I love concrete. I love the feel of it, the coolness of it, and the strength of it. A few years ago, I was lucky enough to be invited by my sisters garden club to take a course in making a HYPERTUFA planter. It was a lot of fun. Not like the dentist fun, nothing can compare to that, but like getting dirty fun! Hypertufa planters are much lighter than a concrete planter of the same size, which makes them much easier to move. Since the course, I have made numerous projects with my daughter and my sister.
The plant pots were easy to make. My mix was
1 part vermiculite or perlite
1 part peat moss
1 part cement *( must use Portland cement) not ready mix
I started with 1 part water and started mixing it in a wheel barrow. Please ensure you have rubber gloves, a mask and eye protection. Cement powder can be nasty in your eyes and lungs and is especially hard on your hands.
You don't want a sloppy mix; it actually is kind of on the dry, stiff side so that it will hold its shape while packing it against the sides of your plastic plant pot mould. If you need more water, add it gradually. If you have added too much water, just add a handful of each until you get the right consistency. Just keep the mixture stiff. I used a shovel to start with, then used my gloved hands to finish mixing. A large planter will use about 1 1/2 ice cream buckets of each ingredient. The mix should hold its shape if you form it into a ball.
For this planter I actually used one large and one smaller mould, but this isn't necessary as you can mould the inside with your hands, although having a smaller one makes it neater. I filled the large mould up half way, and placed the smaller one inside forcing it down. You want to keep at least a 2 to 3 inch thick bottom and about two inches on the sides. Pack the sides of the mould firmly forcing the mixture down the sides to ensure it is well packed.
After it is packed in the mold, cover with plastic to keep it moist. You can spray it with water to dampen your project. You want it to dry slowly. After about four days, you can remove it from the mold.
Back to the first set of pots I made, as the one that I blogged about wasn't ready to un-mold yet.