Concrete or stone planters are always favorites, but their weight can be a problem!
Hypertufa pots and planters are an attractive alternative to materials such as concrete and stone. Hypertufa is a man-made substitute for Tufa rock. Tufa is a spongy cellular rock found in limestone country and especially where water has worn and leached out original materials to create a porous spongy consistency. In many countries throughout the world this natural stone has for centuries been hollowed out and carved for pots and garden planters. When properly surface-treated it has the appearance of natural aging and ruggedness.
Hypertufa is made from a mixture of Portland cement, sand and peat moss, and can be fashioned into stepping stones, birdbaths, in addition to just about any size or shape planter. Perlite can be substituted for the sand and will lighten the weight of the planter.
Hypertufa instantly looks aged, attracts lichens and mosses and has a natural look to compliment plants and shrubs in the garden. Hypertufa pots are very plant friendlythe bulky and porous wall thickness acts as a reservoir for water from which the plants can drink between showers and waterings. Being porous, it also allows for easy passage of air to the root system.
Hypertufa pots are suitable for many types of plants and are particularly good for cacti, sedum, succulents and alpine plants.
Below, Leo of Rose-Hill Gardens in Wisconsin demonstrates how to create custom hypertufa bowls, pots and planters. These hand-made planters are a unique, rustic way to feature any of the 100+ miniature perennials that Rose-Hill Gardens carries.
How to make a Hypertufa Planter:
- For a square or oblong tub you will need two cartons or coated cardboard boxes, one of them with smaller overall dimensions by at least 5 or 6 cm. Place the smaller carton inside the larger. There should be a gap of 5 or 6 cm between the walls on all sides. These cartons are your molds. For round containers try different size plastic bags, old plastic basins, or buckets.
- You will need concrete blocks, bricks or short lengths of heavy timber to fit against the outsides of the outer carton for support. This stops the sides from bowing out from the weight of the material. For the inside of the container, use any spare sand, soil, potting mix (anything bulky) to stop the inside carton caving in. Fill up the inside carton progressively as the walls are built up. If you are using plastic bags for molds, place 4 cm wide adhesive packaging tape around the outside to prevent bowing.
- Pieces of broom handle, branch or 25mm plastic pipe about 5cm long are used for drainage holes. These can be carefully removed later. One or two holes are sufficient for small potsfor larger tubs and troughs at least four drainage holes are needed.
- 2 parts peat
- 1 part sharp river sand, moderately fine, but not beach sand (because of salt and it is too fine)
- 1 part cement
- Plastic Sheet 1.5 x 1.5 meters,
- Wheelbarrow (optional),
- Trowel or spade, rubber gloves,
- Tamping stick, 50 x 50mm about .5 meter long,
- Wire brush
- Water container or hose
Follow these steps:
- Lay the piece of plastic sheet on the garage floor. Place the large carton in the middle of it.
- Place the concrete blocks against the outside of carton. Mix the ingredients in a wheelbarrow or on the floor. Quantity depends on the size of the desired container. After mixing the dry ingredients thoroughly, add sufficient water to make a sticky stiff mixnot runny, but about mud-pie consistency.
- Stand the drainage plugs upright on the bottom of the carton and place a layer of the mix on the base and tamp it down giving special attention to the corners and around the drainage plugs. Aim for a thickness of 5cm for small to medium size pots.
- Take your smaller carton and place it on the layer of mix in the bottom of the larger carton. Make sure it there is equal space on all sides. Then one quarter fill it with sand or whatever you have. This will stop the inside from bowing in and the carton floating up. Now, fill up the wall space between the cartons. Use the tamping stick to work it into the corners as you go to get the air bubbles out. Make sure you tamp the outside walls well. Keep building up the sides with mix, adding sand to the inside carton for support until you have reached the desired height. Leave it for at least 24 hours.
- Next morning scoop out the sand from the inside carton. Then carefully peel off the inside wet cardboard and discard. Remove the concrete blocks and carefully finish peeling away the outside cartondon't worry about the bottom.
- DON'T TRY TO MOVE OR TIP THE CONTAINER AT THIS STAGE - YOU WILL LOSE IT ALL!
- Now the tricky partyou will notice that the walls are rather smooth, in fact just like dark wet boxed concrete. We want the walls to look aged and weather worn. Using a wire brush or a special scraper, we very carefully roughen the sides, top and inside rim. You may want to round off the corners and edges as well. Don't worry about a few nicks and scratches and small holes. These help to give it a natural look. You may also want to carefully scratch or press in your own design or special texture. Having shaped the outside to your requirements, gently give it a good brush.
- The container should be left for at least a week to allow it to cure and set hard. Give it a light sprinkling with water initially 3 hours after molding and thereafter every couple of days to assist the curing process. It is unwise to lift it until it's entirely set, but if you have to shift it, only do so by sliding or dragging it across the floor with plastic sheeting. The left-over mix can be used for stands for the containers. Press it into bottles or plant pots or roll it into flattened balls. Using builders' adhesive these can be attached to the container base as feet at a later stage.
Tips for Success:
If you want a really large container, try to make it close to where it will be used. Larger pots can be made by joining cartons together with plastic adhesive packaging tape. Line the inside with thin plastic sheet to prevent the adhesive integrity of the tape being lost when it gets wet.
For a large pot you should also add reinforcing in the form of No. 8 wire, or mild steel rods. Two rings, one just above the base and the other about 5cm down from the top should be sufficient.
Molding inside a container:
You can also use the same mix by handmolding it to the inside surface of plastic bowls, buckets or basins avoid using containers with any undercut. This technique is fine for low-sided vessels but not really suitable for high-sided or large pots. It is wise to coat the inside of the plastic mold with silicone spray or a sheet of thin poly to act as a release agent. Wearing rubber gloves, press the mix firmly into the bottom and sides of the mold (no less than 30mm thick) having firstly placed the drainage plugs on the bottom. Leave the container at least four days (depending on the weather) to set. Finish as described previously having carefully extracted it from the mold.
As the Hypertufa pots age in the garden, the peat will weather out leaving the surface pitted and porousadding to the aged effect. Depending on the site you decide to display your planter, you can expect in time to have lichens (dry sites) and moss (wet sites) using the surface as their home. A coating of milk, yoghurt or a slurry of cow manure enhances the early growth of moss.
Alternative Hypertufa mixes can be made by using pine needles, chaff, fine bark mulch, vermiculite and the fine debris washed up on the beach containing twigs, seaweed, shells and bones etc. All these can be used in place of peat. Materials originating from the beach should be washed to remove salt.