How To Make Cement Planters
“What on earth are you up to NOW?” — Husband was not too happy when he saw me scratching about in his building materials. I’d read about making pot plant containers from quick set cement and was interested in giving it a try. Christmas is just around the corner and with it, a list of special people all deserving a gift saying how much I value their input in my life. I was hoping to be able to make some gifts that were just a bit more special than something from the high street. I also think that these could make some great end of term gifts for favourite teachers.
Going by what I had read on Pinterest and other DIY sites, I needed a mixture of some sort of cement, sand, and usually something to add bulk (but that was lighter than the stones and gravel usually used in concrete). ‘Vermiculite’ was a word used in a number of blogs. I thought it was the type of light wood shavings you buy for bedding for hamsters and other pet rodents! I duly added a bag of this to my materials stash!
The Cement Mixture Debacle…
I managed to get Husband’s interest and we set about testing anything from tile fixative, plus or minus building sand, sea sand (when the building sand ran out), tile grout of various sorts, plain cement and quick set cement, and ready-mixed cement. It was such good fun but in the end, I had only two real winners: ready-mixed heavy duty tile grout and ready-mixed cement and sand (plain or quick set — there’s no real difference other than time). Wood shavings certainly gave more lightweight results and I really thought I was on to something!
Experts I have since spoken to questioned the long-term lifespan of wood shavings, so please bear this in mind if you are planning to make some family heirlooms! They also point out that the salt in sea sand will cause corrosion so best to stick with builders’ sand!!
Moulding Your Cement Planters
The next interesting phase was finding moulds. You need a larger mould to form the outer shape and an inner one to form the ‘hole’. There is always a risk that you may have to break these moulds to set your creations free, so stick to all things disposable! Some people use a variety of decreasing sized container moulds simultaneously, starting with one large container and putting the smaller moulds into each other. You’ll get a number of planters from a single session and save on the number of moulds needed. Can’t wait to try this myself!
I found that for small to medium-sized moulds, it was best to make the gap between the outer and inner mould about 2.5cm – 3cm. When I get to make larger planters, this thickness will increase.
There are various remedies suggested to deal with the problem of the cement sticking to the moulds. We had to peel our first attempt off after gently sawing to get a starting point. I tried cling film, Vaseline, and cooking oil to deal with the sticking cement problem. Cooking oil gets my vote!
So, after all this, how would I recommend making a cement planter?
How to Make a Cement Planter
- Cement – either quick set or normal Portland cement – smallest amount (500g) to start off with will do. This also comes ready-mixed, in which case you won’t need the builders’ sand below
- Smallest bag of builders’ sand and some fine gravel to use for bulk (if you buy ready-mixed cement or concrete, you won’t need to buy sand and gravel separately)
- Water to mix
- Moulds (see notes above)
- Gloves – essential – cement is very hard on the skin and can burn it!
- Bucket for mixing
- Trowel and/or old wooden spoon for mixing
- ‘Pokey’ tool for releasing trapped air bubbles (back of abovementioned wooden spoon also does the trick)
- Medium and fine sandpaper
- Drill for making drainage hole
- Cement sealer
- Materials for decorating and sealing your masterpiece
Begin by planning the shape of the planters and what moulds you will need to achieve this. You will never look at plastic and glass containers and packaging in the same way again! Sturdy cardboard that has been taped down at the edges also works well.
Spray or paint cooking oil onto the inner surface of the outer mould and outer side of the inner mould.
Thoroughly mix the cement, sand, water, and any other ‘bulking’ agent if you are using it. I used a ratio of one part cement to two parts sand and four parts bulking agent. If you are using the ready-mixed cement, you won’t need to add sand or bulking agent. Follow the instructions on the packaging.
Slowly add water (about two parts), mixing well. Remember your days of mud pies? Mix until you have what someone described as like crunchy peanut butter — it needs to keep its shape but not be dry.
Pour/spoon the cement into the outer mould until it’s about three-quarters full, and then twist the inner mould into place. Some cement may overflow out of the outer mould — return this to your mixing bucket. Use your designated poking tool to release air bubbles in the cement. Make sure your surfaces are level and smooth and that there is about 3cm between the inner and outer mould at the bottom.
Using the cling film lining method — ready-mixed cement mix on the left, with bulking sawdust shavings on the right.
Allow to dry (at least 24 hours). It should feel firm and solid to the touch. Remove the mould by gently by easing it off. If the cement is stuck, make a cut in the mould and then peel or break it off gently. If the oil has been evenly applied, the mould should come off easily and can be used again.
The planter should be left to ‘cure’ for at least 7 days before sanding and/or decorating. Water can be retained in cement mix for long periods of time, so be sure your pot is well and truly dry before you begin decorating!
The cling film worked well getting the inner mould out, but nothing would budge the outer mould until we cut a slit and then peeled it off!
Drill one or two drainage holes with an electric drill at this point.
Consider sanding the surface to get a smoother finish.
Sanding made such a difference.
Drainage hole drilled but not centred!
There are PVC cement sealers available to seal the surface of your planter before beginning to decorate, if you wish.
The sky is your limit for decorating your pot, ranging from the very simple (such as just adding an area of colour) to intricate designs and embellishments. I used acrylic paint for a white area, with a bronze coloured border using a paint pen. The smaller pots were given a white acrylic colour wash and then I used a gold paint pen to draw on the simple star and circular motifs. I used a little of the gold colour to highlight the edges of these containers.
Once happy with the decoration, I sealed my handiwork with two coats of clear matt varnish.
I found at this point that I had to restrain myself from starting the whole process again as my head was so full of ideas of how to do it all differently and better! I can’t wait to make my next batch of pots — this could become an addiction!
Finally, I potted the containers up with some of my favourite succulent plants. Some of which had most conveniently propagated recently and whose babies could now be rehomed in smart new pots.
I hope you have enjoyed reading about my introduction to cement container making! Perhaps you will give it a go as well? Remember to let me know what you think and how you got on with your own recent ‘makes’. Look out for me on Facebook and ‘Maz Makes’ online. ‘Til next time — Maz