Planter boxes are a great way to grow flowers, herbs, vegetables, and other plants outdoors. They elevate your plants off the ground, protecting them from pests while helping you tend them more easily. Building your own planter box allows you to customize the size, material, and design. With a few simple tools and materials, you can create a beautiful and functional addition to your outdoor space.
Choosing a Location
When deciding where to put your outdoor planter box, consider the following:
Sunlight
Most plants need at least 6 hours of direct sunlight per day. Evaluate your outdoor space and identify the sunniest spots.
Accessibility
Choose a location you can easily access for planting, watering, weeding, and harvesting. Near a hose or spigot is ideal.
Soil Quality
Avoid placing a planter box directly on concrete, asphalt, or other hard surfaces. The ground underneath should be a permeable surface that allows for drainage.
Size
Make sure the spot you choose can accommodate the size of the planter box you want to build. Measure the area to determine the best dimensions.
Aesthetics
Consider the look you want to achieve. Place the planter box in a spot where it can complement your home’s architecture and landscaping.
Choosing Materials
There are many options when it comes to building planter box materials. Consider the following:
Wood
Cedar and redwood are naturally rot-resistant woods ideal for planter boxes. Avoid treated lumber, which may leach harmful chemicals.
Plastic
Plastic planter boxes are lightweight. Look for UV-resistant plastic that won’t fade or become brittle in sunlight.
Concrete
Concrete planter boxes are durable and decorative but very heavy. Make sure you don’t need to move the planter box later.
Metal
Galvanized steel and powder-coated aluminum planter boxes resist rust. Ensure metal planters have drainage holes.
Bricks or Stone
Use brick, stone, or concrete blocks to create decorative planter boxes. Use construction adhesive between layers.
Composite Wood
Materials like Trex are made from recycled plastic and wood fibers. They resist moisture and won’t rot.
Tools and Hardware Needed
Before starting your planter box project, make sure you have the necessary tools and hardware on hand:
- Saw (circular saw, jigsaw, handsaw, or miter saw)
- Drill
- Screwdriver
- Measuring tape
- Level
- Square
- Hammer
- Wood glue
- Exterior wood screws or deck screws
- Finish nails
- Corner braces (for extra support)
Building a Wood Planter Box
Wood is a classic choice for building planter boxes. Follow these steps:
1. Cut the Wood
Cut your wood pieces according to the dimensions you want. The front and back pieces should be the same length. The side pieces should be the same length.
- Use pressure-treated wood or naturally rot-resistant cedar or redwood.
- Cut panels to the height you desire, accounting for the depth of the soil to go inside.
- Cut one or two panels an inch shorter to serve as divider strips if including multiple compartments.
2. Build the Box Frame
Assemble the front, back, and side pieces in a rectangular frame using wood screws or exterior wood glue and nails.
- Make sure corners are square using a carpenter’s square.
- Drill pilot holes to prevent wood from splitting.
- Don’t put a bottom panel on yet so excess soil can drain.
3. Create Compartments (Optional)
If including internal dividers in your planter box, now is the time to add them.
- Use divider strips to portion the box into different sized compartments as desired.
- Secure dividers with wood glue and finish nails.
- Dividers allow you to plant different flowers, herbs, vegetables, etc.
4. Attach Corner Braces (Optional)
For extra stability and reinforcement, use corner braces or angle brackets on the inside corners.
- Predrill brace holes to prevent splitting.
- Use screws to fasten metal brackets or wooden braces to box frame corners.
5. Apply Finish
Protect and beautify your wood planter box with an outdoor stain, paint, or clear protective sealant.
- Choose a non-toxic product safe for plants. Allow drying fully.
- Stain brings out the natural wood grain. Paint or sealant prevents water damage.
6. Add Bottom Panel
Once fully assembled and finished, flip the box over and attach a bottom panel.
- Cut bottom panel to fit dimensions of bottom frame.
- Drill drainage holes spaced evenly across bottom panel.
- Attach panel with wood glue and nails.
7. Move Planter Box into Place
Your wood planter box is ready for soil and plants! Move it into your selected outdoor location.
- Fill bottom with gravel for drainage before adding soil and plants.
- Consider putting the box on casters for mobility.
- Position box so drainage holes face away from the house or walls.
Building a Concrete Planter Box
For a permanent planter box that doubles as a landscape feature, build one from concrete using these steps:
1. Build the Mold
Build a wooden mold in the dimensions you want using plywood and lumber.
- Seal wood mold with caulk or plastic sheeting so concrete won’t stick.
- Make mold 2-3″ deeper than final planter height to allow for gravel layer.
- Coat inside of mold with vegetable oil or release agent.
2. Insert Drainage Pipes or Holes
Poke holes through the bottom of the mold using a stick or piece of rebar. Or insert short lengths of PVC for drainage.
