Making a Hypertufa Planter

[Andy_CT]

Making a hypertufa planter

Part 1

First I want to say that I am not an overly experienced hypertufa maker. I had never even heard of it until July 2007. I got interested and surfed around the net gathering as much info as possible. I just dove fearlessly in and made several big mistakes on my first try (like trying to build a large 16x22x8" trough on the first try, not too smart!). If your really interested but a bit hesitant to try it, my advice is just do it. Start with something real small like a few small bowls. You may not want to invest in a lot of materials to find you don't like doing it later. If you can borrow some cement cause it usually comes in 94 pound bags for about $9. I know I've made at least one mistake on every single project I've done yet none were fatal.

The idea with hypertufa is to use a cement based mixture to mimic rock. Peat moss is the main ingredient in hypertufa that gives it the 'look'. If you don't use peat moss your not making hypertufa.

Additional benefits of using peat and perlite in a cement mix is that it makes the whole thing "airy" and it will act more like a clay pot. As we know this is good news for cactus & succulents especially if you live in a wet climate

Here's some of my finished handiwork from last year.

a 16x22x7 inch trough with common succulents
a smaller 10x15x6 inch trough with hardy cactus
small 6 inch bowl with a young Echinocereus

List of items used

Hypertufa ingredients

portland cement - I buy quikrete brand 94 lb bag, not sure if you can get a smaller bag
sand - I use quikrete all-purpose sand. sand is optional, see below. Your town may offer free sand but I find ours unusable as its dirty, full of weeds and whatnot.
sifted peat moss - I buy whatever is cheapest. I sift the twigs and other larger pieces out of the peat moss using a screen.
perlite - whatevers cheapest, vermiculite is an alternative.
water - its free from your faucet

other important items used

large heavy duty rubber gloves - should cover up close to elbows
goggles - you may not want cement/sand/perlite dust going in your eyes
dust mask - you don't want to breathe cement/sand/perlite dust (don't fret, once you start adding water to your mix the goggles/mask can come off)
apron/ junk clothes - it can get messy so put the good clothes away.
mixing tub - you need something to mix your hypertufa in. A wheel barrel will work. I bought a plastic mixing tub from a local company, I later saw the very same one at Home Depot and Lowes for less. Hey, if you already have, can borrow or can afford to buy a motorized cement mixer then that will make the mixing part much easier!!
measuring bucket - I work in US dry gallons and use a 1 gallon bucket to measure each item. Use whatever unit of volume you like and you can use a site like http://www.onlineconversion.com/volume.htm to convert units
spray bottle - fill this with water and keep it handy
mold - you need something to shape your mix, I'll get into that more later.
plastic drop cloths - If you want your work area clean lay down a large sheet of plastic. Also I use this same plastic to cover my molds which makes removing the mold from the hardened hypertufa much easier.
wire brush & cement tools - you need to "touch up" your hypertufa's imperfections like smoothing out edges before it permanently dries. More on this later
wooden dowels - I use these to make the drain holes
work area - for mixing the dry ingredients you need to work outside so those nasty dust particles float away. Once the mix is wet you can move it into a garage or work shed if you want.
warm weather - I've read that cement doesn't cure as well when temperatures are below 50 F (10 C). Best to do this in warmer late spring/summer weather.


Making your mold

Your mold is what you use to determine the shape of your planter. There are a million ways to make molds and there is no right or wrong way as long as it works. Look around the internet, I've seen lots of genius ways to make molds, the sky is the limit. I prefer to mold on the outside of something (like a bowl, a box etc..) , this way you get an uneven more "natural" look on the outside of the planter. Hypertufa won't stick to plastic so I cover all my molds with plastic drop cloths and tape it down all loose edges or folds in the plastic. Even if using a plastic pot or tub, like my current project, I still cover it in the plastic sheets cause I found that slapping hypertufa mix on a perfectly smooth surface can create a vacuum and might be forced to cut the plastic up to get your mold out. Another method is a box inside a box with spacing around all sides of inner box, the hypertufa mix is filled into the spacing.

Have your mold ready to go at least the day before you start as this part alone can take some time.

My mold for this project

Here I am going to make a trough out of a standard dishpan. I'm going to turn it upside down and put the hypertufa on the outside.
standard dishpan.

