Building Raised Garden Beds from Concrete Blocks: An Affordable and Durable Solution

Raised garden beds made from concrete blocks offer a simple, durable, and budget-friendly way to build productive gardening spaces. As opposed to traditional in-ground gardening, raised beds provide many advantages that make growing vegetables, herbs, and flowers easier for the home gardener.

In this comprehensive guide, we’ll explore the benefits of using concrete blocks for raised garden beds and provide step-by-step instructions to create your own.

Why Choose Concrete Blocks for Raised Beds?

There are several excellent reasons to select concrete blocks when building raised bed gardens:

Durability – Concrete blocks are extremely sturdy and durable. Unlike wood or other materials, concrete block raised beds will last for many years without rotting or deteriorating.

Affordability – Concrete blocks are an affordable option compared to materials like brick stone, or decorative wood. They can often be found cheaply on sites like Craigslist and Freecycle.

Design flexibility – Concrete blocks allow for countless design possibilities. Beds can be any length, shape or height. Blocks stack and arrange easily to create custom beds.

Pest deterrent – The solid concrete walls act as a barrier to burrowing pests like gophers and moles Rabbits also have a harder time accessing plants

Weed prevention – Concrete blocks prevent weeds from surrounding areas encroaching into the garden bed.

Convenience – Built-in “pockets” in many concrete blocks are perfect for additional planting, trellising or adding hoop structures.

No chemicals – Plain concrete blocks don’t leach chemicals into the soil. They are safe for edible gardens.

Raised Bed Designs with Concrete Blocks

One of the best features of building raised beds with concrete blocks is the creative flexibility. Garden beds can be designed in straight rows, squares, L-shapes or any geometric layout. The modular blocks make constructing unique multi-level beds simple as well.

Some popular design ideas include:

• Single layer blocks for shorter beds
• Double or triple stacked blocks for deep beds
• Mix of full blocks with half blocks for staggered, interlocking patterns
• Incorporating decorative concrete caps or corner blocks
• Contrasting block types and colors for visual interest
• Square foot gardening layouts work well with concrete block beds

With concrete blocks, you can create raised garden beds in any shape or size your space allows.

Step-by-Step Instructions for Building Concrete Block Raised Beds

Constructing your own raised bed from concrete blocks is straightforward. With a few tools and materials, you can build a bed in a weekend:

Supplies Needed

• Concrete blocks – Calculate quantity based on bed dimensions
• Gravel or crushed rock – For leveling the base
• Sand – Helps fill gravel gaps
• Landscape adhesive – Optional, for securing stacked rows
• Topsoil – For filling the bed
• Concrete surfacer – Optional, for capping block finish

Tools Needed

• Tape measure
• Shovel
• Level
• Wheelbarrow
• Trowel
• Hammer
• Chisel
• Gloves, goggles, mask

Instructions

1. Plan layout – Measure area and map shape/size of bed(s). Calculate blocks needed.

2. Prepare site – Remove grass or debris. Level ground surface.

3. Add gravel base – Spread 2-4” thick gravel layer. Top with thin layer of sand.

4. Arrange blocks – Place first row of blocks end-to-end on gravel base. Check level often.

5. Stagger blocks – Offset second row from seams below. Use adhesive between layers if desired.

6. Check level – Use level tool frequently to keep blocks even. Adjust as needed.

7. Repeat stacking – Continue adding rows to desired height, alternating direction.

8. Optional – Coat blocks with concrete resurfacer for smoother finish.

9. Add soil – Shovel topsoil into beds. Mound 2-3” below top edge.

10. Plant! Enjoy your new raised bed gardening space. Amend soil as needed over time.

With the right materials and tools, building raised beds from concrete blocks is totally doable for the DIY gardener. Focus on keeping the structure level as you stack the modular blocks. Then fill with fertile soil and get growing! Properly built, these affordable concrete block beds will provide many seasons of productive gardening.

Common Questions about Concrete Block Raised Beds

Are concrete blocks safe for raised garden beds?

Yes, plain concrete blocks are safe. Avoid blocks containing fly ash or other toxic ingredients.

How many blocks are needed for a 4×8 raised bed?

For one layer high, figure around 16-20 blocks for a 4×8 bed. Double for two layers high.

Should beds be lined before adding soil?

Adding a weed barrier inside can help soil stay in place. Avoid landscape fabric on the bottom as it can block root growth.

How thick should the soil be for planting?

Around 12-18 inches of soil is ideal for most vegetable plants. Concrete blocks allow for deeper soil than typical raised beds.

How much soil is needed to fill a bed?

An 18-inch deep 4×8 bed needs about 2.5-3 cubic yards of soil. Deeper beds or larger sizes require more soil.

Should the blocks be glued together?

For freestanding beds under 2 feet, gluing or mortaring is not necessary. Stacking alternated rows helps blocks interlock.

What can be planted in the holes?

The built-in pockets are great for smaller veggies like herbs or lettuce. They also work for vertical gardening by inserting trellises.

Do the beds need a foundation or gravel base?

A 2-4 inch layer of gravel helps provide drainage and prevent sinking or shifting of the first block row.

Building your own raised bed from concrete blocks is an easy and affordable DIY gardening project. Follow the basics steps, and with a little planning and elbow grease, you can create durable raised garden beds that will provide many years of gardening enjoyment.