As requested, here's my method for venting clay pots that don't have enough holes in them to make orchids happy. Safety first, please wear safety glasses when you are using any cutting tool, and there will be terra cotta dust, so if you don't want to breathe it, a fiber mask would be in order as well. I did my cutting in front of a window in my DH's shop and there was a nice obliging breeze blowing the dust all over the floor instead of into my face . . .. in hindsight, the little shop vac would take away the dust very nicely (but it makes such a racket!).
I use a Dremel tool with a little diamond wheel on it. You may have to use a larger wheel if you have a bigger, thicker walled pot. My pots are only a bit over 1/8in or 2 to 3mm thick. You also are pretty much stuck with straight-sided holes, because the wheel only cuts straight cuts. It would take a lot of time and patience to make anything like a curved cut.
These two little clay pots came with dying phals in them, from the Lowe's death rack. No wonder, the clay pots had no holes whatsoever, and inside each had a plastic pot as well. Soggy moss, hello-o! You can see my first attempt at a square hole in the bottom of the pot was not very tidy. I've improved my technique since then. The wheel cuts best if the clay is dry. Moist clay will gum up the wheel and you'll need to rinse it off during the operation.
Turn on the tool, I use speed setting 7 (the tool has 1 to 10) and very light pressure to keep the tool, wheel and pot from overheating. The clay is not hard, but it is fairly dense. If you see sparks where the wheel is cutting, you are pressing too hard. Don't try to go fast, it only takes about 30sec. to make each cut. If your Dremel tool starts to get hot, stop and have a cup of tea while it cools down.
I like to make little slanted rectangles (parallellograms) for those of you who are into math. So I cut two parallel sides about 1/4in. apart. Then I make the end cuts to break out the piece on the inside of the pot because then you don't see the extra cuts.
You can make squares or triangles (see below) rectangles, or star shapes, whatever turns your crank. Don't make the holes too big, though, or your bark mix or other medium will escape out the holes. Hmm, star shapes would be fun for gift pots at the holidays . . . I think I'd draw the star in pencil on the pot first, rather than try to freehand it. Or make a little pattern.
Sorry for the poor picture quality here, it was hard to get the light inside the pot while shooting with the camera in my other hand.
After I have cut on all sides of my opening, I gently tap the piece with a light metal tool. This little crescent wrench worked great.
Note, the clay gets a little thicker up near the rim of the pot, and of course the "collar" of the pot is much thicker. I don't make vents in that part, but if the pot is tall like this one, I do make the holes fairly high up the sides. (hey, they were "free" pots!)
So I did make a triangular hole as you can see above, then went back and tried a star. The 4-point star was easy - make a diamond cut-out first then make the side points after. A five-pointer would take at least 10 cuts, so I didn't try that yet.
I'd advise not to make the holes too close together, as every hole will weaken your pot a bit. I was thinking a row of diamonds would look great, or narrow triangles with one pointing up and one pointing down.
Anyway . . I digress as usual. Here are pictures of the tools you usually find in the kit that comes with your Dremel tool. You can use a sanding wheel to dress the edges of the holes you made if you want to. The edges are a bit sharp, but not sharp enough to cut you unless you really grabbed an edge hard.
The dark red cutting wheels cut great, and would work for a thicker walled pot, but be very careful not to wear them too thin as they tend to break and fly apart. The big black cutting wheel made the tool overheat pretty quickly.
And here I was thinking it might have been you who suggested using the Dremel tool, Mj!
Keep cruising the death rack at Lowe's - sometimes the pots are worth what they're charging for the orchids. I got these two for $3.75 each, and the phals that were in them are still alive, and recovering!
I also got a nice 6in. square bamboo pot with a catt in it for $5 and a square glass container (which makes a nice vase but is a death sentence for the poor little orchid that was in it) for $3.75
Elaine, I'll have to take a pic of the bamboo pots SO has been making for me. His crews had to clear out a big patch of that wide bamboo and brought home a bunch.
He's used the Dremel on it to make vents around outside edge also.
He read this post and he needs to get the diamond wheel attachment for the clay. ( surprised he didn't have one since he's got some much out there)
I've got some pretty ceramic pots too w/o drainage that came basically free with some plants off death row also so may give it a whirl with them.
Yes, be careful with the glazed pots. Even the so called low fire turn the glaze/clay to a coating of glass. It will chip and possibly shatter. I use a diamond drill bit in a drill press to put drain holes in the bottom. The bottom is the strongest part of the pot usually. I do not hold the pot and the bit must be kept wet. Even then I have had pots just shatter. Never a problem with terra cotta if you follow Elaine's safety rules.
I needed some very small pots for a couple kekis. I had some of those plastic containers Crystal Light mixes come in. I cut the top off and had a 3" bottom left. Took a mid-size drill bit & drilled holes in it. So far these are making great little pots.