- Space drains evenly across bottom of the mold.
- Holes or pipes prevent water from pooling under the planter.
3. Mix and Pour Concrete
In a wheelbarrow or mixer, combine concrete, sand, and gravel with water per package directions.
- Start with a dry mix and slowly add water.
- Pour concrete into mold 2-3″ deep. Use a stick to eliminate air pockets.
4. Allow Concrete to Cure
Let concrete fully cure for 1-2 weeks before removing mold. Keep it moist while curing.
- Drape plastic sheeting over concrete if needed to retain moisture.
- Test concrete hardness before removing form.
5. Remove Mold
Once fully cured, use pry bars and hammers to carefully detach and remove mold materials.
- Invert concrete box and set in place where it will reside in the yard.
- Hose off box to remove debris.
6. Seal the Concrete
Use a concrete sealer to protect and beautify poured planter boxes.
- Choose a non-toxic sealer rated for outdoor use.
- Use a foam roller or brush to evenly coat all concrete surfaces.
7. Add Drainage Layer
Line bottom of planter with gravel and landscape fabric before filling with soil.
- Fabric prevents soil from washing out through drainage holes or pipes.
- Gravel improves drainage so roots don’t get waterlogged.
Now you’re ready to fill your concrete planter box with soil and plants!
Common Materials for Raised Garden Beds and Planter Boxes
When building a raised bed or planter box for your garden, choosing the right materials is an important decision. Here are some of the most common options:
Cedar
Cedar resists rot, warping, and insect damage. It’s lightweight and easy to work with. Red cedar contains oils that naturally preserve the wood.
Redwood
Redwood is naturally decay-resistant and provides good insulation against temperature fluctuations. It’s durable and weathers to a silvery gray color.
Treated lumber
Lumber treated with chemicals provides weather resistance. Look for non-toxic treatment options, like copper azole. Avoid chromated copper arsenate (CCA).
Cinder blocks
Stacking cinder blocks is relatively inexpensive. Look for construction adhesive to reinforce the blocks. May not be decorative.
Plastic lumber
Plastic lumber, like Trex, won’t rot, crack, or require painting. Made from recycled plastic and wood fibers. Withstands weather well.
Poured concrete
Concrete offers a permanent, decorative option when built with forms. Disadvantages are weight and lack of portability.
Brick
Clay or concrete bricks are attractive and long lasting. Lay bricks over landscape fabric to help prevent sinking. Mortar is optional.
Stone
Building with natural stone has a pleasing aesthetic but takes more time and skill to assemble. Granite and limestone have good durability.
Galvanized steel
With anti-rust galvanized coating and wrapped edges, steel is strong, durable, and weather-resistant. Provides good heat reflection.
Frequently Asked Questions About Outdoor Planter Boxes
Building your own outdoor planter box is a rewarding way to grow landscape plants, herbs, flowers, and edibles. Here are answers to some commonly asked questions:
How deep should a planter box be?
A good rule of thumb is to make your planter box at least 12 inches deep. This gives adequate room for most plant roots to spread and grow. Deeper boxes between 18-24 inches suit vegetables and root crops best.
What is the best size planter box?
Planter boxes typically range from 2×4 feet up to 4×8 feet. Scale the size to your space and needs. Smaller boxes like 2×4 feet are good for patios and balconies. Larger boxes offer more planting flexibility.
Should planter boxes have a bottom?
Yes, it’s best to include a bottom or floor panel in a planter box to contain the soil and allow for proper watering. Drill drainage holes to allow excess moisture to pass through.
How long do wood planter boxes last?
When built with rot-resistant woods and proper construction, a wood planter box can last 5-10 years or longer. Use naturally durable cedar or redwood. Also apply wood sealants and finishes.
What can I use instead of soil in a planter box?
Mixing in compost improves drainage and nutrients. You can also try commercial potting mixes blended for containers and raised beds. Combining potting mix with compost or garden soil works too.
How do you secure a planter box?
Screwing planter boxes into deck boards or the wall provides stability. For railing planters, use strong brackets. Straps and mounting plates work on fences or posts. Place heavy planters on flat pavers or gravel.
How do you keep animals from digging in planter boxes?
The best defenses against animals are mesh screens over drainage holes, chicken wire fencing inside the box, and motion-activated water sprayers. You can also try scents that deter animals.
Conclusion
Adding a DIY planter box to your patio, balcony, or yard lets you grow flowers, herbs, vegetables, and other plants with ease. Choose from wood, plastic, concrete, and other materials to build a stylish container tailored to your space. Position your planter box in an optimal spot with sunlight, drainage, and accessibility. With simple tools and materials, you can build and install a planter box in a weekend. Maintaining good soil, proper watering, and protection from pests will keep your plants thriving in their new home. Get creative with designing a planter box that suits your gardening needs and enhances your outdoor living space.