You know you need to keep your bonsai outside. You’ve considered the light and wind. But now what? Do you just sit them on the ground?
Ideally bonsai should be kept off the ground to allow for better drainage and to reduce the risk of pests or disease moving into your pots. It also isn’t particularly easy to get a good look at bonsai sitting on the ground. Being able to easily see your trees helps you monitor them closely at all times. For these reasons at a certain point many bonsai enthusiasts will build bonsai benches, stands, or shelves to showcase their treasures.
If you’re interested in taking the plunge and building a bonsai bench know that they are mostly custom jobs, and for good reason. Your first consideration is location – where you plan to place the bonsai bench. Consider light, wind, and ease of use: where you’ll be able to view or work on your trees. Next you’ll consider shape and size. As you cannot properly see one bonsai behind another, benches are frequently very long and thin or have multiple steps or layers.
If you have carpentry skills you can build a fancy bench, but plenty of benches consist of simple wooden boards and concrete block. My first bonsai bench was a couple of 8-foot long 2x4s on single concrete blocks. It was small and crude but at the time it did the job. Having moved to a new home with a proper yard, I was in need of a bonsai bench of some sort and wanted one that was a step up (pun completely intended) from two wooden boards laid on the ground.
In building a basic outdoor bench, make sure to use pressure treated wood. Pressure-treated wood is treated with chemicals to resist decay and bugs. Not only will it hold up to the elements better than its untreated counterpart, but also it will develop a great aged look after time.
On my bench I used 2×4’s for the frame and then added 1×4 top boards to use as the table top, keeping a ½ inch gap between the boards. You can make the bench one level or multiple. I only had two levels to keep the bench fitted with the house below a window. I found the best way was to make each level on its own instead of one large interlocking bench. This method makes it much easier if you have to move or repair any part of the bench. I rested the bottom level on cinder blocks so it’s about 6-8 inches off of the ground. If you want a bench that’s higher up I would suggest using 4×4’s as legs. If you were making them higher then 3 feet I would add a bracing bar on each side connecting the two legs about halfway up.
My bench begins close to the ground. So as to reduce leaves from blowing and collecting under the bottom and disincline bugs and pests from living there we built a rock trench below it.
To build the rock trench, first the ground was smoothed flat. A tamper could be used but isn’t necessary, this can be done with a shovel or just your feet. After spraying Roundup to kill any weeds or vegetation under the bench, a weed barrier was spread to prevent weeds and bugs. The tarp was tamped down with stakes called fabric pegs. I used about 15 of them. The tarp for the weed barrier was the same size as the outline for the rock trench. I used the 3 / 50 from Vigoro from Home Depot, but it’s the same as this product. (They seem to have Vigoro on Amazon but it doesn’t qualify for prime shipping.)
After the tarp is secured with stakes, pressure treated landscaping timbers were laid on top. They come in eight-foot lengths and I used two of them. We used three sides, the front six-foot, and the sides four feet each making an outline of sorts. You don’t want wood against the house. Moisture retained by the wood can cause mold on the concrete (or worse if you have wood construction on your house). Just three sides to outline your trench will work just fine as the house closes the structure naturally. If you don’t have the saw to cut the lengths yourself, they will do it for you at Home Depot, provided you pay for the full length of the wood. Rocks were used to fill in the space on top of the weed barrier. I used white marble chips, seven bags worth. To know how many bags you will need, multiply the width times the length of your landscape timbers to determine your square footage. So if you are making a 4 x 6 rock trench you have 24 square feet of space to lay rock. Product instructions on the bag for the marble chips or rock should tell you how much square footage the bag’s worth will cover. No nailing, screwing or joining of any kind was done on the rock trench.
My bonsai bench does require carpentry skills, but also employs use of cylinder block. Consider in your design if you favor small (Mame) bonsai you can move with one hand or large (Dai) bonsai it takes four-hands to move. Larger bonsai specimens can be quite heavy and require support accordingly.
Overall, the rock trench cost about $60 I supplies and took about two hours to put in. The bench was about $85 and took about five hours to put together, including doing the sawing here myself.