Wood is the most often used material for building raised garden beds. Like everything else however, it has its pros and cons.
Before you can begin to look at costs, you have to determine whether you want to build with treated or untreated wood.
Pro and Cons of wood choices:
Untreated wood rots faster so you will probably have to rebuild your beds more often. How often will that be? It depends on the type of wood you build with. Some types are naturally more rot resistant like cedar or redwood. It also depends on the area you live in and where you build it. A bed built for shade loving plants will rot a little faster than one in full sun. A bed built on a concrete patio (without proper drainage) will rot faster than one build on well-drained soil.
Treated wood lasts longer but there are some concerns about the chemicals used to treat the wood. In 2003 the EPA banned the sale of wood treated with CCA (chromated copper arsenate). Before that time, treated wood was dangerous to use because CCA contains high amounts of arsenic. Today’s woods are considered safe by EPA standards; however, your crops cannot be certified organic if you use pressure treated wood.
How long it lasts. There are many factors to consider when attempting to estimate how long your bed will last. Pressure treated wood will probably last longer, but if your bed is in an area with higher soil moisture content, it may not last as long as unpressured treated in a drier area. My neighbor built with unpressured treated and had to replace after 3 years. He used 1-inch thick boards which of course rot faster than 2 inches, so that is a factor to remember. I have heard of untreated beds lasting 10 years. Pressure treated could last twice that much if you are not worried about the chemicals.
Planting on cement slightly tilted to ensure water runs off quickly would last longer than on ground that stays moist.
Cost can vary greatly depending on the area you live in. A 2-inch x 12-inch x 12-foot pressure treated pine in my area costs about $23. There are not any 2 x 12 cedar available in my area. The closest thing to compare it with is a 1-inch x 3-inch x 8 foot at $6.50. It would take 9 boards of that size to cover the same area as one of the pine and they are not pressured treated. However, cedar is naturally more rot resistant. There is not any redwood available in my area. It would probably have to be special ordered.
2-inch wood is not as easy to sit on as an 8-inch-wide block. That was a major deciding factor for me due to a bad back. I can sit for hours, hand picking bugs, suckers, weeds or anything else that needs picking when I can sit and do it. Bending over to do it and I don’t last 5 minutes.
Determining how much to buy.
Before you can begin to compute your cost, you have to decide how you want to build your garden bed. You’ll need numbers for how wide, long and high you want to go. If you are making it higher than a single board, I strongly suggest you make it in a multiple of the width of the board you want to use. If you use a 12-inch-wide board, make your bed 12, 24 or 36-inches high. For most people, it is almost impossible to cut even a few inches off a board down the entire length. Your cut will look more like a curvy road than a straight board, lol.
If you are going to make your bed longer than the length of your board, remember to add extra wood for additional up-rights to nail your boards to. You will need an up-right for both ends of the first board and both ends of the second board, plus one or more for the middle if your board is more than 6-foot long.
Based on the cost of the pressure treated pine in my area, it would take 9 boards at $23 each ($207) to build a 4-foot x 16-foot x 2-layer high bed. That cost does not include any up-rights or nails. Of course, your bed can be made whatever size you want it. Just compute your costs according to size.
Additional benefits of raised beds
You can usually plant a little earlier in raised beds because they warm up earlier than in ground.
You don’t have to plant in rows and can get more plants by using the square foot gardening method.
Soil remains less compacted so you do not have to till it. During the off season, cover the top with a layer of rotten compost material and some dried manure, then turn in to the top foot or so of your bed to keep mineral counts higher and the soil even looser. Loose soil promotes good root growth.
Few weeds and you’ll get even less if you cover your soil in a good layer of composting material while your plants are growing. This also helps to hold water in by prevent evaporation. Not matter how you are growing your plants, you should always use composting material to prevent water evaporation.
By lining the bottom of your bed with wire mesh you can prevent underground animals from burrowing up into your bed and eating your fresh veggies. Just make sure to buy a small enough mesh size to prevent whatever type animals you have in your area from coming through it. Around here, Home Depot and Lowes do not carry it, but Tractor Supply does.
If soil in your area is contaminated, a raised bed can allow you to grow crops you could not grow in the ground as they stay up and away from the contamination. Depending on what is in your soil, I would probably think about making your bed a few layers high to ensure the roots don’t reach into the contaminated soil.
Depending on the size of the dog and the height of your garden bed, it is possible to have a pee proof garden bed. Our boxer can hit over a foot high, but it really doesn’t matter because my bed is 36 inches high to help my back.
Remember, while the high bed is helpful with back problems, the higher they are, the more soil they take to fill. I was lucky when I built mine, my hubby was working for a dump truck company and he was able to haul it for free. But it takes a lot of soil to fill a 3-foot-high, 4 feet x 16 feet bed.
Some people swap out their soil every few years. I do not as every year I add additional manure and compost. Everything works fine for me. But I think I will probably have to take out a little soil in the next year or two. The soil level is raised slightly above the top level from the extra being added for so many years.
There is no 100% correct and only way to build a raised bed. It is what works for you, in the price and effort range you can put into the project. If someone doesn’t like the way it looks just tell them to turn their heads because it makes you happy and you didn’t build it for them.
That’s it for this time, please let me know if you can think of something you would like me to write about. Even if I have not tried it, I know how to research and compile data, so I’ll try to get it done for you.
Till next time, may you and yours be happy, healthy, wealthy and wise!
Love and Peace
From Denise