I've been doing this for years. Instead of a nail, I use an old stainless steel fork. I picked up a few with 3 big tines at a thrift store a few years ago. They make the hole punching/melting part go quicker.

A electric drill works well too and you can do 4 or 5 cups at the same time.

ViolaAnn said:A electric drill works well too and you can do 4 or 5 cups at the same time.

Since I don't like to burn plastic because it could release dioxins into the air I also use a drill to make drainage holes. I have a spade bit that I use and yes, can do about 4 or 5 at a time without cracking the plastic containers and/or cups. I realize that poking holes with a hot nail or other utensil seems like a small thing and may not cause much harm, but I like to be cautious.
http://www.wecf.eu/cms/downloa...

An ice pick will work, too. I use this for making drainage holes in my jugs for winter
sowing.

Your mention of the ice pick reminded me of something. I had picked up some kind of old hand tool called a 'gimlet'; I see that in addition to its intended use for starting small holes in wood it can be used for making small holes in plastic. Mine looks like the antique type pictured here:
https://en.wikipedia.org/wiki/...)

That looks like a very useful tool, Greene! I'll keep my eyes open for one at estate or yard sales.

I purchased mine at the Humane Society Thrift Store; it was brand new in a package for only $2.

I did a quick search on the internet and several places offer this type of tool in assorted sizes. Here is one example:
http://www.woodcraft.com/Produ...

greene said:Since I don't like to burn plastic because it could release dioxins into the air

Two things.

First, the "dioxins" you are referring to are polychlorinated dibenzodioxins. Those toxic chemicals can be formed when you burn certain types of plastics.

Yogurt cups are made from polypropylene (marked with a number 5 in the recycling symbol, and often the letters "PP" below the recycling symbol). Polypropylene has no chlorine in it, and when you burn polypropylene, it can not form "dioxins" (polychlorinated dibenzodioxins). The chemicals required to form "dioxins" aren't present in polypropylene (nor in HDPE or LDPE, number 2 and number 4 recyclable plastics). If you managed to burn the entire yogurt cup, it would likely release less toxic pollutants into your house than starting your car in the attached garage, or lighting a single tobacco cigarette inside the home. If you burn polypropylene, you get CO2 and H2O, maybe some CO if there isn't enough oxygen to get it to CO2, and perhaps very small traces of aldehydes and carboxylic acids. The aldehydes and carboxylic acids will also form in polypropylene if you expose it to sunlight or any UV light source.

Second, heating a 'hole punch' tool (nail or fork) to 350F or 400F to melt holes in polypropylene won't burn the plastic. The ignition point for polypropylene is nearly 700F. There's a very wide range of temperatures that will melt, but not burn the plastic used in yogurt cups.

I guess the thing we should really be talking about is the (re)use of of yogurt cups to start seeds. I think it's a great idea and I've also done it for years.

Sound like the large fork could also make holes in several cups at once. I'd venture to guess I could find a used one at the Sally Ann store near me.

For the good information about dioxins.

greene said:
...I realize that poking holes with a hot nail or other utensil seems like a small thing and may not cause much harm, but I like to be cautious.

I was agreeing with the person who uses an electric drill. Mine was a positive post. I did not say that dioxins would be released only that they could ... but thanks for jumping on this. Lots of folks will benefit from such a detailed and informative post.

By the way, I burned my thumb today just lifting up a glass that held a burning candle ...which is another good reason that I avoid things like hot nails and melty plastic.

ViolaAnn said:I guess the thing we should really be talking about is the (re)use of of yogurt cups to start seeds. I think it's a great idea and I've also done it for years.

Sound like the large fork could also make holes in several cups at once. I'd venture to guess I could find a used one at the Sally Ann store near me.

Sharpening the tines helps a lot.

It also helps to put the cup on a block of styrofoam or on top of a juice glass and punch through the bottom while the cup is supported from underneath, but where the punch has space (or foam that it can penetrate).

I usually only poke holes through one or two cups at a time. It's just easier to push through that way, and a lot easier to pull back out. With a bigger stack, sharp tines will go in fairly easily, but the cups shift and grab and it's very hard to pull your "punch tool" back out of all the layers.

greene said: For the good information about dioxins.

You're welcome.

greene said:I was agreeing with the person who uses an electric drill. Mine was a positive post. I did not say that dioxins would be released only that they could ... but thanks for jumping on this. Lots of folks will benefit from such a detailed and informative post.

The point of my post is you couldn't get dioxins from burning a yogurt cup. Only chlorinated plastics can release dioxins (and PCB's, and other chlorinated "really bad, toxic stuff") when burned.

Most yogurt cups are made of polypropylene. I see the original post of this article shows pictures of a polystyrene yogurt cup, with a "6" in the recycling triangle and the letters "PS". I didn't know that yogurt was ever put in containers made of polystyrene, I wouldn't eat from a container made of that. Neither polypropylene nor polystyrene contain chlorine, so neither will release "dioxins" or other toxic chlorinated compounds when burned. Just like you can't build a brick house if all you have are logs, you can't get chlorinated "dioxins" if all you have to burn is hydrogen, carbon and oxygen.

Actually, most recycled polypropylene (and a lot of recycled LDPE) goes into artificial fireplace logs. So, in the real world, people burn used (recycled) yogurt cups (and milk jugs and other food containers with "4" or "5" in the recycle symbol) all the time.

Really, I don't mean to jump on you. I just get frustrated when I see misinformation repeated and passed along as though it's a fact. Misinformation like "burning any plastic releases dioxins," which is a mostly false statement.

greene said:By the way, I burned my thumb today just lifting up a glass that held a burning candle ...which is another good reason that I avoid things like hot nails and melty plastic.

I can't help you there. I would suggest a sharpened fork or nail to poke holes in your yogurt cups, but even those can be dangerous.

Are you happy now?

You've inspired me to change my signature line for a while, Greene.

Good one.

[quote="ViolaAnn"]I guess the thing we should really be talking about is the (re)use of of yogurt cups to start seeds.


Guys, I use those little paper Dixie bathroom cups to start seeds in, not the waxed ones, but the really small paper ones that are not waxed. You can write on them with a sharpie pen and label them as to what you planted in them. Then when your plant is ready to transplant, you can plant the whole cup, it will break down easily, as it was not waxed and it softens easily when exposed to a lot of constant moisture, so by planting in moist soil, it will just break down. Works well for me, and no plant transplant shock.