: I looked at ladder trellises at my garden store, but they are too expensive. The design does not look complicated. If I try to copy and build one myself, what is the proper procedure to make one? — Martha G.
A: Building a ladder-style trellis is a great project for beginning do-it-yourselfers. The design is relatively straightforward and, being a triangular configuration, it is extremely strong. If you don’t get the nails secured properly, it will still be adequately strong to support the plants.
The name “ladder” trellis pretty much describes its basic design. It consists of two ladders, which are connected together at the top forming an “A.” Make it just slightly taller than your height. This allows you to get underneath it without too much bending and allows you to reach the plants for pruning.
You might also consider making one or two of them, which you can walk under. If you do this with a standard “A” design, it will have to be quite tall. Instead, connect a third horizontal ladder across the top of the two side ones to provide more free width. This does weaken the trellis somewhat, but it will still be strong enough.
It sounds as though your budget is somewhat tight, so pressure-treated lumber is an obvious material to use. It will hold up well outdoors, particularly in a damp garden area, which is often watered. Its downside is it will not accept paint well and it is not a naturally attractive wood.
If the climbing plants you plan to use have dense foliage, it may nearly cover and hide all the wood.
Two other, more attractive, but also more expensive, material options are cedar and redwood. Cedar will weather to an attractive natural gray color or it can be stained. It resists rotting fairly well, but not as well as pressure-treated lumber or redwood.
Redwood is the most expensive of the three materials, but you still may be able to make it fit your budget. With its excellent rot and insect resistance, its lifetime cost may be less than cedar. You will have to apply only a clear or lightly tinted sealer to the redwood to maintain its beauty.
To lower the overall cost of the redwood, use the most expensive construction heart grade for only the posts, which contact the ground. For the remainder of the trellis, use construction common grade, which is less expensive. It will have some knots and perhaps a slightly lighter color, but it still is attractive.
To make construction simple, build the ladders in your garage and then connect them in your garden. Building them on a smooth, flat floor makes it easier to keep them square. Space the rungs about 1 foot apart unless the plants will have sturdy vines. In that case, place them further apart and save lumber.
If you can afford it, use stainless steel fasteners instead of galvanized ones. Once you assemble it outdoors, dig postholes. A depth of 2 feet should be adequate. Place several inches of gravel in the bottom first, set the trellis in place and fill the rest of hole with more gravel.