Casting concrete spheres requires filling up the spherical mold with cement. Learn how to cast garden sphere molds to make garden spheres in this free landscaping video.
Now we are ready to start casting our concrete spheres. We are going to be using the cooking spray to lubricate the molds. So we'll start by spraying the mold slightly in. And what I have here is a small lid, and I'm going to use it to hold the mold from tilting; you can use a can, and this is almost perfect here. So, we're going to fill up this one, not all the way through, and we'll fill up the other ones, and we're going to cast them one all inside the other. Fill up little bit of it and kind of bounce it. Next we're going to take the 12 inch, this one we're going to lubricate inside and outside. Now they're going to sink inside each other, as you see how it's sinking. No rush on the lower one, go ahead and work with the upper one. As much as we fill it up, it will start sinking. And we try to keep it centered at this point. Looks to me slightly more. Okay, that looks good. Now we're going to go for the third one. So we'll go ahead and set it in the center, and keep adding the concrete in it, and shaking it. It looks like a tree at this point, but each one of them is going to sink inside the other. And the result, three half spheres at once. So we're going to keep tapping it until they sink in, and pretty much the concrete will come all the way to the rim of each one of them. And sometimes you bounce it like this, some shaking. It's all working out, see how it keeps going down. And try to look at it for every corner, see if it's nicely centered. Okay, we're going to finish it up pretty much here. As you see the other ones almost to the edge, the last one it still needs a little bit of smoothing at the top but it's almost done. And even if the top is not smooth, because when you mortar them together you're not going to see the top. If you decide that you want to create a bubbling fountain, what I recommend you cut a piece of tube, and you put it in here and you embed it in the concrete at this point, and later when it's dry you can remove it and you will have a hole through the whole sphere, and that's where the water will bubble out through the sphere. So pretty much, what you will need to do after, is in an hour or two, you come outside and you twist these, like this. By twisting them, you're pretty much disengaging the concrete from one to the other; couple of hours later you can come and do the same. After all it's done, these they need to set in the mold for 24 hours before you un-mold them. And later you will try to shake them, and un-mold them and put them aside. Pretty much 24 hours out of the sun will do it.