I then tape plastic sheets all over the pan and make sure all loose edges are taped down.



Next I lay down a large plastic sheet in the area I'm going to use for covering the mold. I used a smaller sheet and draw a line around the tub to use as a guide to get the right thickness



My mold is now ready to go.

drain holes

I forgot to take a picture but I also made 4 wooden dowels about 1/2" thick an 4" long. I covered these with saran wrap and tape it smooth. I also draw a line about two inches from an end. When I put them into the mix on top of my upside down dishpan the line will help me get the thickness of the mix applied right. If you don't want to work with dowels you can drill drain holes into your trough after it has completely dried.

Hypertufa formula

The formula I personally use is:

1 part - portland cement
1 part - sand
1 part - sifted peat moss
1 part - perlite

I live in a climate where it can easily get below 0 F (-18 C) and can stay below the freezing mark for weeks at a time. Because of this climate I add sand to my hypertufa mix for added strength. If you live in a warmer climate that doesn't see much freezing weather then you can skip the sand if you want and use:

1 part - portland cement,
1 1/2 part - sifted peat moss,
1 1/2 part - perlite

This will be lighter cause sand is heavy, peat moss is lighter and perlite is very light. There are a lot of other formulas floating around the net. I believe it has to have peat moss to be considered hypertufa.

Reinforcement fibers (optional)

I bought a bag of reinforcement fibers for cement from a local cement supply company. They are suppose to add strength to your cement mix. I really don't know much about it but I add a pinch or two to my mix while its still dry. These fibers can be a small pain to break up and mix in plus they'll float away in the wind if your not carefull. A small bag should cost $5-$10

How much material do you need?

This is a tough one. It will obviously depend on the size of your item and how thick you want the walls to be. If you know the volume that your material needs to fill up then there is a way to approximate the total materials needed. If your mold is an odd shape or is free form then you kinda have to guess based on experience. Hint: try something small and easy for your first few attempts then you'll start to get better at guessing for how much you need.

For this project I'm using a standard size dishpan here in the US. the size is 13.5x11.5x5.25 inches (34.3x29.2x13.3 centimeters). Since I want to play it safe by having a bit more material than necessary I'm going to bump it up to 14x12x5.5 inches (35.6x30.5x14 centimeters). I will be molding the hypertufa around the dishpan while its upside down.

The calculation of volume needed is a bit trickier than you might think. Unfortunately I can't do any fancy computer graphics to illustrate what I'm calculating, so I may lose somebody here. Anyway here goes. I want my walls and the bottom of my trough to be 2" (5cm) thick.

for calculation purposes the total height is going to be 5.5" + 2" = 7.5".
the total length of the longest side will be 14" + 4" = 18",
the total length of the shorter sides are 12" + 4" = 16"

The volume of the longest side is going to be 18" X 2" X 7.5" = 270 cubic inches. Multiply by 2 since there are two long sides and you have 540 cubic inches

The volume of the shorter sides is going to be 12" X 2" X 7.5" = 180, X 2 = 360 cubic inches. If you notice I used twelve for the length and not 16 cause there is overlap with the longer sides so that area was already calculated.

The volume of the bottom is 12" X 14" X 2" = 336 cubic inches, here I did not use 18 X 16 for the bottom since each side calculation was a full 7.5" in height so the bottom area under the sides is already accounted for.

Now I have 540 + 360 + 336 = 1236 cubic inches. Ok, I'm not done. Now if I use 1 part each of my ingredients for exactly 1236 cu inches its NOT going to work. The perlite and peat moss are airy so the cement and sand will work in between and a lot of the materials will share the same volume space. So mixed together they won't equal 1236 cu inches. I forget where but I found and online site that used a multiply factor of 1.65 to approximately account for this shared space. So multiply 1236 X 1.65 = 2039.4 cubic inches. I used this 1.65 factor twice last year and its pretty good. You still want to probably mix a bit extra as having a little too much is no problem but having too little is a problem. And again once you do a few of these you'll start to get the hang of guessing for material needed.

Now since I'm not sure know how to measure 2039.4 cubic inches I'll convert this to US dry gallons. which happens to be 7.6 US dry gallons. I'm going to go ahead and bump that to 8 dry gallons. This should give well enough material to mold onto the outside of the dishpan. I have a small bowl for a mold ready to go if I happen to have a lot of extra.

