DIY Large Concrete Planter | Build Your Own for $150

A DIY large concrete planter lets you build a custom vessel for around $150 in materials, saving up to $1,200 over store-bought versions of the same size.

The process uses two nested molds to create a hollow concrete box with 2-inch thick walls, typically 24 inches wide and 32 inches tall. Everything in this guide is based on real builds from experienced DIYers and manufacturer specs — no theory, just the working method.

What You Need to Build a Large Concrete Planter

The core tool and material list is short and affordable. Most items are available at Lowe’s or Home Depot.

Plan for 6–8 bags of 80 lb Quikrete mix for a 24″×24″×32″ planter. Quikrete 5000 high-strength mix handles the weight and weather better than standard concrete. Three-quarter-inch plywood makes the most durable molds, though 5-gallon plastic buckets work for simpler shapes.

You’ll also need a 2-inch PVC pipe for drainage, a rubber mallet, a trowel, a circular saw, duct tape or FrogTape®, and vegetable oil as a mold release. The total material cost lands between $120 and $150.

Step-by-Step: How to Make a Large Concrete Planter in One Weekend

Follow this exact sequence to avoid the mistakes that ruin a pour. Each step comes from documented builds that succeeded on the first try.

1. Build and Prepare Your Molds

Construct two nested plywood boxes. The outer box should measure 24″W × 24″D × 32″H — this defines the planter’s outside edge. The inner box needs to be 22″W × 22″D × 30″H, leaving a 2-inch gap around the sides and bottom. Cut the plywood with a circular saw and screw the pieces together so the outer box can be disassembled later.

Spray vegetable oil on the inside of the outer mold and on the outside of the inner mold. This prevents the concrete from fusing to the wood.

2. Set Up the Drainage

Drill a 2-inch hole through the bottom of the outer box. Insert a 2-inch PVC pipe so it sits about 2 inches above the mold’s base. Cap the top of the pipe with tape or a plastic cap to keep concrete out of the opening during the pour.

For bucket molds, weight the inner bucket with bricks or sand so it stays 2 inches from the bottom. That gap becomes the planter’s floor.

3. Mix the Concrete to the Right Consistency

Sift the dry mix through a screen to break up clumps, wearing a dust mask. Add water slowly until the mix reaches a “peanut butter” texture — thick and cohesive, not runny like a slushee. Overwatering causes cracks during curing, so stop adding water as soon as the mix holds its shape without slumping.

Mix in manageable batches if you’re working alone. A full 6-to-8-bag pour takes about 30 minutes of continuous mixing.

4. Pour and Form the Walls

Pour a 2-inch layer of concrete into the bottom of the outer mold. Set the inner mold on top of that layer, centering it by using 2-inch wood blocks screwed to the outer box edges as spacers. The gap between the two molds must be uniform all the way around.

Scoop the remaining concrete into the gap between the molds. As you fill, tap the outer box firmly with a rubber mallet — this settles the mix and pushes out air pockets. Secure the inner mold with tape across the top to stop it from floating upward as the concrete rises.

5. Let It Dry and Remove the Molds

The concrete needs 24–48 hours of undisturbed drying time. Check the manufacturer’s instructions on the bag as a guide, since temperature and humidity affect drying speed.

Remove the outer mold first by unscrewing the plywood panels. If they stick, a pry bar pops them loose. The inner mold comes out next — for wood molds, a flat screwdriver and mallet usually do the trick. For plastic buckets, slit the plastic with a utility knife and peel it away from the concrete.

The planter should hold its shape without any visible cracking or crumbling the moment the inner mold comes free.

6. Sand and Seal the Finish

Wait 12–24 hours after removing the molds, then sand rough edges and surface bumps with a sanding block. The concrete should be firm enough to hold detail but soft enough to shape.

Apply a concrete curing compound if the planter will sit outdoors. A matte sealant protects the surface from moisture damage and weathering. For decorative patterns, tape geometric designs with FrogTape®, spray-paint over them, then seal the whole thing.

Full structural cure takes up to 28 days, though the planter can be moved into position after the first week.

If you’d rather buy a finished planter than build one, check our tested picks for premium large concrete planters that ship ready to place — these top-rated models skip the weekend work entirely.

Common Mistakes That Ruin a DIY Concrete Planter

Three errors cause nearly every failed pour, according to experienced builders. Knowing them upfront saves wasted concrete and lost weekends.

Adding too much water. The mix should be thick enough to hold a shape when squeezed. Runny concrete cracks during drying and produces weak walls. Add water in small increments and stop at the peanut-butter stage.

Letting the inner mold float. Concrete is dense, and an unsecured inner mold will rise as you pour, leaving the walls too thin at the top or uneven all around. Tape it down securely before the first scoop enters the gap.

Removing molds too early. Twenty-four hours is the earliest safe point. Pulling molds at 12 hours risks the walls collapsing or the surface tearing. If the concrete still feels cool or damp, wait another 12 hours.

DIY vs. Commercial: What the Price Gap Actually Covers

A DIY planter costs about $150 in materials. A comparable commercial cast-concrete planter runs $300 to $1,000-plus depending on size and finish.

Commercial planters use high-strength concrete formulas and factory-controlled curing that eliminates many shrinkage cracks. They also come with drainage already installed and polished finishes. DIY planters accept a small risk of surface hairline cracks and require more finish work. For patios and covered porches, the DIY version holds up perfectly with a good sealant.

Safety and Placement Considerations

Concrete dust is hazardous to breathe. Wear a fitted mask during sifting and mixing, and use rubber gloves to prevent skin irritation. Mix outdoors or in a well-ventilated area.

A finished 24″×32″ planter weighs roughly 100 to 150 pounds, so make sure the surface you place it on can handle concentrated weight. Concrete patios and wooden decks with proper support work fine; lightweight balcony structures may not. Use a sealer if the planter stays uncovered, since rain and freeze-thaw cycles can degrade unsealed concrete over time.

If this DIY route feels like more labor than you want, our roundup of top-rated large concrete planters covers strong models that ship with drainage and a finished surface, ready to fill with soil the day they arrive.