Can you put a planter box on concrete? | 4 Ways to prepare your planter box

You can put a planter box on concrete if you cover the drainage holes with mesh or geotextile, protect the concrete from water and choose the correct soil for the planter. Making sure your planter has drainage by raising it off the concrete, catch any water run off using a saucer and use a good quality raised garden bed mix.

How to put a planter box on concrete

Putting your planter box on concrete maybe the only choice in a small yard, if you have a large, paved area or live in an apartment.

The top 4 things to remember when placing a planter box on concrete is to protect the drainage holes to keep dirt off your concrete, ensure proper drainage, catch the excess water and choose the right soil.

Here is everything you need to know to successfully grow your plants and protect your concrete base.

Raised planter boxes are fantastic for growing vegetables throughout the year.

How to prepare your planter box for concrete

To prepare your planter box before placing on your concrete you will need to find a way to capture water that will drip from drainage holes, prevent soil from flowing through to the concrete and hold it al in place.

1. Keeping dirt off your concrete

To keep dirt off your concrete use wire mesh to cover the drainage holes inside your planter box before filling it with soil. Use insect wire with small holes to cover the drainage holes which will catch most of the soil pieces. Use a staple gun to hold the wire in place to prevent it moving when you fill the planter box with soil.

Here are some pre-cut wire mesh covers from Amazon.

Geotextile fabric is another way to prevent soil from flowing through the drainage holes onto your concrete. Layer the fabric on the bottom of the planter box to cover the holes and hold soil in your garden bed. This can be used in combination with the wire mesh to provide the best barrier to prevent soil escaping onto your concrete.

2. Drainage

Drainage is the most important factor to consider when placing a planter box on concrete. Raising the garden bed to allow drainage will avoid water pooling in the bottom of your planter. Raising the planter box using pot feet or movable trays with wheels.

3. Catch the water

To catch the water that drips from the planter box drainage holes and prevent it from marking your concrete use some pot trays. Saucers or pot trays are usually placed underneath indoor or outdoor pots to catch water. These are thin so will easily fit underneath your planter box on wheels.

Check out these Terracotta pot trays from Amazon.

4. Choose the right soil

Choosing the right soil for your planter box is a very important factor to improve plant growth and make sure it won’t flow straight out of the holes. Planter box soil is specially mixed to avoid compaction.

Planter box soil mixes are available from Amazon, nurseries or from landscape suppliers. They are perfectly designed for this purpose as this will contain a mix of compost, sand and fertilizer.

The balance of sand and organic matter will prevent it from compacting too quickly.

Planter boxes can grow flowers, succulents herbs or vegetables on concrete.

For more on this, check out my previous article on how to fill a planter box.

How to place planter boxes on wheels on concrete

Planter boxes on wheels have the added benefit of already being raised off the ground. This will allow water to naturally drain out of the bottom of the planter to avoid root rot on your plants. Without proper drainage the planter box can capture water inside and form a soggy pond which will damage the soil and plants.

If your planter box is not on wheels, check out these plant caddies from Amazon. These can raise planter boxes and allow them to be moved easily.

How many drainage holes to put in planter boxes on concrete

Large planter boxes that are anywhere from 3-5 feet long will need at least 3 drainage holes. Placing 1×1 inch drainage hole every 1 foot in the bottom of your planter box will help to prevent water pooling in the bottom.

These are usually pre-drilled in concrete planter boxes. Wooden planter boxes are easy to drill additional holes if needed.

Drainage holes for planter boxes on concrete

Planter boxes will need drainage holes even if they are placed on concrete. Raising the planter box slightly using pot feet or pavers will be essential to ensure that the water can escape out of the bottom of the planter.

Wooden, concrete or stainless steel planter boxes will all need drainage holes to avoid capturing water in the bottom of the planter which can rot the roots of your plants.

Growing your own food in a planter box on concrete

Planter boxes are the best place to grow your own edible garden. This could include herbs, strawberries and vegetables. Plant your tomatoes together with basil and create a great garden that will work well in salads.

I have successfully grown both summer and winter crops in planter boxes. Add extra composted cow manure and pelleted chicken manure when you are ready to rotate your crops. Dig it through and allow it to settle for 2 weeks before planting.

Concrete staining and planter boxes

To prevent any staining on your concrete or pavers underneath your planter box, use the method of catching any water drips with pot trays. Make sure you empty out the pot trays regularly otherwise any overflow can still stain your concrete.

As the water flows through the soil it will pick up color from the dirt and can create brown stains. If this happens, don’t worry, they can be easily removed with a pressure cleaner.

Can you put a planter box on concrete? | Summary

Planter boxes can be placed on concrete but they work best if they are raised and you implement a method to catch any water flow. This can be done using pot trays or any low laying container that will fit under your planter box. Line the planter box with geotextile and mesh to hold the soil in.