Plastic pots usually come with holes but when I used the black plastic flower pots used in supermarket I used a hot poker to make the holes. A photo of your pot would be helpful. OH used a drill to make some holes too.

in the past I have used a drill too. if they are proud inside the pot I just left them and filled the bottom with crocks/gravel so it was level with them. it seems to serve as a small reservoir of water for the pot.

Easy. I simply hold the tip of a long nail with a pair of plyers over an open flame (the gas burner in my case). When the nail glows orange hot, you can pierce through the bottoms of all the plastic pots at once if you stack them together. Works really well on plastic cups if you need a lot of pots for seedlings, etc,

I just use my basic Black & Decker drill with a wood bit fitted - if the pots are shiny/slippery, safest to stick some masking tape where you want to drill first, stops it slipping.

The nipples wouldn't need to cut off absolutely flush so a craft knife would do it.
I've used BG's hot nail method enough to know that you'll need very good ventilation if you can't do it outdoors!!

You'll get a puff of stinky smoke so be near an opened window. It's done in about 20 seconds. The hot nail will go through the pots like butter. Be careful!

Thanks everyone for the tips on how to do it. I wish I had a drill then t would be easy. Bathgate, the idea of stacking pots to pierce with a hot nail is ingenious if scary.
i am unable to post photos at the mo.

I use an old fashioned hand drill where you have to turn it manually. I turn the pot upside down and the drill goes through easily and will do 2 or 3 pots at a time.

I use an old fashioned butchers skewer heated in a gas flame. Just changed to an induction cooker so guess it will be drilling next time.

I wish i had a drill of any sort Pennyfarthing. i did have one but I took it to work and it was chucked out (long story). Stera, my OH had just suggested a knife sharpener (I have one that never gets used) which could be ok. Like a red-hot poker as Scotsgran suggests. I've tried cutting the nipples off with my swiss army knife but the plastic is just too tough. I bought these pots to make life easier due to decreased mobility!!

Do take care Merlin and take heed of the warning to ensure wherever you do it has good ventilation. Outside is best if you can do that. The heat melts the edges of the holes and there should not be any sharp bits which means they will not split as they might if you use a knife. I have a small heat torch as used by cooks to melt sugar etc. It works on lighter fuel (gas) and works well to make holes. Good luck.

I use an old soldering iron on an extension cord so I can go outside.

Thankyou Scotsgran for your consideration. I've done a few with an old lighter for gas cooker. It worked but soon ran out. So then I tried a skewer held over the gas flame and that worked too but involved much running in and out to the kitchen and the patio.
I wish i had more tools Wylie but my toolbag is a bit spartan. My partner doesn't even know where it's kept.
Well so far, I've done two pots - only four to go. The pots are incredibly sturdy. I'm still pleased with them because they look good and were a bargain.
You've all been so helpful.

I do the 'hot nail' right in my own kitchen next to the gas stove. No running about at all. It's all done in less than a minute.

I think I'll try that Bathgate as it will be much easier.

I am not trying to be provocative but the plastic cups which are used for Bathgates method and the incredibly sturdy pots bought by Merlin will be of different plastics and need to be treated as such. I would not be concerned burning holes in plastic cups in the ventilation as described by Bathgate but I would never risk my health for the sake of making holes in sturdy pots. I would rather plant my plants in a proper plant pot which comes ready pierced and fit that inside the attractive pots. Just for interests sake how big are the pots you want to make holes in? I dk which plants you want to put in the pots but using a lining pot can be of great assistance for us older gardeners as they can be interchanged with little effort. Eg. summer bedding or overwintering bedding and bulbs can help us have the pots full of colour all year.