Two Takes on Styrofoam Trough Making

Kendall McLean and Dale Greer

This project features two separate articles by members of NWNARGS on how to make planting troughs from Styrofoam containers. The first originally appeared in the NWNARGS Newsletter in 2018, the second was written especially for this Web site. Enjoy!

Making a Styrofoam Trough

by Kendall McLean

The advantages of styrofoam troughs are many.  First and foremost, they are much lighter than stone, concrete or hypertufa.  They have insulating qualities that are helpful for plants exposed to cold weather.  And it is easy to make them unique in color.  My troughs have lasted for years, and they even grow moss in my damp and shady yard.

All Styrofoam troughs start out the same way – find a fish box or other styrofoam shipping box.  From there, you can go several different ways. 

 

 

I start by cutting down the top edges of the box to create a rougher and uneven top.  This also determines the depth of the trough. Then I shape and roughen the box with a wire brush to make it look more like rock or concrete. I particularly try to round off square corners.  There’s a lot of floating bits of Styrofoam from this process, so you may want to do it outdoors.  People also use heat to make the surface uneven. A hairdryer or heat gun can be used.  Styrofoam will melt, and just a little melting looks good but too much can be a disaster.  You can also use a knife for scoring the Styrofoam.

Once I have the shape and texture I want, I cut some holes in the bottom with the same sharp serrated knife I used on the sides.  You can use a drill if you prefer round drainage holes.  I lay some fine screening over the holes to keep the planting medium from dribbling out the bottom, and tape it down.  Scotch tape is enough – the soil will hold the screen down once you plant the trough.

At this point I take the trough inside where I have set up a painting area.  If you have a covered area outdoors or it’s warm and dry weather, okay. 

Several types of paint can be used.  Places like Habitat for Humanity have cheap quarts of exterior latex paint, often in browns or greys, which applies well and lasts outdoors.  Also artists’ acrylic paints work well, and there are some cheaper brands which are not prohibitive for this work.  They allow a wider range of colors.  I have had trouble in the past trying to paint styrofoam with spray paint, so use caution if you want to try that. 

The best looking troughs I have seen have multiple colors, usually subtle ranges of grey, green, brown, etc.  I also like a sort of terra cotta color.  Black can also be effective. But of course you can paint them bright blue if you want to. Mixing sand into the paint or sprinkling sand on while the paint is wet can give a rougher texture.

Once the paint dries, you're ready to plant!

Repurposing Styrofoam Shipping Containers into Attractive Lightweight Garden Planters  

by Dale Greer

If you have ever received merchandise (plants, bulbs, Omaha Steaks) in Styrofoam shipping containers and then didn't quite know what to do with the empty container, but were hesitant to send it off to the trash, here is a quick and easy way to convert it into an attractive lightweight garden trough/planter.

 

The following 'recipe' is courtesy of Sandy and Ted Milam, after which I will add my take including photos of the process and finished troughs (or StyroTroffs as I like to call them).

 

Traditional Hypertufa troughs are made of cement. They're heavy! Here is a recipe for a lightweight version that you can make and enhance for natural effects. They can last for several years.

 

Materials:

 

  • An empty, polystyrene box, such as a fish box, from a fish market or supermarket

  • A wire brush or other tool to rough up the outside of the box

  • Optional: heat gun to slightly melt and round corners and make shapes

  • One or two colors of tough porch or deck paint - rock colors

  • Some sand, grit, pumice, gravel or mortar mix for texture

 

Process:  Scrape and scar the box surface, round sharp corners and mimic rock surfaces. Paint on one color as an undercoat, then add the second color to give a mottled effect and enhance texture. Or add a light coat of mortar mix for more of a stone appearance.

 

Remember to carefully punch drainage holes in the bottom. Plant with small and slow-growing plants. Stand the trough on a pair of bricks and dress with gravel.

I started with this recipe then adapted it to create my own process and finished planter...

 

Acquiring a variety of sizes of styro shipping boxes isn't difficult. Thicker-walled boxes work better and provide better sturdiness and root insulation for the plants that come later.

If the box has a lip that seats the lid down, I cut this off with a fine hacksaw blade. It's easiest to use just a blade to do this without the interference of the holder while cutting... 

Drill or cut drainage holes in the bottom of the box, as many as you think are needed. I use a circular saw drill bit on my cordless drill & punch through from both sides to minimize tear out on either side.

Start roughing up the outer surface with a coarse wire brush, rounding over the edges and any exterior unwanted surface forms. You will want to have a Shop-Vac handy to vacuum the bits of styro that come off with the wire brushing and cling to everything: hands, clothes, floor, trough…

Cut and staple wire or plastic window screening over the drain holes to keep soil inside and on the outside bottom to keep out sowbugs and slugs (which always seem to find their way into such places).

 

Once the outside surface is to your liking, it's time to paint! I went to Daly's paint store in Fremont and picked up several colors of returned paints (for cheap) in natural stone colors that produce an "eggshell" finish, selected colors that would go together on a trough, then started painting on the 'undercoat color'. Once that is dried I stippled on top of that color the chosen complimentary color by dipping the brush into the paint, lightly removing excess paint from the brush on the can edge, then tapping the brush on the trough giving it a speckled effect. On another trough you can reverse the colors.

If you want additional effects like fissures with crystal pockets, you can paint a darker 'crack line' and then glue small quartzite or other contrast-y stone chips onto this 'pocket'. I also added bronze filings (I have done bronze casting and saved the filings) to add the effect of 'pyrites'.

Once the paint and other exterior finishes have dried it is time to have fun with planting your new and fabulous StyroTroff! I place a bit of broken crockery over the screen on the drain hole so the screen doesn't clog with soil mix over time. Then add your preferred soil mix and artfully place and plant your chosen plants along with special rocks and gravel mulches.

 

And voila - You have a new and wonderful container garden, created from start to finish...

 

Have fun!

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