My last column discussed the nature of Raised Garden Beds (RGB), pros and cons, and construction materials. This column will focus on filling your RBG with soil as well as planting and maintaining it.
As an example, I will refer to the RGB I plan to install in my garden using an old wood picnic table for materials. I would like the bed to be at sitting height. The seats of our home chairs and couches are about 16 in high. I want thick side walls so I can easily perch on the edge. Also, I want to be able to reach into the middle and not spend too much on soil to fill it since this is an experiment.
Given the table pieces I have I plan to build my RGB 5 ft long by 32.5 in wide by 16 in high. The rim will be 2 in wide all the way around. Since the table pieces are all 8 in wide I will stack the side and end pieces 2 tiers high. I’ll use other materials to hold the pieces in place – probably wood uprights.
The wood from the table was treated on the tops at one time, but I think the treated material has mostly eroded off over the years. Even though it may not look as good, I think I’ll place the once-treated faces to the outside to avoid soil contamination. The way I have the bed configured it will need just under 18 cubic ft (about .69 cubic yd) of soil. I took a quick look online to get an idea of how much the soil will cost. While many places don’t stock top soil this time of the year I found in season prices ranging from about $1.30 to $3 per cubic ft (which is about 40 lbs). So I’ll be out about $23.40 to $54. This may be more arithmetic than you prefer, but I like to know price ranges.
So where will I place my RGB? This is very important since I won’t be to move it once assembled! The soil alone will weigh about 720 lb. Please consider the amount of sun your bed will receive on a summer day. If you’re growing vegetables, 6 to 8 hours are suggested. If you have other plants in mind, consider how much they will need. And don’t forget to factor in any shade from young trees that will mature over the years. Fortunately I have a very sunny area at the back of the yard.
I don’t plan to line the container with plastic and I won’t need to drill any holes in the bottom since it is soil. I mention this in case you plan to use a galvanized stock tank (drill holes in the bottom to avoid drowning your plants) or hay bales (you might want food-grade polyethylene to extend the life of the bales as they will decay more quickly if saturated with water).
Since I plan to use new soil, I won’t have weed problems right away. I may mulch with some compost on the top to help mitigate soil temperature and reduce water loss. I’m not a fan of using black plastic between rows of plants to cut down on weeds, but you may wish to do so if you’re using yard soil that may be weed infested. Just make sure the soil doesn’t get too hot in midsummer. In the area I plan to use I have a drip irrigation system on the ground and will modify it to water the RGB.
At this point, I’m planning to plant greens, basil, cucumbers, and squash (perhaps the vining plants can run over the side and onto the ground?). I think I will continue to plant tomatoes in the ground surrounded by water walls early in the season. I have plenty of strong tomato cages for use as the plants grow, but I do worry that our high winds could knock over tall plants starting 18 in above ground level.
Maybe you would like a RGB, but don’t want to build one. Try a stock tank. Or maybe consider a mobile RGB. At one time, I contemplated buying a waist-high unit on wheels that could be stored in a garage or other protected area and wheeled out during the day.
If you have experience with a RGB, I’d love to hear from you! I’m still dreaming about my new project.
“Winter is a time of promise because there is so little to do — or because you can now and then permit yourself the luxury of thinking so.” Stanley Crawford, A Garlic Testament: Seasons on a Small New Mexico Farm, 1992