Making hypertufa pots for your garden is a great way to gear up for summer planting.
Hyper tufa is a “rock” made from peat moss and perlite bonded together using Portland cement. It was originally created as a substitute for tufa. Tufa is a rock composed of calcium carbonate that has been exposed to long periods of water. Tufa pots were used predominately in Alpine gardening so the hpertufa is good substitute as it is very porous and can sustain temperatures as low as −22 °F /−30 °C. They look great with succulents, cacti and annual plantings. I like to mix mine together in the summer. I replant in the winter and bring them indoors. You can leave them outside all winter, but I do suggest turning them upside down.
Hypertufa is easy to make, pots and planters can be made in any shape and they are very durable. The first ones I made 4 years ago are going strong. They are lovely amongst flower beds or on their own and make a nice alternative for container gardening.
Here is the recipe and equipment I use:
Food Spray Oil
Screen for peat moss
Stiff wire brush
The proportions for the mix by volume:
1 part Portland cement
1.5 parts sifted peat
1.5 parts perlite/vermiculite
Measure the peat moss, perlite and the Portland cement, into a wheel barrow or other large container.
Using gloved hands and wearing a dust mask mix the dry ingredients.
Add water slowly, mixing with your gloved hands until the material is the desired consistency. The total amount of water needed will depend on the dryness of the peat moss and the humidity in the air. The mixture shouldn't be runny -- too much water and you'll get a weak container. A free-form container needs a drier mixture so that it will hold its shape.
To test for the right consistency, squeeze a handful of mix. You should be able to get only a couple of drops out and it should be about the consistency of cottage cheese.
Spray molds with oil if concerned about the mold not coming off.
Push mixture into molds and smooth off the edges.
The pots need to cure. Curing refers to the drying of the material and to the chemical bonding that takes place. Curing has two stages: an early stage when the planter should not be moved, and a longer drying period following removal of the mold. The initial curing period takes 14 to 36 hours, while the latter takes about three weeks.
For the first 36 hours, cover your planter with plastic. The plastic slows the curing down and converts the alkali for stronger bonding.
After a day and a half, test the hardness of the mixture with your fingernail. If you can scratch the surface, the mixture is still too soft and should be left for a few more hours and then retested. When it requires a screwdriver to scratch the surface, the planter is ready for the second stage of curing.
Carefully remove the mold from the planter, and then smooth the corners and rough edges with a stiff wire brush if you need to. You can texturize the planter by scoring it with the brush. Be careful not to press too hard, as the walls are still friable. Leave the planter in a shady spot for 2 -3 three weeks to finish curing.
After curing, the planter will be a lighter color and will weigh less. The last step is to leach out any strong alkali or free lime contained in the Portland cement.. Leach away the lime by filling the porous planter with water. Over the next ten days, refill the planter whenever it's empty.
The planters are naturally porous, but if you want additional drainage, drill a hole in the bottom using a masonry bit.
If you want to add moss to your hypertufa pots, find moss that is growing on rocks and stones.
Place the moss on the pot and spray with water or a very dilute vinegar solution.
You can also make a moss paint using
1 c buttermilk/beer/yogurt
1 tsp sugar
moss from rocks or stones
Blend all the ingredients and paint over the pots. Keep in the shade and spritz with water occasionally.
Blog contributed by Fiona Davis, Ceramics Director at ArtisTree.