What wood for flower boxes?

[Ron Kanter]

I need to build eight window flower boxes.
Roughly 45 x 7 x 8".
What wood would be the best type to stand up to the long term exposure to moisture that they will face?
Is exterior plywood with some kind of hardwood cap on the exposed ends worth considering?

[Tad Capar]

Pressure treated pine makes most sense to me. Home Depot sells 1x4 & 1x6. You would need to edge join them to get the needed width. Use gorilla glue. Make sure to provide drain hole for your boxes. If you want a better look and more challenge you can use a man made decking boards (trex, veranda, etc.)

[Matt Meiser]

Our old house had some that someone else made. They made wood frames from cedar sized to hold some plastic containers--wallpaper trays happened to be the right size for the windows. They held up nicely because they didn't see any more water than any other outdoor wood.

[Brian Penning]

Our old house had some that someone else made. They made wood frames from cedar sized to hold some plastic containers--wallpaper trays happened to be the right size for the windows. They held up nicely because they didn't see any more water than any other outdoor wood.

That's what I did years ago. The bottom is open except for a couple of narrow braces so the water simply drains out to the ground.
I just have a couple of metal brackets supporting mine.

[Rich Engelhardt]

They made wood frames from cedar sized to hold some plastic containers--wallpaper trays happened to be the right size for the windows.

Yep - just last week I picked up 30 cedar dog eared fence pieces from Menards to do exactly that.
They are 5/8" thick 5.5" wide and 6' long.
They were on sale for some rediculosly low price. Like $2.19 ea. or something.

Our local Sears Hardware and Appliance store is also closing and clearing out everything. They had a big pile of plastic trays a few weeks ago. I'm going to run over there this morning and see if they have any left.

If not, then I'll just tar the insides w/a mix of roofing tar and mineral spirits.

[Kent A Bathurst]

Just completed one - 10" h x 8" d x 8' l. Actually, the box is 10" w at the top of the front, and 8" wide at the bottom - so the front angles back into the house, rather than just a box w/ 90* angles everyshere.

The box itself is WRC, except that I used PT for the bottom.I also used PT for a french cleat on the house wall, and the front + sides extend 2" below the bottom to conceal the cleat.

PT is stronger than WRC, and better able to withstand the moisture over the long haul [hence - PT bottom], but I went with the WRC for the rest because it is more stable, "stain-able" now v. waiting for the PT to dry, and I like the appearance better than PT. Oil-based deck stain type of stuff.

I used stainless steel screws for assembly, with WCR plugs into counterbores. Where I fastened into end grain [like, through the front into the ends and dividers] I first put in hardwood dowels to give screws some long grain to bite into - and plugged the recessed dowels with exterior-grade wood filler on the inside of the box, to keep moisture away from the dowels - WRC plugs on the outside.

The "dividers" I mentioned - my thinking was that there would be a lot of outward force from moist soil, so I put dividers at the qtr-points on the inside - same general profile as the ends, but lower in height so they aren't visually distracting.

[Callan Campbell]

I've built a few flower boxes at that size or smaller. I always use Cedar since it's light, and with a large box that may need to come off a perch to be worked on, filled with soil, every bit helps! Using a plastic line or interior box to actually hold the soil will greatly prolong the boxes life. I always see much more loss of the Cedar board on the inside of the box while in direct contact with the soil than the exterior after 10 years or so. Besides, you can easily prolong the exterior of the wood with lots of different ways like paint, stain, etc. Not that easy for the interior except a liner or inner box. If there is any kind of covering like an awning over a window, that will also help to help some of Mother Nature away from your flower box. I'm about to design and build a new 8 footer for the front of my house, if I change wood species to heavier wood, I won't be able to raise or remove that size of a box by myself like I presently can with the Cedar, even filled with fresh soil and flowers. So, I'm thinking about that too.

[David Winer]

I need to build eight window flower boxes.
Roughly 45 x 7 x 8".
What wood would be the best type to stand up to the long term exposure to moisture that they will face?

I've made such boxes over the years, and my favorite wood species is cypress, stained brown. For appearance I like sides slanted 10 degrees (compound mitered corners). To preserve the interiors I put a heavy coat of roofing cement wherever soil is to be in contact.

[Jeff Todd]

if you plan to paint it or want it white. Azek seams like the right product. just put the woodgrain texture out if you want the wood look. it will hold up outside trouble free for a long time and is easy to work with.

JT

[Ron Kanter]

Thanks for all the great ideas.
Bonus points to Brian for including pics.
Kent, what are WRC and PT?
I try to stay way from any pressure treated wood if I have to do any cutting.
Cedar was/is my first thought, but I will definitely check out some of the composite materials.
Thanks again.

[Dave Lehnert]

What Rich said about cedar dog eared fence. Cheap and weather good. I use car under-body coating in a spray can to seal the inside of the box.

I would not spend a lot of money on wood for a flower box. Just good old untreated construction lumber will hold up well when painted. I built a set of Norms Adirondack chairs using just construction grade lumber. Keep a coat of paint on them and they lasted outdoors for 15 to 20 years. (1/2 time on a small covered patio, 1/2 sitting out in the open)

[Larry Edgerton]

I'll second Azek.

I have worked with it extensively if you decide to use it and have any questions. There are a few things you have to do differently from wood.

Larry

[Callan Campbell]

Thanks for all the great ideas.
Bonus points to Brian for including pics.
Kent, what are WRC and PT?
I try to stay way from any pressure treated wood if I have to do any cutting.
Cedar was/is my first thought, but I will definitely check out some of the composite materials.
Thanks again.

Western Red Cedar- Pressure treated Lumber- I'm guessing...

[Ron Kanter]

Sounds like a good guess to me.

[Kent A Bathurst]

Western Red Cedar- Pressure treated Lumber- I'm guessing...

Bingo......... Sorry - shorthand. I used PT only for the bottom due to concerns of longevity of the WRC over time, with constant moisture contact, and the extra strength of the PT v WRC. WRC may well have been fine - just took a notion. There should be fence-deck supply house[s] for the WRC - got a great one here in ATL - everything from dog-eared fence pickets through 12 x 12 - 24' timbers.

Re: cutting PT - In all honesty, I don't get all wrapped around the axle on this one. It ain't like being an electrician in Japanese nuke plants or anything. By the time the science is all said and done, it just ain't that big of a deal, especially compared to everything else in a WW shop. If I am going to cut a bunch, I just grab one of those disposable dust mask/filter things. Actually - dust intake was much worse with my ROS before I plumbed it to a vac. Also - emptying out the DC bin - Ye Gods!! - that's where the box of dusk masks lives - right by the cyclone.

Not at all advocating disegard of health issues, just saying.......EXCEPT - never burn that stuff - now you're sending up toxic plumes on the order of LA atmosphere. Just toss the scraps in the trash can.