This weekend Dan and I built a raised wooden vegetable planter and we are looking forward to the experience and benefits of growing some of our own vegetables this summer. I wanted to share exactly how we made our wooden planter to take some of the guesswork out of you making yours. This is a very simple project to complete but does require the use of some power tools. This post will teach you how to build a raised planter box.

---

To build a raised planter box you will need:

• a saw to cut the wood (powerful enough to safely cut a 4×4)
• a drill with appropriate drill bit for the screws

I decided to make one 4’x8′ planter that is 11″ high (I outline the many reasons for choosing this size below). If this size makes sense for you as well, this is the exact material that I ordered. However, if you are looking for a different size for your property you can certainly still use the guideline below to determine what is best for your site and make your own custom planter. That’s the beauty of creating your own planter – it can be whatever size suits your needs!

Materials to make one 4’x8′ planter box that is 11″ high:

• (1) 4x4x8 cedar post
• (6) 5/4 x 6 x 8 cedar boards
• #8 2 1/2″ wood screws (sold in a box of 100, 40 screws used to make this)

My Shopping Cart

I ordered everything online at Home Depot for easy curb side pick up.

---

1. Choose your Planter Location

When you are figuring out how to build a raised planter box, the first thing to do is decide where you will place your planter(s). Since your planter will be elevated, you will be bringing in fresh soil so choosing based on soil condition is not as important as if you were planting in the ground. The main factor to consider is sunlight. Most vegetables require full sun (6+ hours a day) to grow well. Monitor your property for a few days prior to building your planter to determine which location receives the best sunlight. If you are building this in the early spring before trees leaf out, make sure you consider the shadows that will be cast by trees once in leaf.

2. Choose what Size your Planter Will Be

The first things to consider when deciding how big to make your planter are:

1. how much space do you ideally require to grow what you are hoping
2. how much space you have to work with on your site
3. how high do you wish to make your planter so you can comfortably work in it and also prevent weeds (I suggest a minimum of 10″)

Once you have determined the ideal size for your planter(s) you can start designing the footprint by looking at the sizes of lumber available.

I decided on one 4’x8′ planter box that is 11″ high for a few reasons:

• 4′ is the width I have to work with before reaching a dense shadow for a good potion of the day (I’m dealing with a long and narrow passage between my house and our neighbour)
• 8′ lumber lengths would fit in my SUV to pick them up and would also be a good length for how much space I wanted
• 4’x8′ overall requires very few lumber cuts when using standard 8′ board lengths
• a 12″ height just needs two boards on each side – this height elevates the soil enough to prevent too many weeds and also keeps the planter cost reasonably low
• With a final area of 29 cubic feet, it’s the perfect size for one yard of soil

3. Choose the Wood for your Raised Planter Box

There are 3 main types of wood that you will find at your local hardware store. This may differ based on your geographic location, in Canada, these are our go-tos. If you go to a lumber yard you may have more exterior wood options.

Dimensional Lumber

The first wood you will come across if you search lumber will likely be dimensional lumber. This is very inexpensive and either spruce, pine or fir (not usually specified which). This is typically intended for indoor use and most commonly used to frame interior projects. When used outside this wood is susceptible to rotting and cracking more quickly than other wood varieties so its lifespan outdoors will be much less than other options. This would not be my suggestion for outdoor use but if it is what you have access to or what is within your budget then it is a great starting point, just bear in mind that it will not last as long.

Pressure Treated

Pressure treated is likely the next wood you will come across and this is made for outdoor use. It is the same woods as those above (spruce/pine/fir) but they have been treated with a liquid chemical preservative that is forced into the boards at a high pressure. This preserves them and make it so they are resistant to rot and pests and will last a very long time outdoors – it is the best option for framing of outdoor projects like decks. However, there are downsides to it as well. Because it is treated with a liquid it takes a long time (months) to dry out properly and often is installed before totally dry. In the drying process it can crack and shrink (if laid before dry it will leave gaps in your finished project as it dries and shrinks). Pressure treated is recognizable from its slightly greenish tinge from the treatment process but this weathers in time.

There has long been debate about the safety of using pressure treated wood for use with growing vegetables. My understanding is that the chemicals used to treat pressure treated wood have changed and improved over the years and they are now (in Canada, anyway) held to quite high standards and are generally considered safe. However, I recommend doing your own research further on this to make sure you are comfortable with them for your own vegetable growing.

