The DIY Garden Arch; Easy, Organic and (almost) Free

The twig and branch arch that divides the main upper garden from the white/herb garden near the house looks almost as though it grew there naturally, and every time there’s a garden tour it gets more comment from visitors than most of the plants. For years I have been promising to explain how Bill builds them, so here finally is the how-to.

our new arch, right after completion

You will notice I called the arch “them” even though there is only one. That’s because structures like these biodegrade pretty quickly. The corner posts are durable – ours have been in place for 15 years and show no signs of declining – but the lacy branch work that makes the arch lasts only about 5 years, at least here in the Northeast where it’s exposed to pretty fierce weather.

This is a good thing. Whether you let it go as long as possible or decide to take it down earlier, everything will return to the earth without leaving paint residues, major quantities of rusting metal or other unpleasantness. There is no debris to dispose of except a little bit of wire and a few screws.

When I had Bill proofread these instructions to be sure I hadn’t missed anything, he said “This sounds complicated! If I had to read all this I’d never build anything.” It sounds more complicated than it is, but if you are as handy as Bill ( and as disinclined to read directions before plunging into projects), all you have to do is scroll through the pictures and you will know all you need to.

For those who would prefer a bit more guidance, I’ve written it up like a recipe. But please think of it as a recipe for stew, not a recipe for cake; it’s just a way to get you started. Bill can build an arch from posts to completion in an afternoon. You might want to spread it out, scouting for saplings and setting the posts on day one, building the arch on day two. Just don’t cut the saplings until you’re ready to use them; they stiffen up quickly and you want them to be as flexible as possible.

Materials (For an arch 6 feet wide, 20 inches deep and 9 or 10 feet tall) :

4 4-inch diameter 8-foot length cedar or locust posts, available at lumber yards

4 12-14 foot willow, oak or maple saplings, roughly 1.5 inches in diameter at the base. The ones that grow deep in the woods are more likely to be tall and straight because they’re reaching for the light. Make sure the main trunk is flexible from about 5 feet on up; sometimes skinny trees are older and stiffer than they look.

2 straight(ish) branches roughly 6.5 feet long and a generous inch in diameter .

12 to 15 straight(ish) branch pieces, each about ¾ inch in diameter and 19 inches long. This sounds like a lot, but most if not all of them can be gleaned from sapling branches you will be removing. It’s ok if 5 of them are only about ½ inch thick.

An assortment of different length screws: 1 to 2.5 inches long ( You won’t know exactly what sizes you need until you have the saplings and branches).

A roll of the thickest wire you can easily use as though it were string: 14 to 16 gauge probably.

Tools:

Shovel and trowel ( a post hole digger is better, should you happen to have one lying around. These instructions assume you don’t)

a pruning saw

Pair of pruners

Cordless drill

Wire cutter ( some pruners have one built in)

A ladder

Method:

1. Set the posts in pairs, 18 inches from center to center, the pairs 6 feet apart on centers. Bases should be buried 14 to 16 inches deep. If the soil is loose you can dig narrow holes using nothing but the trowel. If it isn’t, you’ll have to go at least partway down with the shovel, then backfill.

2. Cut the saplings. If you can’t get the 6 foot pieces from their side branches, cut lower branches from other trees. ( they don’t have to be the same kind of tree).

3. Bring the harvest to a spot where there is plenty of room to work, i.e. the lawn. Remove all branches from the bottom 6 feet of the saplings, so you have very skinny poles with very branchy tops. Bill just leaves the leaves in place; they fall off after a few weeks. You can remove them if you are a neat freak but then I take it back about one afternoon.

4. Prune side branches and twigs from the prunings to get the short pieces.

5. You are now going to tie the posts together with short pieces and build a ladder across the top of the arch to stabilize it. Use the hunkiest short pieces near the bottoms of the posts, the thinnest ones across the top. Let everything overlap a little. (Screws should be at least ¾ inch in from the ends or they’re likely to split the wood. And you need overlap to make tying things together easy.)

Bill trying out a cross piece

Okay. Attach the short pieces to the posts at regular intervals, screwing them to the inside faces. Attach the 6 foot pieces to the insides of the posts, around 2 inches down from the tops. Get up on the ladder and lash the cross-pieces to the tops of the 6-footers. ( You would think this would be easier to do on the ground, but everything is so irregular it doesn’t work out that way.)

6. Set the sapling bases against the outsides of the posts, starting about a foot off the ground, butting them up to the cross-pieces. Screw them into place.

7. Now comes the interesting part. Get up on the ladder and bend the saplings down to form the arch. They can go in parallel or be crossed kitty-corner, whichever is easiest and most attractive. Tie them to the tops of the posts, weaving the wire in and out around the cross piece ends to keep everything secure.

8. The arch is still having a bad hair day. Weave the branches in and out around each other until the shape is under control.

There; that’s it. Plant some vines. Clematis, perennial sweet peas and annuals like cup and saucer vine and Spanish flag work well, or you can plant climbing roses and pray they make their own woody frame before the arch gives out.

The previous arch, covered with Clematis virginiana and doing fine until this year’s Patriots Day Storm.