So ingredients used will be: 8 gallons divided by 4 parts = 2 dry gallons each item

2 dry gallons each of portland cement, sand, peat moss and perlite. This makes it real easy since I use a 1 gallon bucket for measuring. So two bucketfuls each.

Time to mix

Now that I know how much stuff I need its time to start mixing. First I fill up a 5 gallon bucket about half full with water, put it aside. I put on the rubber gloves, goggles and mask. I measure my 2 gallons of each item and dump them in the mixing tub. I then toss in a healthy pinch of reinforcement fibers. You can put your tub on a table if you don't want to bend down.

here's peat moss, perlite and sand in the tub
now with portland cement on top.

I start mixing the stuff with my hands or a small hand shovel. Swirl it around and keep going til it looks evenly mixed. Keep checking for pockets of hidden unmixed material on the bottom, they are hiding in there!! When you mix everything turns grey like the cement. Your done when everythings an even grey color. I continue to mix for a few minutes afterward just to be sure.

mixing the dry ingredients
here its now completely mixed

When I'm fully satisfied that its completely mixed I take the bucket of water and I poor approximately 1 gallon in. Work the water around until its evenly mixed in, The mix should still be way too dry at this point. Take off the goggles and mask (yeah!). Now keep adding in small amounts of water then mix it completely in before adding any more. You want to keep doing this until the mix is the right consistency. Getting the consistency right isn't too hard but you want to be sure its not too dry or too wet. The correct consistency is when you can scoop some up, squeeze it and a little bit of water runs out between your fingers. You DO NOT want it wet to the point where it will poor out like a heavy liquid. It should still hold shape when you squeeze it but be wet enough that a little bit of water dribbles out when squeezed. There is no correct amount of water to use from project to project even if you do the same mold over and over. Humidity and other factors will determine the water you need. Always add a little at a time as you get close to being correct and again always fully mix the water in before adding more. If you should happen to put in too much water the only thing you can do is to add some more dry ingredients til it gets back to normal

mixing the water in, its harder at first
splashing small amounts as you go
here the mix is "correct"

Putting the mix on your mold

Once your satisfied that the hypertufa mix is the right consistency you need to immediately go to work by slapping it onto your mold. I start by putting some along the bottom edge then put a layer on top. Then I stuff the dowels into the mix on top where I want the drain holes. Now keep adding mix along the sides working your way up and once you have enough to connect the top and bottom it should hold. Note: The mix may want to slide down on the side walls of the mold, don't panic it happens all the time to me, as long as your mix isn't too wet you should get it to hold place. If it ends up way uneven or really thin in areas, don't worry. Thick areas can be trimmed and you can ADD more mix at a later date to even it up.

applying to hypertufa mix onto the mold

Now about every 4-5 minutes you'll want to swirl all the mix around in your tub cause this is cement after all and it will start to harden up if left untouched for too long. . Also besides beginning to harden up the mix may begin to dry out especially on a day with low humidity. Have your spray bottle handy and squirt a touch in if the mix seems to be getting dryer as you go along. Ok, keep adding mix to the mold paying attention to the lines drawn around the mold and on the dowels. Once you have completely covered adding the mix on gets easier and easier but you can lose sense of what spots need more and what spots are done. That's way I draw lines as a guideline. You can also poke into it with a small pencil or something if your unsure of the thickness. As it gets more and more covered try to gently smooth out clumpy spots or tease some of the edges to get rid of a split in the mix. Its all easier that it sounds (hehe).

the mix is now fully applied, It ended up a bit bottom heavy on me as the mix constantly wanted to slide down on me. I may have to add some mix to the walls if it turns out too thin. stay tuned!

Once you have the hypertufa on the mold as planned (or close to it) now you cover the whole thing with a sheet or two of plastic and put some items around the sheet to hold it in place and keep it as air tight as possible. Now you mist your hypertufa 2,3,4 times a day, whatever your schedule allows. To do this, simply pull off the plastic, mist all over with the spray bottle, then cover it back up. The idea here is to keep the hypertufa mix slightly moist so that it hardens slowly. I'm not an expert on the subject but the chemical reaction of the cement and water forms a stronger bond the longer it 'cures'

covered in plastic

Note: You must have patience at this point, do not rush. If you try to unmold to soon it will all probably fall apart.

