Sally Scalera: Get crafty in the garden by making your own hypertufa containers

Today’s article is for all those crafty gardeners and I’m speaking literally, not figuratively.

If you’re creative, why not make your own containers to grow your plants in?  Make them for yourself, and also make them for family and friends since the holidays are here. The type of containers that I’m thinking of are hypertufa containers. Once you get the hang of it, they are easy and fun to make. 

Hypertufa containers are made from a porous, rock-like material that can be formed into a variety of shapes. You can even make hypertufa steppingstones, birdbaths or leaf castings. 

Hypertufa looks like rock and was originally made to look like an old English horse trough that was carved out of natural stone. The addition of peat moss and vermiculite or perlite to the cement mixture makes hypertufa creations lighter than pure cement.  Textures can vary, depending upon the recipe and the amount of water used.

The basic ingredients for hypertufa are water, dry Portland cement (not Quikrete), sand (this is optional, but it will give the container more strength and weight) peat moss and either vermiculite or perlite. 

You will also need rubber gloves, a face mask to use when mixing the dry ingredients, a container for mixing everything in (like a wheelbarrow for ambitious crafters or bowls for smaller projects), a mold for the container (examples include plastic tubs, liter drink bottles, foil pans, mixing bowls, Styrofoam coolers, cardboard boxes, milk cartons), trowel for mixing and a measuring container like a peanut butter jar, can or bucket.

Start with a basic recipe first:

1 part cement

1 part sand

1 part peat moss

1 part of vermiculite or perlite

When I made my hypertufa containers, I used vermiculite in the recipe. 

Depending upon the size of the container you plan on using as a mold, you will need a jar or can to measure the ingredients with. Measure ingredients by volume, not weight.

To begin, find a good workspace where you can be messy and possibly leave the finished container(s) for a day or two to cure. If you will need to move the container for curing, construct it on a board. Before mixing up the hypertufa, cover the mold with a plastic bag and place it upside down on a layer of newspaper.

Next, gather the supplies and then put on the face mask and rubber gloves. When mixing the ingredients, first mix the cement and sand together, then mix in the peat moss and then either the vermiculite or perlite. 

If you’re going to make a large container, divide the mixture into small batches to make it easier to blend the ingredients thoroughly. 

Make sure all the ingredients are thoroughly mixed before adding any water. Slowly mix in small amounts of water using only enough so that the mixture is easy to work with.  Aim for a consistency of cottage cheese and not crumbly (too dry) or runny (too wet). 

Check the mixture by grabbing a handful and squeezing.  The clump should hold together, and if any water is squeezed out, it should only be a few drops. If the clump crumbles, add just a little more water, mix it up and test it again. 

Repeat as needed, adding small amounts of water each time, until it is the correct consistency is reached. 

If the hypertufa mixture is runny, the rock texture will disappear, the container will be weak, and it could crumble once it dries.

When the hypertufa is ready, begin pressing the mixture on top of the mold and work down the sides. Try to get the sides thick so the container will be sturdy. 

If working on the outside of the mold, be sure to flatten the top of the hypertufa with a board (which will be the bottom of the completed container) so it will sit level.  Press the hypertufa to eliminate any air pockets. 

The last step, unless you’re going to grow rice, papyrus or any aquatic plant, is to create drainage holes in the bottom of the container. Otherwise, drainage holes can be drilled into the bottom after it has thoroughly dried.

When the new container is completed, cover it in plastic and let it sit for 24 hours. Large containers should sit for two days. 

After the container has set for at least a day, remove the plastic covering and don’t be surprised if it’s “sweaty.” Let the container sit for at least another week inside to cure and harden. Before planting anything in the container, set it outside to finish hardening and if it doesn’t rain, hose it down to leach out the lime. Rosemary plants, and other plants native to alkaline soils, would probably love the container without leaching out the lime, but most plants won’t grow well with a high pH.

Hypertufa recipes, with mortar mix and a cement bonding agent added, can also be used to make containers using towels that are dunked and coated in the hypertufa mixture and then draped over a mold.  Just search the internet for draped hypertufa pots to see what you could make for yourself or as gifts.

If you learn how to make hypertufa now, you will be prepared to make all sorts of creations, not just for the holidays, but for birthdays, too.

Sally Scalera is an urban horticulture agent and master gardener coordinator for the University of Florida’s Institute of Food and Agriculture Sciences.