Cedar

Cedar has, for a long time, been the go-to wood for outdoor projects (I am based in Canada, in the US it will vary geographically, Douglas Fir is a common comparable option in many parts of the US though). It is naturally rot and pest resistant making it a great choice. Also, it is a more environmentally friendly choice as it is a renewable resource and uses no chemicals in the process. This is my choice material if budget allows. For this planter the total cost of materials was $120 compared to about $80 for pressure treated. On a small scale project like this I found the cost difference easily justifiable but when it comes to larger projects like decks or fences the cost difference can be significant so both materials have their place.

Ipe & Other Hardwoods

If you go to a more vast lumber yard you may see other wood options such as Ipe which is a tropical hardwood from Brazil. It is a very strong wood that is long lasting, resistant to just about everything and starts out a really beautiful rich brown (ages to grey like everything else). It is quite a bit more expensive than cedar. In most cases I personally prefer cedar for my own outdoor projects because of the cost difference and the fact that it is a Canadian resource. However, Ipe is a very long lasting choice if budget allows and you love the look.

---

A Note: Nominal vs. Actual Size

When purchasing lumber, it’s important to note that the size of the lumber as stated (nominal size) actually differs slightly from its actual size when dealing with its width and height (not overall board length, that is accurate). For example, a 2×4 is a really common lumber size, the name 2×4 indicates that it is 2″ x 4″ x whatever length board you choose. However, the actual size is 1.5″ x 3.5″. The same sort of difference goes for most boards. For this project I used 5/4″x6″ boards which are actually 1″ x 5.5″. This mattered to me because I wanted the boards to sit flush with the top of the 4×4 posts in each corner. If I were going off of the nominal dimension (6″) I would cut the corner posts to 12″ to accommodate two 6″ boards and have 1″ of excess above the side boards. Instead, knowing that a 6″ board is actually 5.5″ I cut the corner posts to 11″ so that everything would sit flush.

If you are building something where precision is key, knowing the actual vs. nominal size is obviously super important. With this planter, the sizing is flexible so ultimately, if you had 1″ of post above your side boards…it’s not a big deal!

---

Wood Cuts required to make this planter:

• 4×4 post cut into (4) 11″ lengths and (1) 4′ length. 4″ waste approx. left over
• (4) 5/4x6x8 boards with no cuts to make the long sides, no waste
• (2) 5/4x6x8 boards cut in half to make the short ends, no waste

4. How to Build a Raised Planter Box – Putting it Together

You will need a drill, an appropriate drill bit for your screws, and your screws. If you are using different sized lumber for your corner posts or side boards than what I used then you will want to get the appropriate sized screws.

1. First, work on your short ends. Screw your first board in place so it is flush with the sides and top of your side posts. Next, put your second board directly below it. Do this for both planter ends.
2. With both ends made, you can add your long side boards next. Line the 8′ boards up with the boards on the short ends. Screw them to the corner post using a minimum of 2 screws.
3. You now have a freestanding structure! Add the 4×4 support to the middle of your planter. Attach it in the middle so that you can screw into it with both your top and bottom side board. This board is going to help keep your planter more square and reduce bowing on the sides.
4. Fill with soil! The planter I made is 32 square feet, but at 11″ high it is 29 cubic feet. A standard yard of soil is 27 cubic feet which will be perfect as it will sit an inch or 2 below the top of the boards.

Optional top cap: The image above shows an optional top cap (5/4x6x8 recommended with a mitred corner). When you have the end grain of wood exposed (like the top of your 4×4 corner posts) this area is susceptible to rot. Adding a top cap to cover that end grain prevents rot and also makes the planter look polished and complete. I opted against the top cap so that I had more useable space in the planter but I will consider adding one next year if I increase my planting area to two planters. Also, I just didn’t feel like doing it…if I’m being honest…ha!

---

So, What Now!?

Now that you know how to build a raised planter box and have put it together your planter is ready to use! Select a nutrient rich soil suitable for growing vegetables and begin growing in your new planter. Many people like to finish or seal wood when it is outside, I prefer not to as I simply haven’t found a natural looking stain or sealant that looks good after a year or two. All wood will bleach and change colour with the sun and that is the beauty of using a natural material. If, in a few years time, I feel like it is looking a bit too weathered for my liking I will consider staining or painting it a colour to match our house…but for now, I am going to enjoy the natural cedar colour as it weathers!

---