Handmade Stone Containers
At the 1996 Dayton's Bachman's Flower show this spring, the area that
featured container plantings gathered lots of attention with the handmade
containers that looked like aged stone. These planters look like they
have been around for centuries, but are less expensive and lighter
weight. Articles have appeared in various books and magazines featuring
these containers and providing instructions. Here is a basic overview
of the process and some helpful tips:
Ingredients
- Portland Cement - not a cement mix with gravel
- Peat Moss - baled peat moss that has been milled
- Sand - use a fine grade such as mason's sand
- Substitute: perlite or vermiculite instead of sand
- Plastic - can be trash can liners or heavier grade
- Concrete Colorant - optional
- Fibermesh concrete reinforcement - optional
Supplies
- A bucket to measure ingredients, 1 or 2 gallons
- A large waterproof container to mix the ingredients
- Heavy rubber gloves
- A short piece of dowel rod, 1/2 inch or larger
- A chisel or strong putty knife and a wire brush
- A mold for forming the container
- A smaller mold for forming the inside - optional
Steps
- Measure and pre-mix all your dry ingredients.
- Line your mold with plastic to prevent sticking.
- Add water, slowly, mixing thoroughly.
- Mix until you get a cottage cheese consistency.
- Pack the mixture into the bottom a handful at a time.
- Use a piece of dowel to make two or three holes in the bottom.
- For larger containers, put in a smaller, inner mold.
- Start building up the sides by packing in small handfuls.
- Cover the filled mold tightly with plastic for 48 hours.
- Check to see if it is ready to unmold.
- The container is ready to unmold if you don't leave an imprint when you press on the mixture, but you can still scratch it.
- Gently unmold and remove all the plastic.
- Round off corners with a chisel or putty knife.
- "Weatherize" the outside with a wire brush.
- Brush off loose debris with an old paintbrush.
- Re-cover the container with plastic and let it cure for at least 2 weeks.
- Uncover and wash it out every two or three days to slow the drying process and to help leach out the lime from the cement.
Recipes
To make a small planter (dish pan size) it will take about 3 quarts
of cement, 3 quarts of sand and 6 quarts of peat moss. It is difficult
to say exactly how much of each ingredient is needed to make specific
size containers. Portland Cement is usually available in a 94 pound
bag (~$7), mason's sand 50 pounds (~$5) and peat moss in 2 cubic foot
bags (~$8). If you purchases those ingredients in those sizes, you
would be able to make at least 6 containers dishpan size or 2-3 containers
16 inches square. To make a container 12 inches tall, 2 feet long
and 18 inches wide, you would probably need a full bag of cement,
sand and 2 cubic feet of peat moss.
The texture of the handmade stone will depend on the proportions
(and choice) of the ingredients. Measure your ingredients by volume,
not weight. For a texture similar to natural stone, use 1:1:2, cement,
sand and peat moss. For a more nubbly texture, substitute perlite
or vermiculite for the sand. For a texture similar to sandstone,
use 2:3:3, cement, sand and peat moss. For a finer texture that
does a fair job at holding water, use 1:1:1, cement, fine sand and
peat and mix it drier than normal. To color the mixture, add 1 ounce
of concrete colorant per gallon of cement (not per gallon of mixture).
Tips for Success With Handmade Stone Containers
The sides and bottom of smaller containers (dishpan size) should
be around 1 1/2 inch thick. For larger containers, increase the
thickness accordingly.
Molds can either be built from wood or scavenged. Dishpans and vegetable bins from old refrigerators make great molds for small containers. For round containers, try using heavy nursery pots. Keep an eye out at garage sales and flea markets.
For a surface with more "ins-and-outs" (irregular surfaces), line your mold loosely with twisted or bunched up plastic. Leave the bottom smooth.
Never pick up an uncured container by the sides.
The slower it cures, the stronger the container. Several weeks curing and rinsing is a minimum.
A slurry of cement and water can be smoothed over the surface for a more finished look.
To strengthen the mixture for larger containers, add a large handful of Fibermesh to each gallon of dry mixture. When you brush off the outside of the container after you take it out of the mold, these fibers will make it look fuzzy. Don't worry about them at this stage. After it has cured for a few weeks, the fuzz can be burned off. To do this, you quickly pass a torch across the fibers, being careful not to hesitate and heat the handmade stone (it will cause small potholes).
It is important that the containers be aged and weathered to allow excess cement
to wash away.
Wintering Your Containers
If at all possible, store the container empty, dry and indoors.
Second best, you can move them into the garage after a killing frost.
This will allow them several weeks to dry out thoroughly before
freezing temperatures. Soil could be left in the containers if it
has sufficient time to dry out. A moist soil mass could easily crack
the pot as it freezes and expands. If left outdoors, or if there
is still a lot of moisture in the pot when it freezes solid, the
moisture will expand and cause flaking and possibly cracking.
© Bachman's 1996
Author: Margaret Purcell, Senior Horticulturist
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