Wooden Garden Troughs

Adding green growing things to any living space just makes it more livable. Interior decorators and workplace designers figured this out long ago. That’s why we see huge planters in shopping malls and office foyers. It’s also why many people like having plants growing in and around their homes. Besides the beauty of the flowers and green plants, we can also grow much tastier produce than what’s found in the grocery store.

While it’s possible to plant anywhere there’s dirt, just spading up a portion of your yard and trying to turn it into a garden doesn’t always work out all that good. That patch of garden will probably have grass trying to grow back up in it, along with weeds and some insects that might not be beneficial to the intended plants. Besides that, the soil around most homes isn’t the best for gardening purposes.

For these reasons, many gardeners or would-be gardeners have turned to either raised bed gardens or using garden troughs. Either one provides the benefits of being able to use better potting soil, allows for better drainage, keeps from packing the dirt down and lowers the chance of weeds.

So, what’s the difference between a raised bed and a garden trough? The raised bed is a box that sits on the ground. It usually doesn’t have a bottom, using the ground itself as the bottom. Landscaping fabric or poultry wire may be placed in the bottom to keep weeds, grass and burrowing pests out, but it’s essentially a vertical extension of the ground around it, albeit filled with a much better potting soil. On the other hand, garden troughs have a bottom, providing a physical barrier between the planting area and the ground. That does a better job of keeping out the weeds, grass and burrowing pests. It also allows the garden trough to be set on a deck or concrete patio, something that can’t be done with a raised bed.

Basic Design Criteria for a Wooden Garden Trough

Wooden garden troughs can take on a wide variety of different styles, can be made in literally any size and can be made out of a variety of different types and shapes of wood pieces. But there are a few things they all must have in common, in order to be effective. There are also optional things that can be considered in designing one.

Wood

To start with, the type of wood selected for the garden trough is important. Most wood begins to decay, when it becomes wet. Being in contact with dirt can add to this, both because the dirt will help hold moisture up against the wood and because the dirt will provide a pathway for bacteria, fungi and wood-eating insects to get to the wood. “Dry rot” which is a common problem for door frames, especially garage door frames, is actually caused by a fungus that is activated when the wood soaks up water from the ground.

The key to eliminating or at least reducing rot and other water-related damage to the garden trough is in wood selection. Some types of wood withstand damage due to water and the various wood destroyers that need a moist environment. Amongst these is cedar, redwood and of course, pressure-treated lumber.

Assembly

It’s important to understand that the garden trough will be supporting quite a bit of weight. One cubic foot of potting soil can weigh anywhere between 75 and 110 pounds, depending on the specific makeup of the soil and how moist it is at any one time. This means that a garden trough that is 4’ long, 1’ wide and 1’ deep could easily be holding 440 pounds of soil; and that’s not even a large trough.

One of the basic design principles that many people adhere to is to avoid allowing any end grain to show in the finished project. While that is not a requirement, if it is desired, it will be necessary to create mitered corner on any corner boards or top frames of the garden trough.

Drainage

Drainage is of critical importance. Overwatering of plants is a sure way of killing them. But so is not giving them enough water to drink. The solution is to overwater them, while providing drainage for that water, so that the excess can have a means to leave the garden trough. Flower pots usually have hole in the bottom for this purpose and a garden trough needs the same.

Legs

Legs are not a requirement for garden troughs, although many have them. Adding legs is more than a decorative decision, as putting legs on a garden trough raises it up to a height where gardening can be undertaken, without the gardener having to stoop of kneel. That can be especially important for elderly gardeners who may not have the agility they once did.

But legs also help with protecting the plants in the garden trough from subterranean pests and weeds, as there is a gap between the soil in the trough and the ground. While this doesn’t help protect the plants from airborne pests, it does protect them from man of the most troublesome ones.

Keep in mind that this means that there’s not going to be any natural migration of helpful subterranean critters from the ground into the soil in the garden trough. It might be necessary to add worms and beneficial insects to the biosphere of the garden trough to help keep the plants and soil healthy.

Soil

Using the soil available from the property around the home can eliminate the advantage of planting in a garden trough. While it is an extra expense, buying good potting soil from the local garden center can help make the overall project a success. It’s really a rather small investment for the potential payback.

Making a Low-Cost Garden Trough

To make a low-cost garden trough, it helps to start out with low-cost wood. Some of the cheapest wood available in the lumberyard is cedar fence pickets and 2”x 4”s. While the 2”x 4”s aren’t really protected from moisture, we can protect them by covering them with some sort of an oil finish. That will help the cedar as well, although it is not absolutely necessary.

A full 2”x 4” isn’t required for the framework, so to make the garden trough’s framework, start by ripping the 2”x 4” in half, making it into what is essentially two 2”x 2”s. Those will provide enough thickness to attach the cedar boards to and provide sufficient strength, without taking up too much space on the inside of the trough.

