Yes, there are molds by which you can purchase for your DIY hypertufa planter but………there are also things sitting around the garden shed and kitchen that can easily be turned into a mold. Below are the directions for three commonly found items that can be turned into molds in a few simple steps.
Prior to going into the mold making process, one must understand the advantages of using these molds verse bought ones. Many of these premade molds have not completely thought about how to get the hypertufa out after it has dried. This has been taken care of in the design of each one of these molds.
Mixing Bowl Mold
If you are looking for a “bowl-shaped” hypertufa then this mixing bowl is the technique you should choose. What you will need for this project is one large bowl with a flat bottom, which will be the size of your pot and a smaller bowl. The smaller one will be the planting area of your hypertufa planter.
Beyond the two bowls, you will need a sharp knife along with some type of strong tape.
Once you have your supplies, test the bowls by placing the smaller one inside the larger one to make sure that is the look you desire. If the answer is yes then you are ready to create your mold. This process is simple. Cut straight down from the top to the flat bottom but do not cut through the bottom. Repeat this process three to four more times. At this point, you should notice that the “flaps” lay down. This is the goal so that you can simply lift out your dried hypertufa planter.
When it comes to creating your mixing bowl hypertufa planter, tape up the sides to form the mold.
Styrofoam Cooler Mold
In this mold type, you will need two Styrofoam coolers. As before, you will need one Styrofoam cooler that is larger than the other and this will form the outside of your hypertufa planter or English trough. The second cooler will make the inside dimension of your planter.
Once you have your coolers, the next step is to create the mold with the largest one. Beyond the coolers, you will also need a knife and toothpicks. To begin the process, cut down the sides of the cooler to the bottom. At this point, you have two choices. One technique is to cut all four sides of the sides of the cooler so that you have five pieces total. Another choice is to just cut the sides and leave them attached to the bottom. If you are planning on making a large English trough, I would recommend the first approach to make removing the planter easier.
Once you have your hypertufa “mold” cut, put it back together by pushing toothpicks along the edge of the cut sides. Next, recreate the Styrofoam cooler by pulling up the sides and securing by pushing the toothpicks into the other side. If this is a challenge, simply pull up the sides and secure by pushing toothpicks through both sides of the corner. Repeat until the cooler is reassembled. To make sure the sides stay together, seal the corners with a strong tape.
Disposable Red Cup Mold
The easiest of all the mold designs is the disposable red cup mold. There is really nothing that needs to be done except getting two cups. Unlike the other molds, there is no need to have one smaller than the other but that is an option. The other thing you will need is some type of lubricant that will keep the inner cup from sticking. One suggestion is petroleum jelly, which can be rubbed on the other inner molds described previously. When using this technique, all you need to do is to rub the outside of the inner mold prior to placing in the hypertufa mix.
There are several different formulations for the hypertufa mix. One of the easiest ones consists of Portland cement, peat moss, perlite, and reinforcing fibers. The amount depends on the size of the mold but in general the formulation is two parts Portland cement, three parts sifted peat, three parts perlite, and a handful of reinforcing fibers. When following this recipe, it is very important to sift the peat moss to remove sticks and such. Doing this step will create a smoother hypertufa mix. Also, make sure to wear a mask, gloves, and a clothing cover like coveralls. The reason for this is the fact that this mixture can be somewhat irritating to the skin and lungs.
Once all the ingredients are in a container, mix completely. Next, add water slowly. The amount of water cannot be prescribed because there are two factors that affect the amount. The first one is the dryness of the peat moss and two the humidity. In doing so, add a little water and mix. Continue with this process until your mixture smooth. Once that has happened, scoop up a small amount and squeeze. What you are looking for is that the mixture sticks together and a little water drips out of the bottom. If these conditions have been met then you are ready to fill your chosen mold. Since the hypertufa planter will need to cure in the shade, it is a good idea to fill in this type of environment.
After your mold has been filled, place your center mold in and push down. Remove any excess hypertufa mix. Cover the mold with plastic to cure for 36 hours. Once this time period has passed, remove the plastic and scratch the planter with your fingernail. If you can scratch the surface with your fingernail then you will need to cover the planter again and allow it to cure for another day. If the planter passes the fingernail test, scratch with a screwdriver. Once the tool scratches the surface, you are ready to remove the planter from the mold. After that is done, remove the center mold. Place in the shade and allow to cure for three weeks.
Prior to planting, you will need to remove the lime from the Portland cement. This is easily done by filling the planter with water and allowing it the water to work its way through the porous container. Continue this process for ten days.
When the ten days have passed, the planters are ready to plant. Even though this planter is porous, you will want to create drainage holes in the bottom with a masonry bit.