By Marcia Kirinus, NC State Extension Master Gardener^SM volunteer

The doldrums of winter are now upon us, but there’s still plenty of work to be done to prepare your garden (either indoor or outdoor) for the more productive seasons ahead. For example, did you know with a bit of planning and some common materials, you can create your own plant containers from scratch? Known as hypertufa containers, these vessels can be a fun craft and a welcome addition to your container collection.

What is Hypertufa?

It is a lightweight, manmade, frost-resistant material that is molded to make outdoor planting vessels, garden art, and even outdoor pizza ovens given its high heat tolerance. Hypertufa ingredients are typically portland cement, peat moss, perlite, and water. However, you can substitute peat moss for a more renewable resource like coco fiber. You may also choose to use vermiculite instead of perlite –  note that perlite seems to add strength where vermiculite makes your mix more pliable.

Various hypertufa pots. (Left to right) Alpine plants in hypertufa at Oliver Nursery, Fairfield, Connecticut; hypertufa collection at Sarah P. Duke Gardens; evergreens in hypertufa at NCSU’s JC Raulston Arboretum. Image credits: Marcia Kirinus

Etymology of Hypertufa

Say it out loud – “HY-PER-TOOF-A.” Such a funny word. “Tufa” is a natural volcanic composite known worldwide.  In southern Italy entire towns are built out of tufa. Elegant homes, roads, and walls that date back to the Neolithic Age, all were built completely from tufa. “Hyper” would refer to, ’over the top’, so the word literally means, ‘over-the-top tufa.’

Civita di Bagnoregio, Italy, is an ancient Etruscan town hewn atop a hill of tufa. Image credit: Pixabay

What can I make from Hypertufa? 

A typical application for hypertufa is to make planting troughs that resemble old stone troughs from Europe, which can be an elegant and timeless addition to any outdoor garden. However, unlike heavy stone troughs or vessels, hypertufa is incredibly light, and you get to customize it and alter variables such as size, shape, depth, texture, and even color. Small spring bulbs do great in these types of vessels, planted over with lettuce, kale or arugula.

Materials List:

Mold

• Insulation board for mold – 4 sides and a bottom. Remember your pot will be built inside this mold so the final piece will be smaller than your mold.
• Roofing nails, 1 1/2”
• Blue painter’s or masking tape

Recipe

• 1 part Portland cement
• 2 parts peat moss
• 1 part perlite or vermiculite
• Handful of poly fibers (can buy this online)

Tools

• A bucket that you will use as a measuring vessel. I normally use a 5 gallon bucket , but the size you use will depend on the size of your final product. 
• Sieve to sift peat moss.  You don’t want large chunks or twigs. Hardware cloth works well. 
• Dust mask
• Waterproof or nitrile gloves
• Plastic sheet that you can use to cover your hypertufa for 30 days. A trash bag is fine.
• Wire brush or other shaping tools used to remove rough corners and texturize your final piece. This is done soon after you unfold. 
• Hose with shut off and watering wand
• Clothes that you can get dirty
• Wheelbarrow for mixing. If you don’t have a wheelbarrow, you could mix it in a large plastic tub.

The Setup:

• Do this outside or in a space you don’t mind getting dirty like a garage. You can put a drop cloth down if needed. This is a messy process.
• Don’t start this project at the end of the day. Set up will take a bit of time and you don’t want to rush. You should use the entire batch of hypertufa once you add water.
• You need a level working surface of comfortable working height

Making a Hypertufa Vessel:

Step one

• Choose a mold. A mold can be anything that is flexible or that breaks away. In the past I’ve used lamp shades, sink bowls, and plastic containers of various sizes and shapes. 
• If you want to make a trough, the easiest mold is one you make out of  1″ thick insulation board.  You can find this in the drywall/insulation section of your home improvement store. The styrofoam is easy to cut with a utility knife and it breaks away from your trough without trouble. 
• To hold the four walls together you will use nails and masking or blue tape.  Roofing nails work best as they have a big head and pointed narrow body that you can easily insert into the board.  You will first insert the nails, then wrap it tightly with masking/blue tape.

(Left to right) Sink vessel used as a mold. Resulting hypertufa planted with wood hyacinth, (Hyacinthoides hispanica). Old lampshade used as a mold, resulting hypertufa planted with night blooming Cereus, (Cereus sp.) Image credit: Marcia Kirinus

Step two

• Glove up (I double glove) and don a mask. Don’t breath in any dust – cement, perlite, vermiculite or peat which can be harmful to your lungs. 
• Run peat moss though a sieve to remove large pieces and twigs.  1/4″ hardware cloth works well.
• Mix all ingredients well until you do not see individual components of mix. The color should be uniform.
• Add a small handful of poly fiber. This is used to add strength to a pot. 
• Add water until consistency is firm and workable. Make sure mix is uniform. Keep material covered with plastic and use in small amounts.

Step three

• Start building your vessel from the bottom up. Pack the material in the mold, firmly pushing down to ensure there are no air pockets. Use the “pattycake” method, which is like making a hamburger (or a mud pie from your childhood). Build your floor first. Keep the bottom and walls uniform and about 1” thick. The part that is most visible is the rim of your vessel so do a fantastic job with that. 
• Don’t forget to make two to three holes at the bottom of your pot for drainage. I use a pencil for this. 

24 hours later

• Remove tape and nails from your mold. 
• Gently begin popping off the sides. The idea is to introduce air between the mold and hypertufa. Never pry the mold off. Once sides are off, assess if it is dry enough to slide the hypertufa on its base – introducing air to the bottom of the hypertufa so it does not cement itself to the base. You will know if it is dry enough if chunks or pieces do not fall off your tufa when you manipulate it. 
• Once the vessel is free of the mold, clean up the rim, scrape off extra pieces and sharp edges with a wire brush  or other tool. This can be done with anything like a butter knife, paint scraper, popsicle stick…. You can also use tools at this point to create a pattern on the surface of your tufa. Just be gentle. 
• Cover with plastic and don’t look at it again for 30 days. The best place to cure it is in a shed or garage. Avoid putting it on the ground or in a sunny hot spot. Wherever you put it, keep a plastic cover over it so it dries slowly. Rain is okay.

30 days later

• In 30 days your hypertufa is ready to be planted. It is rock solid but it will continue to cure and change color over time.

Planted trough with succulents becomes a complete garden. Image credit: Cornell Cooperative Extension of Erie County.

Additional Tips: 

• Never use only one hand to lift your pot.  It is very fragile until it cures. Always support all sides of your hypertufa and keep it flat. Do not bump it or move hastily with it. You might need help lifting. 
• When you are making your vessel, have extra molds on hand if you have left over material. You need to use up all of your material or waste it. 
• Anything can be a mold. Besides lamp shades and old sink vessels, I have used plastic shot glasses, small yogurt containers, and paper dixie cups to act as feet for my troughs. Be creative. 
• Thrift and discount stores have a variety of “molds.” I also purchased a wire trash can to use as a sieve. It was perfect. 

Additional Reading:

• Talking Tufa: North American Rock Garden Society: https://www.nargs.org/article/talking-tufa

• What the Heck is Hypertufa: Carrituck Cooperative Extention youtube video

• Hypertufa Planters: A Great Home for Native Plants: Master Gardener’s of San Bernadino County.

• Interesting ideas on texturing hypertufa styrofaom molds from the North American Rock Garden Society : Styrofoam Trough Innovations

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