How to Build Garden Arbors

And How to Keep the Project Cheap

Garden and path arbor, colors of summer
Darrell Gulin/Photographer's Choice/Getty Images

Building small garden arbors is an easy do-it-yourself project -- cheap, too, if you're willing to shop around a bit for your pressure-treated lumber. The design in this project calls for a two-post structure, but you can apply the same principles to a larger structure (a four-post unit, such as the one shown in the picture here, will be more likely to remain plumb as the years pass).

It will take the average do-it-yourself landscaper two days to build this garden arbor.

Design Basics: An Overview

Think of this project as involving five architectural layers:

  1. Concrete placed underground will secure the structure.
  2. Two 4x4 posts will be sunk into that concrete.
  3. Two 1x6 crosspieces will run along the sides of these posts at the very top, perpendicular to them. One crosspiece will be on the outer side, the other on the inner side; thus they will "sandwich" the top 6 inches of the upright posts.
  4. 2x4 rafters, in turn, will lie atop the crosspieces, perpendicular to them.
  5. And 2x2s will lie across the rafters, perpendicular to them.

Cost of the Garden Arbor: Shopping Around for Cheap Lumber

The cost of lumber for this project depends to some degree on the do-it-yourselfer's willingness to shop around. We went to a discount store to purchase the pressure-treated lumber for our own project. Now, to be sure, a lot of rejects end up in the lumber bins of such a store. We had to sort through about 20 boards on average to find one good board.

Is it worth the extra work? Well, judge for yourself as you look over the following list of surprisingly cheap prices (measurements are in feet; currency is in 2004 U.S. dollars):

  • Five 2x2x8s at $1.50 each
  • Three 2x4x8s at $2.48 each
  • Two 1x6x12s at $3.88 each

Even after the price for the two 4x4s is added in, the total for lumber came only to about $30.

If your information about building arbors derives from television shows, it may be hard for you to believe at first that the wood for a small arbor can be purchased for around $30.

Lumber Supplies (Pressure-Treated):

  1. Five 2x2x8s
  2. Five 2x4x3s
  3. Two 1x6x12s (hereafter referred to simply as the "crosspieces")
  4. Two 4x4 posts

Other Supplies:

  1. Gravel or crushed stone
  2. Pre-mixed concrete
  3. Deck screws
  4. Bolts, washers and nuts
  5. Scrap wood
  6. Safety supplies: goggles, face mask, and gloves (you will be wearing these throughout the project to help avoid injury)

When lumber dimensions are given here, a convention is being followed; that is, note that a 4x4 is not really 4 inches by 4 inches. It sounds odd, to be sure. But everyone calls them 4x4s, so the present article is following that convention. In fact, they measure 3.5 inches x 3.5 inches. Likewise, the so-called 2x4s are really 1.5 inches x 3.5 inches.

Fully dried lumber warps less than lumber that still retains significant moisture. If your vertical 4x4 posts fall into the latter category, your garden arbor may become crooked over the years, especially if it's just a two-poster.

Tools to Build the Garden Arbor:

  1. Wheelbarrow
  2. Garden hose
  3. Shovel
  4. Carpenter's level
  5. Jigsaw
  6. Circular saw or handsaw
  7. Drill
  8. Wood chisel
  9. Spade bit
  10. Stepladder
  11. File
  12. Tape measure
  13. Hammer
  14. Wrench

Let's Get Building!

Once you've gathered your supplies, you are now ready to start building the garden arbor, beginning with some concrete work to ensure the sturdiness of your arbor design. That is, we must begin with the foundation for the garden arbor. This requires digging post holes, plumbing the arbor's posts, and pouring the concrete that will hold them in place.

  • Dig two holes, spaced as far apart as you want the main posts of your wooden arbor to stand (in the completed project described here, the posts stand about 8 feet apart on center). Make the holes about 1 foot wide and 3 feet deep.
  • Place about 1/2 foot of gravel or crushed stone into the holes for drainage.
  • Set one 4x4 arbor post in one hole, the other in the other hole.
  • Lay a board across the tops of the two arbor posts. Place a carpenter's level on the board. If the board is level, your posts are standing at equal heights -- which is what you want. Otherwise, make the necessary adjustment.
  • To ensure that the posts will be plumb (i.e., the vertical equivalent to "level"), nail scrap lumber to each of them to form temporary, stabilizing braces. With these braces in place, check for plumbness on all sides with a carpenter's level. If the posts aren't exactly plumb, adjust the positioning of the temporary braces, accordingly.

Lumber-Buying Tip

Be careful, when buying your 4x4 posts, to get the height you'll need. Remember, an 8-foot post sunk 3 feet into the ground leaves you with an arbor only 5 feet tall. If you get a deal that you can't pass up on some 8-foot 4x4 pressure-treated posts, though, it is possible to compensate for their lack of height. Buy galvanized post anchors for each post. Sink the post anchors into the concrete, instead of the posts themselves. The pressure-treated posts would then be attached to these anchors, meaning all 8 feet would be above ground. Post anchors, however, can be expensive, so make sure that you're not defeating the purpose of getting the lumber at a cheap price!

