The large size of these planters seems intimidating, but it is actually very simple to make.
Large concrete planters have become increasingly popular as they add an architectural touch to your garden, patio, or indoor space. They provide a durable and long-lasting home for your plants while also offering endless design possibilities. In this article, we will guide you through the process of making your very own large concrete planter that will not only be functional but also serve as a statement piece in your chosen space.
Creating large concrete planters can be a simple and cost-effective DIY project. With the right tools and materials, such as Quikrete Countertop Mix, Quikrete Translucent Concrete Stain, and some basic formwork, you will be on your way to adding a bold and modern touch to your surroundings. This step-by-step guide will provide you with the necessary instructions to ensure you achieve the perfect large concrete planter for your needs.
While this project may seem challenging at first, the satisfaction of completing it and the final result will make your efforts worthwhile. So, whether you have experience working with concrete or are just starting, this article will provide you with the insight and knowledge needed to successfully create stunning, custom large concrete planters.
Materials and Tools
Selecting Concrete Mix
When making large concrete planters, it’s essential to choose the right concrete mix for a durable and long-lasting result. One recommended option is the Quikrete Countertop Mix, as it is easy to work with and specifically designed for casting projects. Using about three 80-lb. bags of this mix will be sufficient for creating large planters.
Choosing a Mold
The mold plays a crucial role in shaping your concrete planter. For large-scale planters, one option is to use Quikrete Quik-tube building forms with diameters of 16″”, 12″”, and 8″”. You can also consider using a 5-gallon bucket or even create custom cardboard molds by cutting and securing them with sheathing tape and screws. Regardless of the molding technique, a utility knife is essential for creating precise cuts.
Gathering Additional Supplies
In addition to the concrete mix and mold, you will also need the following materials and tools to complete your project:
- Sand and water to adjust the consistency of the concrete mixture
- A concrete trowel for smoothing the surface
- 2-gallon bucket for mixing concrete
- Corner braces for added support to the mold
- Canola oil spray or non-stick cooking spray to help release the planter from the mold
- Plastic bag to cover and protect surfaces
- Drill/driver with a ¼-inch bit, essential for loosening drain dowel
- Hammer and chisel for punching out drain dowel
- Wood slats to support the structure as it dries
- Screws to secure slats and corner braces
- Bricks or weights to keep the mold in place
- Respirator P2091 Filters to protect from dust particles
- Sandpaper for smoothing the planter surface after it has dried
Creating the Mold
Cutting the Cardboard
To create the mold for a large concrete planter, start by cutting cardboard to size using a utility knife or circular saw. These tools provide clean and precise cuts, ensuring that your cardboard pieces fit together seamlessly. Cardboard is a cost-effective option for building a temporary mold, as it can be easily cut and shaped to create the desired form.
- Determine the desired height and width of your concrete planter.
- Cut the cardboard into rectangles corresponding to the planter’s height and width.
- If the planter is round or has curved sides, use a flexible ruler or string to measure the curves and trace the shape onto cardboard before cutting.
Assembling the Mold
Once the cardboard pieces have been cut, you can begin assembling the mold. Follow these steps for a successful assembly process:
- Lay out the pieces of cardboard on a flat work surface to ensure the proper arrangement.
- Secure the cardboard pieces together by drilling pilot holes with a drill/driver and then fastening them with screws. This will ensure stability and prevent the mold from collapsing under the weight of the concrete.
- For round or curved planters, join the cardboard sections carefully, following the traced lines to create the desired shape.
- Reinforce any gaps or seams with duct tape to prevent concrete from leaking out during the pouring process.
By following these steps carefully and taking the time to create a well-structured mold, you’ll be able to create a large concrete planter that meets your specifications. Remember, the quality of your mold will influence the final appearance and durability of your planter, so take your time in this crucial stage of the process.
Preparing the Concrete Mix
Measuring and Mixing
To make a large concrete planter, start by selecting the right concrete mix for the job. An ideal choice is countertop mix or Quikrete, due to its strength and smooth finish. Measure the concrete mix according to the package instructions and pour it into a mixing container. Add an appropriate amount of sand to the mix, as this will improve the strength and durability of the planter. Using a shovel or a mixer, combine the concrete mix and sand until they’re thoroughly mixed.
