Great Big Garden Bed for Growing Giant Carrots

Introduction: Great Big Garden Bed for Growing Giant Carrots

Spring is here and it is time to start planting the garden. A few months ago, a favorite seed store advertised that this year they are selling seeds for giant carrots. These things can apparently get up to 3 feet long: what fun! So, I bought the seeds. Of course, the problem with carrots that can get 3 feet long, is that you need a place to grow carrots that are 3 feet long. While I like to think the soil in my garden is pretty good at this point, I certainly do not have 3 feet of loose, fertile soil. So that is the purpose of this project: to build a garden bed that can hold giant carrots and encourage them to grow!


Scrap Wood (24 2 1/2 ft 1"x4" sections and 4 2 1/2ft 2" X 2" sections)

Screws (1.5" - 2" screws will be ideal)


Carrot Seeds

Coconut Coir



Step 1: Determine How Big You Want Your Raised Bed

These carrots can reach sizes up to three feet long. The company that sells them says they use a 4ft deep raised bed to grow them, so if you are going for perfect, you probably should too. For my purposes, I did not want to fill a 4 foot deep raised bed, and I am more than excited if I get a 2 foot long carrot, so I built a roughly 2 and half foot tall bed. If however, you want to build an even bigger raised bed, you can follow the same steps here, but just increase the length of your corner posts and the number of boards on each side.

Step 2: Source Your Wood

If you have not noticed, wood prices are out of control. A rapidly expanding housing market, home improvement projects, and limited supply of lumber have driven the price of wood way up. So, rather than getting new wood from the store, consider getting old wood from somewhere else. In my case, I found a posting on Craigslist for old decking that someone was replacing and wanted to have hauled away.

(I will pause for a moment because I know that some of you may be gasping - old deck wood for a food garden? Yes, deck wood was almost certainly pressure treated, and yes this wood also had been painted, so someone who is an organic gardening enthusiast may want to opt for another option. But for my purposes, this wood should do just fine).

Step 3: Cut Your Wood

I cut my 1X4s into 2 1/2 ft sections. I also had obtained some 2" x 2" poles with the decking material, which I cut into 4 separate 2 1/2 ft sections.

Step 4: Screw the Initial Boards Together

The basic design we are going for is four walls of 6 1X4 sections built around 4 corner poles cut from the 2x2 poles. By using the poles, it gives something solid to screw into, allows the cutting on the edges of the boards to be very rough (which is great for scrap would), fortifies the corners, and gives an anchor to go down into the ground.

Start by lining up one edge of a 1"x4" section with one of the 2"x2" sections. Make sure it is flush with the edge of the pole, and that the outside edge of the 2x2 is perfectly perpendicular to it. You are establishing the angle for the whole side with this first board. To be exact, you can use a square to make sure a 90 degree angle is made between the pole and the board. Repeat this with 5 more 1"x4" boards. You will notice that part of the 2"x2" board will still remain uncovered. This is ok, when we flip over the container, it will be something of a foot that we can lower down into the existing soil and help level the garden bed. Now we have aligned one side of the raised bed, let's attach the other 2"X2" to the other side.

Step 5: Build the Next 2 Sides

Now, we can attach the next side to the corner by adding 6 more 1X4 sections in the same manner. Decide on which side you wish attach to the existing corner, and then add the third 2"x2" section to the opposite side of those boards; connecting them to the pole just as you did with the first side. You can now place that side on the ground and screw the corner piece of the first side you completed down into the 6 1X4s becoming its opposite corner piece as well. You can add the third side in the same manner.

Step 6: Build the Final Side of the Garden Bed

And then we can screw in the final side to the two uncovered corner pieces. I recommend flipping the entire container onto its back (completed) side to make this easier.

Step 7: Put Down Cardboard

Great, the actual bed has been constructed! To help prevent weeds from growing up into your bed, I recommend putting down enough cardboard to cover the entire bottom of the bed, plus some additional cardboard to stick out a bit on the edges and prevent weeds from growing.

Step 8: Now, Let's Level Our Bed

The most annoying part of putting in a raised bed is getting the soil under it to be level. In this case, we have left ourselves some legs sticking out on one side of our bed. We can use these legs to help level the raised bed without getting all the soil below it level.

Cut your cardboard at the locations on the four corners that you intend to place the garden bed legs. Also if you are installing the bed on a day the ground is wet and muddy, it may help to push the legs of the bed into the soil. If not, you may want to dig small holes where the legs are going to be installed. Now get out a level and push down each leg to an appropriate depth that the level is level. You can now back fill with soil. I also suggest pushing soil against any gaps that might be present between the bottom of the bed and the ground.

Step 9: Fill the Raised Bed With Sand, Coconut Coir and Compost

To successfully grow giant carrots one of the most important things is having loose, well draining soil. Some giant carrot growers even grow in full sand (and then water with nutrients). In our case we are also using a lot of sand. If you happen to have an old sandbox around, this is a great time to clean it out and replace it with new clean sand while using the old stuff in your carrot box. If not, just go ahead and go buy some sand. I recommend at least 300lbs of play sand. I also mixed in three coconut coir blocks. Coconut coir helps the soil to retain some moisture and is made from the outside of coconuts. Many prefer coconut over peat moss as it is a more easily renewed resource. If you have not used coconut coir before, it frequently comes compacted and dehydrated in a hard block. You add warm water and let it soak it up, and then eventually it becomes a nice loose rich consistency. Many seed starting mixes have a lot of coconut coir. Note; however that professional giant carrot growers likely would skip the coconut coir as carrots grow faster when they are reaching for water. Finally I suggest adding compost to your soil. You can make your own compost, or get it from a store pre-made. Many municipalities also provide it to citizens free or for a low price.

Step 10: Plant You Carrots

I left the top layer of carrot bed as pure coconut coir, so it can hold that moisture and help the carrots germinate. Another cool tip to germinating carrots: cover the seeds with something to trap in the moisture. In this case, I used a large sheet of cardboard to do the trick. Take the cardboard off as soon as the seeds have germinated. And now we have carrot seedlings!

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    8 months ago

    Yay! I'm curious to know how the carrots grow :D


    Reply 8 months ago

    Thank you, Jessy. I will make sure to post an update in these comments in a few months!