About the SFMGA

Saturday, April 26, 2008

Hypertufa Planters

The look like stone, but you can make them yourself. Create custom shape and size containers for miniature landscapes or for special plants or placement or for a birdbath.

What you need

  • Plastic sheeting or heavy trash bags
  • Molds (start small with plastic bowls and tubs, foam coolers or boxes covered with plastic)
  • Disposable gloves and dust mask
  • Large mixing tub or pail and trowel
  • Measuring container (coffee can, etc.)
  • Sifted peat moss
  • Vermiculite or perlite
  • Fibermesh (fiberglass reinforcing fibers)
  • Cement coloring (optional, add ½ cup per 1 quart cement or experiment with it)
  • Portland cement
  • Wire brush
  • Dowels (½-1") or drill for drainage holes

What you do

Set up your mold or form upside down on a piece of plastic with enough overhang to cover it. The mold should allow your planter to be at least 5 or 6" deep. Cover mold with plastic to facilitate removal. (Or line the inside of the mold and form the planter in the inside shape.) Work in a place out of direct sunlight where it will not freeze and where the planter will not have to be moved for a few weeks. Large containers will be heavy, so you may wish to make them where thy will eventually be placed.

Put on your mask and gloves and mix on part perlite and one part peat in your tub with the trowel. Next add one part Portland cement and color if you wish. Proportions can vary. Combine well. Begin to add water slowly along with a handful of fibermesh. Stir well and thoroughly before adding more water. Mixture should be slightly damp and stick together when you squeeze it. Remove your mask when there are no more hazardous dusk particles in the air.

Beginning at the bottom, press small handfuls of the tufa mixture against the mold about 1" thick. If your mold is more than 12" in diameter, make the walls 2" thick. Too thick is better than too thin. Pat and tamp well to remove air bubbles and to bond tufa mix. Work your way up the mold and cover the top (which will be bottom when you turn it right side up) with 1" to 2" of the mixture, keeping what will be the bottom surface flat. To form the drainage hole now, use your finger or a dowel to poke holes.

When you have the shape and thickness you want, wrap the overhanging plastic around the tufa covered form. Mist it to keep it moist if necessary depending on weather conditions. After 2-7 days it will be firm enough to remove the mold, but it will be several weeks before it is fully cured. The longer you allow for the curing stage, the stronger it will be. Keep planter covered with plastic to slow drying until thoroughly cured.

When the planter is dry, use the wire brush to do any additional shaping or texturing. Any fiberglass that shows on the outside can be burned off with a blowtorch. Because concrete is highly alkaline, it is best to let the planter weather for a few more weeks outside so that the lime can be leached by soaking with a hose or from rain before planting. Cover drain holes with landscape fabric or plastic window screening before adding soil appropriate to your plants.

Your planter should last for many years outside.