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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.
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!
I ordered everything online at Home Depot for easy curb side pick up.
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.
The first things to consider when deciding how big to make your planter are:
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.
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.
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 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 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.
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.
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!
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.
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!
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!
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