket holes

Once all your wood is cut for your container garden, use a Kreg Jig to create pocket holes for tight joints. You can either place them on the inside of your planter box for a smooth finish or on the outside, like we did, for an artistic flair.

On your Kreg Jig, set the drill guide to the thickness of your wood. As we’re using standard 2x4s, we set our guide to 1.5”, this will ensure the pocket holes exit in the center of the wood. Place the inlcuded step bit onto the setup gauge located either at the base of the Kreg Jig K4 or in the case of the Kreg Jig R3. Slide the stop collar onto the step bit and secure at the marked thickness of your wood. This will prevent over-drilling, and create the perfect depth every time.

Secure your wood piece to the drill guide, using your own clamp for the Kreg Jig R3, or the attached clamp on the K4. Drill two holes at each joint for a strong joint. If using the K4 jig, use the A and C hole placement for 4” wide material.

Step 3 – Assemble the Garden Planter’s Frame

Wood frames with pocket holes for planter box

Using two of the 32” wood pieces and two of the 7 ¼” pieces, create a frame. Use a Kreg right angle clamp or have a someone with steady hands hold two wood pieces together (one long, one short). Fasten your screws into the joint to secure. We recommend Kreg pocket screws as they feature a self-tapping auger point that not only eliminates the need for pilot holes, but firmly drills into all wood types.

Repeat this step with the remaining four pieces of wood. You should have two identical frames.

Step 4 – Complete Your Planter Box

Wooden base of planter box in workshop

Securing screw into pocket hole for a planter box

Select one frame to go on the bottom and secure a 29” wood piece at the bottom of each side. Make sure there is a proper gap left between the two bottom pieces for water drainage. We went with a 3/8” gap.

Once the bottom is fitted and tightly secured, attach the second frame to the top and you’re done! If any screws are exposed on the box’s interior, you may want to add wooden dowels to keep dirt out.

Step 5 – Optional: Bevel and Decorate

Router smoothing wooden edges of planter box

Rounded edge of wood planter box

For our planter box, we wanted smooth exterior edges so we used a router to bevel our planter box. You may also choose to seal your wood or add decorative elements. The pocket hole joints created using a Kreg Jig will leave a smooth surface for creative design and will ensure a strong framework to keep your plants safe for many years.

A garden planter is a great project to add beauty to your home. Whether you choose to plant small flowers, tasty container fruits and veggies, or a simple herb garden, make sure you properly prepare your planter box. To prevent loose dirt from falling through the gap, line the bottom of your planter with rocks before adding your dirt. This will create a healthy system that keeps your plants hydrated while preventing root rot.