Raised Beds, Built Right
So you have done your research and are ready to go all in! That’s great news! Now it’s time to make a happy home for growing your food and maximizing your available land resources. There are many different planter designs to build from based on what your needs are, what building materials you have available, what you plant to grow, and what pests you are trying to eliminate.
This design is what I have installed in my own personal garden and it is used here as an inspiration for you to start from. Feel free to tailor it to your individual needs. My veggies and fruit are under constant attack from birds, squirrels, deer, racoons, moles, rats … every mammal in California. So the design here is a fortress, adjust accordingly.
If you have the resources for reclaimed materials, then I would highly recommend that. It is a great way to reduce and re-use. Just use caution for any materials that are “treated” with surface finishers, paints or protective coats that may break down into the soil. Where I live, the reclaimed “look” has exploded, driving up the market prices and made it cost prohibitive for my budget. So you will see that I used plain building lumber based on what I could afford. Depending on your budget, choose woods like redwood or cedar if possible. Now lets get started!
Typically, most raised planter beds are 12-18 inches deep. I prefer 18 inches to allow room for adding compost each year to improve the soil, room for root vegetables, as well as allowing for the use of a tiller to mix in winter cover crops (unless you are practicing a “no-dig” garden). These boxes are designed for the bottoms to be lined with metal fabric to keep ground rodents out. If it is too shallow, you will not be able to use a tiller safely without hitting the metal fabric at the bottom. The taller boxes will also require less bending which is a nice bonus.
This photo is your “tool list” plus the obvious shovel, rake and pick ax.
Determine the area and start leveling the ground first. Use a long 2×6 with a level to check for accuracy.
Measure out the locations for your post holes. Dig the holes 12 inches down.
Next, measure and cut the lumber to the dimensions of your planned box. Most raised beds are a minimum of 4 feet wide, and I would suggest no wider than 6 feet. This will allow you to reach to the center without having to step in the box and compact the soil. I made the boxes 8 feet long, enabling the use of standard lumber dimensions and eliminating extra cutting and waste. The first box is 6 feet wide and the other two boxes are 5 feet wide. Cut the four corner supports out of 4×4 lumber and measure 29 inches long (18 inch box height is really 17 inches with 12 inches to bury, remember that a 2×12 is really only 11.5 inches wide and and a 2×6 is only 5.5 inches wide).
Assemble the longs sides first. Measure a gap of 12 inches from the bottom of the 4×4 and make this mark on both sides around the piece for attaching both sides to the post, and then attach your first board using a square for accuracy. The bottom board is a 2×12 and the top board is a 2×6, screwed together with 3 inch long outdoor decking screws.
Once the bottom 2×12 is attached, place the 2×6 on top and screw together. If measured correctly, the top will be flush. Repeat for the opposing long side.
Now take the long, assembled sides and set them in the holes. Check that they are level and place a board across them and make sure they are level to each other. Small adjustments can be made once assembled, but it should be pretty close at this point to save any frustrations later.
Now take the bottom 2×12 piece that is cut for the desired width of the box and using clamps, hold it in place along the mark you made earlier that is 12 inches from the post bottom. This will provide reference of where this piece should line up. Clamp both sides across and screw together.
Now repeat with the top 2×6. This will go easier now that the box is supported. Now repeat process for opposing side.
As you can see in the pictures, the design places the posts outside of the box. This prevents the soil from contacting the supports and eroding them.
Now it’s time to check your handy work and make sure the box is level. Go around and check each side on its own, and see if there is a pattern or tilt to a certain direction. If so, raise the low side by adding a little dirt in increments to the low side and raising it until it is level
This part isn’t as important, but for extra credit, check for the box being square by measuring the diagonal distance and shifting the sides until the two diagonal measurements match. Take care not to push the box out of level. You may want to re-check that the sides are all still level.
Now its time to fill the post holes with dirt and get the ground inside the box nice and level. If you want to go the extra mile, fill the post holes with a small sized gravel to prevent the soil from directly contacting the posts and microorganisms breaking them down, preserving the support structure.
The metal fabric that was available came in rolls 3 feet wide and 25 feet long with 1/2 inch squares, so there will need to be two overlapping rows. Roll one row out and leave extra length (4-5 inches each side) to go up the sides of the box a bit and staple to inside of the structure using a standard staple gun, preferably 1/2 inch staples. Repeat for the other side.
Using 1 inch diameter schd 40 PVC pipe, cut 8 pieces that are each 12 inches long. Using 1 inch pipe straps, screw to the inside of the box at even intervals that match the opposing side so that they are flush with the top of the planter box. These will serve as the “sleeves” for the 1/2 inch PVC pipe to slide into, forming a nice support for bird netting or frost covers. By just bending a 10 foot piece of 1/2 inch PVC from one side to the other, you will make a dome, or you can construct a box design using 2-90 degree elbow pieces to produce a “U” shape that slides into the sleeves, allowing for taller vegetation.
To keep these from being accidentally pushed down, place an optional screw under the piece to keep it in place.
This the OCD side of me and optional. Remember the 80’s movie Caddyshack? I never want to deal with the ground vermin again, and I don’t want to kill them either, so to make sure they stay away from my food, I used metal wire to attach the overlapping metal fabric in the center. Once you fill it with dirt, the weight of the soil should be sufficient on its own.
Now take a step back and enjoy your new organic veggie fortress! These plants are now on lock down!
I have been amending this soil for two years, so it is freshly tilled and ready to add with some additional organic compost to mix in as I fill up the boxes. Most of the weeds and roots have been removed. If you need to, this is the perfect time to amend the soil and correct the Ph. The first thing that will be planted is a cover crop to fix the nitrogen in the soil and suppress any further weed seeds that may germinate in the new box. The cover crops will also add some nice organic content as well.
The next step will be to run drip irrigation to the boxes, a topic that will be saved for a separate post. I installed a landscape fabric around each raised planter box and stapled it to the box itself and covered with mulch to suppress any further weed growth outside the boxes to reduce future labor and prevent any erosion.
I hope this serves your needs well and addresses some of the future problems you may encounter, reducing your frustrations and improving your organic successes!