Selling plants by post

I wrap the roots in damp kitchen roll, then cling film. Then I wrap them in corrugated cardboard sealed up with sticky tape. I sent another member some Hellebore plants like that - they only cost £1.45 to post.

Sadly, unprotected in a padded envelope, they might well get squashed or bent.
You could try a piece of cardboard in the padded envelope if you have to use one.

How big are the plants you are trying to send? I wouldn't even consider sending a plant in a padded envelope or jiffy bag as the plant will be squashed and damaged! How many do you send on average per requisition?

plastic fruit packaging from the supermarket will make a good protection once ready for the post. this is similar to how T&M post them.

I've received plants from an eBay seller packaged in a plastic coke bottle with the top and bottom cut off. Protects the plant and 'recycles' the bottle!