The overall height of the trough will be the height of the planter box, plus the height of the bottom of the planter and the height of the legs. So if we want a 12” tall planter on 6” legs, we’re actually going to end up with corner pieces that are 18” long. That will provide 12” for the planter, 6” for the legs and 2” for the bottom (1-1/2” of frame and ½” of cedar stakes for the floor).

Cut the legs, and then cut two sets of pieces of the 2”x 2” to go between them, forming the bottom and top of the planter box. So, for a 3’ x 1’ planter, 1’ tall, with 6” legs, the cut list will be:

  • 4 pieces 18” long for the legs 
  • 2 pieces 33” long for the upper and lower frames on the long sides
  • 2 pieces 9” long for the upper and lower frames on the short sides

In addition, there will need to be pieces of the fence pickets cut to cover the sides and the floor of the planter.

  • The long side pieces will need to be 36” long 
  • The short side pieces will need to be 13” long
  • The pieces for the floor of the planter will also need to be 12” long, with the ones on the ends notched out for the legs

To assemble the planter, start by laying out the framework for one of the long sides. This will consist of two of the legs, along with one of the longer frame pieces. They should be laid out to form a capital “H,” leaving 12 ½” of space above the crossbar and 6” of space below it. Attach the pieces together with 3” nails or screw. Don’t worry that it is not stable; adding the fence pickets will stabilize it.

Cover the side of the planter with 36” long pieces from the fence pickets, working from the top down and putting the pieces up tight against each other. Make sure that the framework stays square as these are being attached and that the ends of the cedar pieces are flush with the ends of the frame. It will be best to use 1-1/4” decking screw to attach them. The last piece to be attached will probably need to be ripped to make it fit flush with the bottom of the crossbar, leaving the legs hanging below. Repeat to make the other side.

To attach the two sides together, it is best to install the top piece of cedar onto both ends, connecting the two sides together. First screw it to one side, and then attach the other. The ends of the cedar for the ends should overlap the ends of the cedar for the sides, making a flush corner. Then, with the first piece in place to stabilize the two sides, add in the 9” end frame pieces, aligning them with the longer H crossbars. Attach them with 3” long nails or screws, just as the longer pieces were attached. Finally, add additional pieces of cedar to finish out the ends, just as it was done for the sides.

The next part to be installed is the floor of the planter. These pieces should be spaced ¼” apart, providing a drain for excess water to drip out of the planter. Besides notching out the corner, it may be necessary to rip one board, in order to make them fit.

Next we’ll add some additional battens at the corner. They really won’t add any additional strength; but will make the planter look sturdier. To avoid mitering these pieces, rip a fence picket so that one side is ½” wider than the other. The two pieces can then be tacked onto the two sides of each corner, with the wider piece overlapping the narrower ones. If desired, additional pieces can be added along the bottoms and tops of all four sides, completing the board and batten look.

The last step is to rip a cedar fence picket, then cut pieces to lay on top of the planter, forming a frame. These pieces should have mitered corner, eliminating and visible end grain. Nail them to the tops of the legs, as well as into the tops of the four sides. Also nail diagonally across the miter joint, to hold it together and help prevent warping.

One Potential Modification

If part of the purpose for using garden troughs is to make it easier for elderly gardeners to work, without having to bend down, then the legs of the same planter design can be lengthened. Making the planter 30” tall makes it tabletop height or 36” tall makes it countertop height. In either case, it would be a good idea to add a course of the cedar around the legs, near the bottom, to help stabilize them.

wooden garden trough
Wooden garden trough, Chris La Tray

Making a Beam Garden Trough

While the garden trough made of cedar fence pickets is an inexpensive option, it’s not the strongest option out there. The cedar fence pickets will eventually rot, making it necessary to replace the planter.

The solution to that problem is to make a garden trough out of pressure-treated lumber. This can be done with 2”x 2”s, 2”x 4”s or landscaping timbers, depending on how massive a style is desired. Construction is extremely simple, using only one type of material for the garden trough and consisting mostly of stacking the piece and connecting them together at the corner. Garden troughs made in this way can be made much larger than the aforementioned ones out of cedar, as well as making them in unusual shapes, such as an “L” going around a corner. Due to the finished weight, such a trough should be built in place, where it is going to be used.

Since this is a garden trough, the first step is to create a leg or foot for the planter. Simply cut short sections of the material being used and set them in the corner. Then cut two pieces the length of the trough to act as a frame and set them on the feet, attaching them with nails or screw. Cut a series of pieces of the material to the dimension of the planter’s width and lay them across the two frame pieces, making them flush and attaching them. Remember to leave ¼” of space between these pieces for drainage.

From here, additional courses of material are added around the perimeter, up to the height desired for the top of the planter. The key to making it work, is to alternate the lengths of the pieces, so that the corner overlap each other, much like the courses of a brick wall overlap at the corners. Be sure to attach each new course at the corners, as well as every 8 to 12 inches down the sides. Stop when the desired height is reached.

Since this style is made of thicker material than the cedar trough, there is no need to place a top frame on it. However, adding such a frame, out of 2”x 6” or larger material, provides a place to sit while working in the garden or to lay gardening tools and supplies while using them.

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