Securing the Posts With Concrete

Update: Some experts now advise against the concrete footings, warning they hasten the demise of the lumber. They suggest using pea gravel underneath and around the posts. "Soil will seep between the gravel pieces and the sand/clay mixture that invariably comes in the bags of pea gravel," says contributor, Lynn Stevens. She continues, "Well tamped, the combination will be strong but also allow drainage."

If you still wish to pour footings in the traditional fashion, the instructions are as follows:

  • Dump a bag of pre-mixed concrete into a wheelbarrow. Add water from a garden hose. Stir the water into the concrete with a shovel, until achieving the right consistency.
  • Pour this concrete into one of the holes, around the base of the post. Repeat until hole is filled; and repeat for other hole.
  • Allow this concrete to dry, or "cure" for at least one day.

While waiting, lay out the other boards on the ground, make your measurements, and pre-cut and pre-drill as much as possible, to save time.

With the concrete work done, the focus shifts to carpentry. Since these instructions are meant for non-carpenters, the emphasis will be on the easiest way to accomplish each task.

  • An Optional Design for Added Flair: Cutting a design into the ends of your crosspieces is simple with a jigsaw. First trace out the design on the lumber with a pencil. Getting a rounded edge can be as simple for beginners as tracing around a saucer.
  • Once you have one end-design cut out, use it as a template for the other three.
  • Next Architectural Layer -- the Rafters: Five rafters will sit atop the crosspieces, and they'll be 4 feet long. So cut up your 2x4s now with a handsaw or circular saw to make these rafters.

Notching the Rafters

  • Now we'll notch the rafters, for a tighter fit atop the crosspieces. Note also that, by adjusting the depth of the individual notches, you can correct discrepancies in levelness. This can be important when working with discount lumber. For instance, if one of the crosspieces is "bowed" (higher in the center than on the ends), your only chance to make the proper adjustments may well lie in your notching.
  • Lay each rafter down on the ground the long way, so that one of the 2-inch dimensions is on the ground, the other facing up. On the part facing up, find the center point lengthwise. From this center point, measure out 1 3/4 inches to the left (mark with pencil) and 1 3/4 inches to the right (mark with pencil).
  • Now simply repeat the last step, except you'll be going over another 1" on both the left and the right.
  • It is from these two 1-inch areas, on either side of the 3.5-inch center area, that the notches will be cut. The notches will fit over the two 1-inch-wide crosspieces.
  • On each side of the 4-inch dimension, measure down 1 inch. Make several 1-inch cuts down into this notch area, using whatever saw you're most comfortable with.
  • Now go back with a hammer and wood chisel and strike into these cuts; chips of wood will start coming out, and you'll have a notch in no time. After chiseling, take a wood file and file away some of the roughness on the chiseled surface. Repeat for each (you'll have ten notches in all).
  • Now that the cuts have been made, the focus switches to attaching the boards together to assemble the garden arbor.

The first step in assembling the garden arbor is to line up the crosspieces and the 4x4 posts. Once lined up properly, you'll be boring a hole that will stretch through all three pieces of wood, allowing you to insert a bolt that will unite the three pieces. You'll begin at one post, and then repeat the process on the other post.

Assembling the Garden Arbor

  • If you're not confident enough with your measuring skills to pre-bore all the holes and then fit everything together after, then it's time to bring the crosspieces over to the 4x4 posts, so that they can be lined up properly.
  • First measure down 6 inches from the top of each post, on either the outer or inner side (doesn't matter which), and mark it with a pencil. For each post, take a small piece of scrap lumber, and screw it into the post with a couple of screws, so that the top of the scrap lumber runs along the line you just drew. Pick scrap lumber that is long enough so that it will protrude a couple of inches or so beyond each side of the post. These little "shelves" will function as temporary supports for your crosspieces.
  • Now take one of the crosspieces and lay it across one of the temporary shelves (either front or back). The crosspiece should now be positioned in just the way that it will eventually lie, when the project is done.
  • With this crosspiece lined up properly with respect to the posts, attach each end with a couple of screws, one near the top, one near the bottom. Repeat with the other crosspiece. Now you can remove the two temporary shelves that the crosspieces are resting on.

You're now ready to make your wooden garden arbor design come to life. The next step in the building process is to tie your crosspieces and posts together.

