Hypertufa (n.): An artificial and lightweight stone that gardeners can create from a recipe and mold into plant containers, troughs and any other shape.
If you mention hypertufa to a non-gardener, you would probably get a blank look. But in the gardening world, it is very trendy and a sign of a serious gardener is the number of hypertufas scattered in their garden.
Perfect for planting miniatures and alpine plants, hypertufa troughs fit into any size garden, large or small. A man-made imitation of light weight tufa rock, hypertufa is a mixture of 3 things: perlite, peat moss, and portland cement. Some fiberglass fibers used for strengthening is a good idea but not essential.
Purchasing a ready-made one is always an option but pricey. A medium 15″ trough could set you back around $100, whereas the materials for constructing several will be around $30-$40. And the fun involved is something that pulls people together for a hypertufa party, complete with wine and lots of food.
When I plan on making hypertufa, I also plan on inviting people and having a party. More hands are helpful in making this a fun event. Hypertufa partying takes some planning and preparation but is worth it once everything starts to happen. ‘Mise en place’- the cooking phrase, having everything in place, is paramount here. You don’t want to be running around gathering supplies while everyone is waiting and concrete is being mixed.
I tell my guests that I will provide all the materials for making if they bring a mold on a piece of plywood, a face mask, and rubber gloves. Molds are simply a tupperware bowl without a lip, an old styrofoam ice chest, cat litter container, or a sturdy box.
- Blue Tarps– I use a couple of blue throw-away tarps to lay on the ground which makes cleanup a breeze
- Face Masks and Gloves– Face masks are essential to keep you from breathing portland cement dust which is toxic; Rubber gloves keep your hands clean
- Mixing Tub– I use an old cement mixing tub, but any wide mouthed plastic container will do like a small baby pool
- Mixing Tools– Use a shovel or sturdy garden trowel
- Old Trash Bags or plastic film– Using plastic between the container and the hypertufa mix when packed into the mold makes the unmolding process easy: an alternative is cooking spray
- Plywood Pieces– The pieces when wet are heavy and hard to transport without a study board underneath it
- Heavy Duty Clothes- Wear heavy duty work clothes as this can get messy
- Wire Brush-Once you remove the hypertufa from the mold, you can texturize the outside with a wire brush while the hypertufa is still wet
- Molds-Any form that you use will be trashed afterwards! Styrofoam ice chests, plastic containers, sturdy bowls or boxes can be used. Think small and portable. Choose anything with a top wider than the base and avoid 90 degree sides that makes it difficult for the hypertufa to slide out. Ice cream tubs are excellent.
- Portland Cement-one 96 pound bag which costs around $20; this will make lots of troughs, at least 12 good sized ones; there is no substitute for this-you must use Portland Cement!
- Peat moss or Coconut Coir– 3.8 cubic feet bag of peat moss will cost around $25: alternatively you can use a compressed block of coconut coir- 4 bricks for $25 (this is a more sustainable choice)
- Perlite- one 4 cubic bag costs around $15; alternatives are sand or vermiculite
You can get the perlite and the peat moss in smaller sizes if you just want to make a couple of troughs, but the Portland Cement only comes in the monster size.
Using a small bucket for measuring, I use 1 part portland cement to 1 part each of the perlite and peat moss and mix these thoroughly into a mixing tub, breaking up lumps.
Enlist everyone at this stage in mixing and breaking up the lumps to make a uniform mix. Next have your hose handy and start adding water in increments, mixing after each addition until the mixture will hold in a clump in your hand. It resembles wet cottage cheese or cookie dough at this point. If your mixture is runny, this can weaken the integrity of your trough.
Molding – The Fun Begins!
Molding and forming the trough is the fun part. Everyone brings their mold staged on a sturdy piece of plywood so that they can transport it home easily. We first covered the molds with a piece of old trash bag which greatly simplifies the removal of the mold from the hypertufa. After donning their gloves, people dove into the tub and grabbed handfuls of the mixture and start covering their mold with a two-inch layer of hypertufa mixture. It is important to have good coverage so that the walls are sturdy and won’t cave in. I had dowels ready for people to insert through the bottom of the troughs for drainage holes. Also, be sure that your hypertufa is level on the bottom so it sits without rocking. A level is helpful for this.
A hypertufa made in a Styrofoam ice chest
After everyone had thoroughly coated their mold and smoothed the bottom and sides, we took a break and admired everyone’s creations. At that point, the troughs are ready to take home for curing. Curing simply means that the cement has to dry slowly to avoid any cracks forming. To do this, simply mist the container once a day and cover the trough with a piece of plastic to hold in the moisture. You can’t rush this step and it will take a few days to be ready for unmolding. Once unmolded, the hypertufa has to be cured (hardened) for at least several weeks.
If you love the natural look, you can add a moss milkshake (moss plus yogurt or buttermilk blended together) to the exterior for a weathered look.
Before planting, I thoroughly rinse the hypertufa with a hose or dose it with a mixture of vinegar and water as the container will leach lime into the soil of your plants. Then you can start the fun of planting your new container. Your completed trough will last for years outside and will eventually grow moss to make it look like an antique planter without any help from the moss milkshake.
I have had hypertufa container for over 25 years. I like to elevate them so that they drain properly. A good way to do this is make some hypertufa ‘feet’. These are just hunks of hypertufa (use any extra that you have left) that you can mold into chunks that will prop you container up. Elevating your hypertufa makes it stand out and drain better.
Hypertufas are naturally porous and will drain somewhat without the drainage holes, but I always add a few. Succulents are my plant of choice for a hypertufa as they prosper in shallow containers, but small conifers do well also.