[Andy_CT]

Part 2 is coming in a few days.

[TimN]

Thanks Andy! I'm looking forward to making a few of these for my larger outdoor plants.

I'm happy to see you using a plug and putting the material on the outside. The box in a box method looks more difficult and I'm not sure if it gets better results.

I know a couple of concrete guys, I'll ask them about the length of cure.

I'm looking forward to part 2.

Tim

[Andy_CT]

I'll get into cure time in part 2, but unmolding is done in 2-4 days then its put back under the plastic and misted several times daily for another week at least.

As a teaser my trough is unmolded now and still in one piece

[daiv]

Wow! That is quite a lot of work! Nicely done!
_________________
All Cacti are succulents, but not all succulents are Cacti

[Andy_CT]

I may have gone a little overboard but you mentioned an article so I tried my best. Wish I had this when I started last year

[CoronaCactus]

Excellent article Andy!
Thanks for taking the time to write it.

I think i may give this a whirl and make some unusal and odd pots for fun
_________________
Darryl
Livin' la vida cacti | CoronaCactus.com | Mojave Desert

[iann]

I made a bunch of pots with various concrete recipes.


Some didn't make it. My freeze/thaw climate is brutal for weak pots. Sand is essential and larger pieces have to be wired to prevent cracking. The fibres are a good idea but not cheap. You'll have to see which mixes you like and whether you need them. I stopped using peat in my mixes, they never looked enough like stone to satisfy me and the peat makes them horribly weak. Vermiculite concretes are nice.

Curing of concrete occurs at any temperature above freezing but it cures more slowly in the cold. Below 5C you will be waiting forever just to unmould, but don't worry about the temperature dropping at night so long as it stays above freezing. Curing is faster at warm temperatures but the concrete will be weaker. Concrete only cures when it contains moisture. As soon as a portion of concrete dries then the crystal formation is interrupted and strength is lost. At a constant 10C-15C, you should expect a couple of days before the piece can even hold together under its own weight, a good week before you want to be moving it about much, and a month to really get close to full strength. You can perhaps halve those times at 20C. Some concretes include admixes, often they speed up the cure because most contractors can barely be bothered to keep concrete wetted down for 24 hours before they want to be working on it. Concrete which is not kept moist for long enough will (always) have a dusty surface, think about that cheap garage slab your father-in-law laid for you Not so noticeable on a pot with a rough surface that is often wet but a long moist cure is always stronger and there is no downside.
_________________
--ian

[cactuspolecat]

Thanks Andy, this post is very educational... from time to time I've thought of doing something like this, so it's good to get the gen, and some inspiration.

Look forward to part 2

CP
_________________
"To be held in the heart of a friend is to be a king!" ...Bruce Cockburn.


G'day from down under in Devonport, Taz, the HEART of Oz.

[John P Weiser]

Great article Andy! I knew you had it in you. You did not go overboard. I feel there can never be too much information on A "how too project". As you say jumping in is the best teacher but a little guidance can give a boost gardeners like me who have known about these troughs for years but not jumped yet. I think I'll be jumping in this weekend. Thank you for the inspiration. sierrarainshadow

[ihc6480]

Looks like a well planned write up
I agree theres never to much info on a project like this. I too am thinking about making some troughs.
Looking forward to part two
_________________
Bill

If it sticks ya or pokes ya, I like it

[Tony]

Thanks Andy! I will have to give it a go, Do you know anything about, Or have you tried adding colors to the mix?
_________________
Tony
http://www.gatescss.org/

[Andy_CT]

[ihc6480]

Don't see any reason you couldn't add coloring to them. Lowe's and Home Depot sell the coloring for them
_________________
Bill

If it sticks ya or pokes ya, I like it

[TimN]

Thanks for sharing your practical experiences, Ian.

I'm glad to hear that vermiculite works well, I've got a bunch of it and I don't put it in my cactus mix any more.

I think I'm going to give this a try this weekend. It should be near 100F so curing shouldn't take too long. I'll definitely try to keep it wet as long as possible.

Tim