  • Insert a spade borer into a drill. The width of the borer will have to match the width of the bolts that you've chosen. We chose 1/4-inch bolts, so we used a 1/4-inch spade borer.
  • With posts and crosspieces lined up, you can now use the drill with its attached spade borer to drill a hole through the crosspieces and posts (both left post and right).
  • When boring the holes, keep the drill as level and as straight as possible. You don't want to end up with the front hole an inch higher than the back hole, say.
  • If the borer doesn't penetrate all the way through, there's an easy way to avoid having to drill first from one side, then from the other, hoping the two holes will meet. That's a bit too dicey. Instead, take the easy way out! Bore through as far as you can (you should be able to get half way into the post, anyhow), then remove the crosspiece that you've drilled through. Now continue boring through the post. You should be able at least to pierce the other crosspiece. Then you can widen the entry by switching sides and boring through the other crosspiece.
  • Now hammer the bolts through the holes, and apply the washers and nuts.
  • Take the rafters that you've already notched, and just slip them over the crosspieces, perpendicular to them. The notches will tell you where they fit, if you've measured properly in your notching; so this step is easy.
  • Attach the rafters to the crosspieces with deck screws.
  • Finally, lay the 2x2s on top of the rafters, perpendicular to them. Attach with screws.
  • And you're done. Wait at least 6 months before staining your pressure-treated wood.

Because of the wait involved before you can stain the wood of your garden arbor, you won't be able to plant any vines on it for that first summer. Instead, spend the time looking at other people's arbors, and see what plant choices catch your eye.

The History of Arbor Day

Supports for climbing roses and wisteria are two widespread aesthetic uses for arbors. Meanwhile, trellising grapes on arbors is a traditional horticultural use for them. But at this point in the discussion, we have moved beyond the building of arbors to a treatment of their function (for more on that topic, see below).

You've probably heard of "National Arbor Day," and perhaps you've wondered what that holiday has to do with the garden. Arbor Day history goes back to the 19th century. It begins with a man named J. Sterling Morton and is a holiday on which trees are honored. People plant trees on this day to celebrate the importance of trees to human life. Arbor Day history is thus part of the modern movement towards awareness that we may need to cultivate "nature" a bit in order to preserve it.

What of the linguistic origin behind National Arbor Day? Well, arbor is the Latin word for "tree." But the word that denotes the trellising structures we've been discussing, such as grape arbors, has a different origin. It derives from the Old French erbier, meaning "garden." Is there a connection between grape arbors and trees? Well, "arbor" first and foremost signifies a leafy, shady recess formed by tree branches, shrubs, etc. Only secondarily is it defined as "a latticework bower intertwined with climbing vines and flowers." Clearly, then, there is a connection: Our grape arbors (i.e., "latticework bowers") have been developed out of a need to find stand-ins for shade-giving trees in our gardens. The coincidental similarity in spelling between the Latin word and the French word led writers of English to exploit the connection and use "arbor" as the spelling for the trellising structures that grace our gardens.

Despite this connection between National Arbor Day and their trellising namesakes, National Arbor Day is purely a tree holiday. If you want to celebrate Arbor Day history and do your part, then plant a tree; save your plans for building a grape arbor for another day.

The official Arbor Day Web site relates Arbor Day history in greater detail. According to this site, it was on January 4, 1872 that J. Sterling Morton first proposed a tree-planting holiday. The proposal was made in Nebraska, which at the time was more or less a tree-less state. Morton's proposal was adopted, and the idea of observing such a holiday spread to other states later in the 1870s. States today most commonly observe National Arbor Day on the last Friday in April. The observance of National Arbor Day has even spread beyond the borders of the U.S.

Uses for Arbors: Supports for Grapevines, Privacy Screens, and More

The trellising structures we've been discussing have many uses. For instance, there are the classic grape arbors, in which case the structure has a horticultural function -- serving as a trellis for a crop. Specifically grape arbors come to mind for this use due to their historical prevalence.

But such structures -- in conjunction with the vines that grow on them -- can also serve as privacy screens. Another function is to provide shade, including on decks and patios. More often, they have primarily an aesthetic purpose. Some landscapers like the look of a wooden archway that forms an entrance to a garden. Indeed, the arched arbor is perhaps the most popular style, currently. For instance, they can function as entry gates for properties surrounded by fencing.

Trellises and Pergolas

Two related structures are the " pergola" and the simple trellis. Any structure designed specifically to support vines is often called a trellis now, although the trellis traditionally was a latticework structure. Trellises can be very simple, nearly two-dimensional structures and are often either driven into the ground (freestanding) or laid against a house or outbuilding.

"Pergola" is more difficult to define. In some circles, it may be just a fancy way of saying, "arbor." Oversimplifying for the sake of brevity, it may help to focus on the fact that the word, pergola is Italian. Renaissance Italy loved its pergolas, which were essentially grape arbors with masonry columns, rather than wooden posts.

But this distinction, based on whether the supports are wooden or masonry, is breaking down now, as people use the term "pergola" more loosely. If there's any distinction at all that is still maintained, perhaps it is that pergolas are structures of somewhat more substantial architecture. Others claim that the roof of an "arbor" is arched, while that of a pergola is flat.

Be that as it may, let's say this much: If you're invited to a party at a house with a pergola, you're more likely to be served sherry than plain old wine, as you engage in a genteel chat about Arbor Day history.