Adding Water
Next, carefully measure the required amount of water to add to the mix. Be sure to follow the package instructions as the right water-to-concrete ratio is crucial for the strength and consistency of the finished product. Gradually add the water to the concrete mix while continuing to mix. It’s best to add water in smaller increments to avoid making the mixture too wet or soupy.
At this stage, the concrete mix should have the consistency of cooked oatmeal. If the mix is too dry, add more water sparingly. If it’s too wet, add additional concrete mix or sand until the desired consistency is achieved.
Once the concrete mix reaches the optimal consistency, let it rest for about 10 minutes. This rest period will allow the water to chemically interact with the cement, ensuring a successful final product. After the resting period, the concrete mixture will be ready for use in creating your large planter.
Remember to:
- Choose a suitable concrete mix, such as countertop mix or Quikrete
- Measure and mix concrete and sand according to package instructions
- Add water carefully and gradually, maintaining the proper ratio
- Adjust the consistency of the mixture as needed
- Allow the concrete mix to rest for 10 minutes before using
Pouring and Setting the Concrete
Applying Mold Release
Before pouring the concrete, it is essential to apply mold release to make it easier to remove the planter later. One common method is using a non-stick cooking spray. Simply spray the inside of the mold and the outer surface of the inner container (if applicable) with a generous coat of the cooking spray. The mold release will prevent the concrete from sticking to the sides and create a smoother surface on the finished planter.
Filling the Mold
For filling the mold, first, prepare the concrete mix according to the manufacturer’s instructions. Then, use a trowel or a shovel to transfer the concrete from the mixing container to the mold. Make sure to fill the bottom layer of the mold to the required thickness, usually around 2 inches (5.1 cm).
After spreading the concrete evenly as the bottom layer, place the inner container (or mold for the planter’s inner cavity) inside the larger mold. Carefully center the inner container and continue pouring concrete between the two forms, filling the sides of the mold. Use a trowel to distribute the concrete consistently and press it firmly against the sides of the mold to create solid walls.
Removing Air Bubbles
Eliminating air bubbles from the concrete mix is essential for two reasons:
- It ensures a smooth surface on the finished planter
- It prevents the formation of weak spots in the structure
While pouring the concrete, give the filled mold a few taps on the sides to help dislodge any trapped air bubbles. Alternatively, you can use a vibrating tool or wooden stick to gently agitate the concrete mix inside the mold.
After the mold is filled and the air bubbles removed, cover it with a plastic bag to keep the moisture in while the concrete cures. Allow the concrete to set and cure for the recommended time, typically 24-48 hours, before removing the planter from the mold.
By following these steps and using the right materials, you can create durable, large concrete planters that will enhance any outdoor or even indoor space.
Demolding and Finishing
Removing the Planter from the Mold
Once the concrete has cured, it’s time to remove the planter from the mold. Carefully follow these steps to ensure a successful demolding:
- Gently tap the sides of the mold with a rubber mallet or soft hammer to release any trapped air bubbles and loosen the edges.
- If the mold consists of multiple parts, carefully disassemble them one at a time. Be patient and avoid applying excessive force or pressure to avoid damaging the planter.
- Slowly invert the mold and gently lift it off the planter. If the planter is stuck, try running a thin, flexible blade, such as a putty knife, around the edges to break the seal.
Sanding and Sealing
After successfully removing the planter from its mold, it’s essential to smooth out any rough edges and imperfections. Follow these steps for sanding and sealing your concrete planter:
- Sanding: Using a fine-grit sandpaper, gently sand down any rough edges or high spots on the planter. Be sure to wear gloves and a dust mask for protection against concrete dust. Work systematically around the planter, checking for any uneven areas or imperfections. Remember to sand both the interior and the exterior surfaces of the planter.
- Cleaning: After sanding, thoroughly clean the planter using a brush or damp cloth to remove all dust and debris. Allow it to dry completely before proceeding to the sealing process.
- Sealing: To protect your planter and ensure its longevity, it’s important to apply a concrete sealer. Choose a sealer that works best for your specific planter, such as a water-based or a solvent-based sealer. Follow the manufacturer’s instructions for application, which typically involve using a brush, roller, or spray to evenly coat the surface. Allow the sealer to dry according to the recommended time and apply additional coats as needed.
By following these steps, you’ll have a well-finished and attractive concrete planter that’s ready to be filled with soil, plants, and your creativity.