Building Raised Beds For Gardening

I inherited my love of gardening from my mother and grandmother. I am a garden blogger, freelance writer, and Master Gardener emeritus.

Try out this easy DIY project for building a raised bed garden out of concrete blocks.

Image by René Bittner from Pixabay

How to Build a 4' x 4' Concrete (Cinder) Block Raised Bed: Quick, Easy, and Cheap!

Use concrete blocks to build a raised bed and fill it with good garden soil. It's quick and easy, and it lasts forever. A 4' x 4' raised bed is big enough to grow all the produce to make fresh spaghetti sauce and freeze or can a few jars for winter.

Note that the blocks are 7" wide and 9" long, so the bed will not be 4' x 4'. The block bed is 55" long. That works out to about 4 1/2'. That sounds OK, but the interior garden space is 3 1/3' or, about 40" wide on the inside. We built this to replace a wooden frame raised bed, and the concrete block bed has slightly less space.

The variety of shapes and designs available in concrete blocks may surprise you. Get creative.

Patsy Bell Hobson

How to Fill the Raised Bed

If you have some time to get the bed started before you plan on using it, follow these instructions.

First, cover the ground with layers of newsprint to kill any grass and discourage weed seeds. This newspaper or newsprint layer can also be recycled office paper or cardboard. Use what you have; even a thick layer of shredded paper will work. We also added the rotting boards from the raised bed that was replaced. The important thing is to overlay everything, so make sure the materials overlap. If using paper, make sure to have several layers.
Water down the paper.
Next, layer brown and green materials as you would when making a compost pile. Add more "brown" carbon-rich materials than green. To use "green" nitrogen-rich materials, apply thin layers of wet food and cover with dry materials.

Alternate Method: Mixing and Dumping

If all this crazy layering is like making lasagne and taking too much of your precious time, mix everything together in your wheelbarrow and dump it in the raised bed. Use the coarsest materials on bottom. Top with your premium soil to get plants off to a good start.

The purpose of the newspaper and cardboard is to block grass and weeds. We added the rotting lumber simply to recycle.

Patsy Bell Hobson

Green and Brown Compost Explained

"Brown" carbon-rich materials are shredded leaves, wood ash, straw, sawdust, shredded newspaper and wood chips.

"Green" nitrogen materials are fresh or green materials, such as kitchen scraps, coffee grounds, melon rinds, and corn cobs. Add apple cores, eggshells, vegetable peels, and that scary green thing in the back of the crisper drawer.

How to Collect These Materials

Grass clippings contain as much nitrogen as manure. A bed is best built a year ahead of using it. Start in the late summer and fall, when there is an abundance of vegetable scraps, grass, and leaves.

Keep a covered container for food discards in the kitchen during canning and preserving season. Ask coffee shops for grounds. Use the discards when cleaning your hair brush, dryer lint, paper towels, cardboard egg cartons, and nut shells.

Hauling all these blocks is a heavy job. It may take two trips in small cars.

Patsy Bell Hobson

If you are building a bed for immediate use, start the same way, with thick layers of paper, cardboard, and shredded office paper, and then water. I am replacing a bed that had good garden soil. That soil will go back into the new concrete block bed. I have compost and shredded leaves to mix in as well.

Starting from ground zero, use about 40% peat or core. Core has a few more nutrients, holds more water, and is less acid. Add moistened Canadian sphagnum peat moss or core into the raised bed. Stir in a combination of bagged topsoil, animal manure, sand, perlite, and vermiculite.
If you do use some garden soil, sterilize it first. This will keep you from transferring soil borne weed seed, insects, and disease into your new raised bed garden. Bake soil at 200° F on cookie sheets for 20 minutes, stirring once about halfway through.
Top the bed with your best enriched gardening soil for planting.
Enrich your "new soil" with a slow release fertilizer. Or, incorporate (N) "Nitrogen", (P) "Phosphorus" or (K) "Potassium", by adding (N) blood meal, (P) bone meal, and (K) greensand.

Other Additions to Nourish Your Raised Bed

Potting Mix Items: Materials that would normally be used to make potting mix can also be added to a raised bed. Additions to the soil include peat moss, vermiculite, sand, perlite, core, or compost.
Soil Supplements: Soil supplements are used to hold moisture, making the water available to the plants. These materials can lighten and aerate soil. Clay soil can benefit most from materials that hold moisture and lighten the growing medium.
Coir: Coir (coconut husks) is being marketed as a replacement for peat and as a soil amendment. It will also lighten up garden soil in raised beds or containers. Like peat, it holds moisture in the soil and improves drainage. Coir is a renewable resource. Peat comes out of bogs that took millions of years to create and is rapidly being depleted. Technically, peat is a renewable resource, but few of us have a million years to wait.
Scraps and Other Organic Matter: Bury food scraps, shredded paper, dust bunnies, and dryer lint while building the block bed. Be creative. Suitable organic matter includes those sad limp green things in the crisper and old, holey cotton socks.

Invite pollinators by planting things like nasturtium. Fill empty garden spaces with herbs and flowers to keep weeds out and attract pollinators.

Patsy Bell Hobsdon

What to Plant in the 5" Square Border Containers

Nasturtium, "Cup of Sun" tumbles over the edge of the raised bed in the photo above. Flowers in the garden attract pollinators and cover soil to prevent weeds.

I think the border of 5" squares in the concrete blocks are a bonus. Will the little 5" squares be hotter or cooler than the raised bed? I will experiment with a raised bed bordered with herbs.

I'll try the small "Spicy Globe" basil plants and little clumps of chives, parsley, chervil, cilantro, cutting celery, or the small "Signet Starfire" marigold.

