I have read the thread on preparing plants for shipping. I am shipping verbena tomorrow. I'm assuming it is ok to knock and rinse most of the soil off, even though these are easy to wilt.
Question on packing /sending plants
depends on the plant, I have found. And how long it will travel. I normally leave most soil on it I water it too. Cover it with wet paper towels and the use something plastic to cover around just the paper towel section. Then take newspaper to make a cone around it or the plant part.
The only time I would leave a lot of dirt is if the plant doesn't have a huge root system. If the plant has a big heavy dirt ball, it's going to beat a small plant to death in the mail. You can spritz the foliage before you roll it in newspaper and that bit of extra moisture will help during shipping.
Glad someone brought up the soils factor - I always assumed that there were restrictions on soils crossing state lines. Maybe it is not a problem for most states, but I know that California has agricultural inspection stations in all the main routes into California from neighboring states and they always ask if you are bringing in plant materials. With all this trading across the internet via priority mailings in which no one needs to identify what is in the packages, I am thinking that sometime down the road, problems will crop up. For this reason, just to be safe, I try to rinse off as much soil as possible, replace it with something like vermiculite, or just wetted paper towels for the sturdier plants. If California is the only state that is wary of agricultural pests, then I won't worry so much when I send plants out of state.
Sending to California IS a special concern! I try to send things, only grown in soil-less mix and also specify so. I'm also Ag certified so I do not worry quite as much.