Little Plants for 5" x 5" Spaces

Keep little plants spaces well weeded so they don't have to compete with weeds for water and nutrients.
Perennial Herbs	Annual Herbs	Flowers
thyme	chervil	marigold
chives	parsley	dwarf daffodils
tarragon	cilantro	calendula

This content is accurate and true to the best of the author's knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on June 16, 2015:

Right you are, coffee grounds are a great nitrogen source, great for composting. They can be added directly to garden as well.

Egg shells are more like a slow release calcium source, don't count on it for an immediate solution for calcium deficient soil. I would love to see your cinder block beds.

kimbrewaa on June 12, 2015:

I actually just put in two cinder block beds...great space and cheap too. I salvaged most of them from an abandoned house so yay me! Lol...but i think you may need to research your browns and greens again. Coffee grounds and spent tea bags are high nitrogen sources. They are great for composting piles...heats it up quick. Egg shells are a high source of calcium. These are great when you have a worm bin...aiding in digestion and reproduction. Great hub though!

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on April 05, 2015:

Favored, It would be a cute herb garden. Edible flowers, calendula, marigold, nasturtium will add color and attract pollinators. Have fun.

Fay Favored from USA on April 04, 2015:

OK, thanks. Might have to do this for a smaller bed like herbs. I can manage that myself. Thanks Patsybell.

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on April 03, 2015:

SusanDeppner, It is amazing how much food you can get in a small garden. I actually get more food from the small space, raised beds. The garden season is extended, intensive gardening and succession planting. Happy gardening!

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on April 03, 2015:

Favored, I do not suggest 3 high concrete blocks because of ground shifts and unstable garden soil. These heavy blocks could really hurt or scrape you up if they fall over.

I thought I would add a level, but after seeing how much they shifted over the winter, I changed my mind. It is easy to level up one layer in the spring.

A single layer will give you all the benefits of raised beds.

Susan Deppner from Arkansas USA on April 03, 2015:

I really like this idea! How fun to use the small square areas for herbs or small flowers. I'm hoping to add a second raised bed next year (I'm a very small-scale gardener) and this just might be the perfect plan. Thanks so much for the inspiration!

Fay Favored from USA on April 03, 2015:

I'm looking to raise our garden bed and was thinking about going higher with the blocks. Do you think they would be sturdy if I went 3 high? My husband can't do all the labor we had before so I need to come up with something that works for him.

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on January 18, 2015:

Glad to see you recycle. Thank you for reading my hubs

jeff1947 on January 18, 2015:

Now I can finally use all the leftover cinder blocks that used to be a book case

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on October 05, 2014:

You made my day. Thank you for reading my hubs. I have both wood and concrete raised beds. The wood can be made higher or deeper. Blocks are not as safe or successful. Do you grow tomatoes in the 4x4?

twodawgs on October 05, 2014:

Huh - cinder blocks, why didn't I think of that? I have a few 4'x4' boxes I've already built, but I may try the cinder blocks in another location. Lots of good info here, thanks!

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on August 19, 2014:

PegCole17, you can just dig a hole in you garden and bury shredded paper. Or, it makes great water saving, weed choking mulch. Thank you for reading my hubs. I appreciate it.

Peg Cole from North Dallas, Texas on August 19, 2014:

What a great idea to use paper shredding to line the garden bed. I have an abundance of that available. Thanks for these useful tips for small gardens.

Caren White on June 15, 2014:

Concrete blocks make great raised beds. The "holes" are where you can pop in your herbs. Good tip to layer the bottom to keep weeds from coming up. Voted up!

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on March 16, 2014:

DDE , thank you, you are kind. I would love to see your garden, when you do get around to building one. Raised beds give us a jump ahead on the gardening season, some times weeks ahead of our fellow gardeners.

Devika Primić from Dubrovnik, Croatia on March 16, 2014:

Great ideas for building a raised garden so simple and well put together. I enjoy reading garden tips and suggestions this one sounds helpful and convenient.

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on March 13, 2014:

MsDora , Any way I can help! I love sharing my passion. You can ask me any garden related questions. Love to help.

Dora Weithers from The Caribbean on March 13, 2014:

Patsy, there is hope that you will make gardener out of me. This is very useful. Thank you.

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on March 12, 2014:

I love hearing about other peoples joy in gardening. Thanks for reading my hubs. If you ever havegarden related questions, please ask.

JR Krishna from India on March 12, 2014:

I like anything about gardening.

Your idea of preparing a raised garden bed is excellent

Jackie Lynnley from the beautiful south on March 11, 2014:

This is great Patsy and I will start putting this in order this weekend if it doesn't turn cold again! Can't wait for that global warming! lol Up and sharing.

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on March 10, 2014:

Faith Reaper , You make my day. Those blocks are heavy. Take it easy and don't push yourself while you tote these concrete blocks. If you do get this done this spring, I'd live to see a photo. Thank you for your kind words.

Faith Reaper from southern USA on March 10, 2014:

Another excellent hub here as to building a raised bed! I like the quick and easy part too. You have given clear instructions and I may give this a try!

Up and more and sharing

Blessings,

Faith Reaper

Patsy Bell Hobson (author) from zone 6a, Southeast Missouri, USA on March 10, 2014:

Thank you. healthy meals. I think we should be working together Me growing and You preparing tomatoes.

Layering plant materials and making compost is like free fertilizer for you garden.

healthy meals from Europe on March 10, 2014:

I've seen that layering a few nights ago on a gardening tv program, seems to be very effective. I am happy I found your hub and had some of the green and brown compost terms explained.