Please write the regulations to ensure the greatest likelihood that the customers will read and understand the warnings. This means that the written material should be printed and delivered on a separate document from other materials. It should be in large enough font to be accessible and should clearly and prominently spell out the consequences of planting invasive plants to the local ecosystem, including degradation of habitat and loss of birds and other wildlife. It should explain that people may not notice the problem in their own yards because the seeds and berries are often carried far away into natural areas. It should also explain that planting these plants causes harm to neighboring properties and to future owners of their own properties. It should include photos of plants such as Asian Wisteria strangling and killing trees, Callery Pear displacing natives, and of shorter plants taking over the understory.

It should also spell out who to give the information to if the customer is not the property owner. Many property owners are large commercial entities, so simply mailing them a letter will not be useful. The information needs to go to the decision-makers.

Thank you for working on this!

Invasive species should not be sold at all.  According to the Virginia Department of Forestry, Virginia spends $1billion dollars per year battling invasive species.

But, since this is the best we can get for now...

This written notification should be 8.5x11 inches, 16 point or larger font.  There should be no space on the page used for advertising for the tradespeople.  There should be a separate notification for each species, including information on that specific species.

The page should include:

1. the harm that the species has done in Virginia
2. the $1billion dollars per year currently being spent to battle invasives. 
3. the potential for harm in nearby areas, including both neighboring yards and wild areas nearby.
4. how the plant could spread to nearby areas - birds spreading seeds, runners, wind, etc. 
5.  a picture of the plant in a wild area, illustrating the harm done by the plant, with a caption describing the image.

A bonus: Virginia native alternative plants should be listed.  The homeowner could then ask, "why can't we just use this other one?"

As a student of Ecology and teacher of children I have learned that ivasive plant species take the place of native plants that evolved in Virginia thus providing both food and shelter to other species that evolved here also. The invasive plants species do not provide critical services towards the survival of many insects that other species such as birds and amphibians like frogs and salamanders. Fewer species can live in our commonwealth than before these invasive species were introduced in a misplace choice for a certain look and no insect damage showing. We actually have less alive because they can smother other plants, useful vines and even trees creating a virtual monoculture and even overwhelm buildings and utilities. Consumers need to be warned of the dangers of invasive plants in their gardens because they can escape to their neighbors or ecologically valuable public lands costing many hours of labor and expense to remove. As a certified Master Naturalist I have spent countless hours over the last 15 years removing English Ivy that replaces food and shelter for animals and insects. We clip it from trunks to prevent it from spreading, overwhelming and killing trees. By seeds spread by unwitting birds Porcelain Berry  vines, while superficially pretty, also overwhelm and replace trees, shrubs and other useful vines. The list is long. I depend upon our knowledgeable employees to identify all those that threaten the quality of life in our Commomwealth. 
Thank you for your time and care for all that lives in Virginia including the people who enjoy the animals that will benefit from fewer invasive plants.

These plants are invasive (list). Invasive species cause economic and environmental damage.

Invasive plants are a serious concern ecologically and economically yet nurseries continue to sell them within Virginia likely because they are cheap to propagate. While labeling is likely insufficient to address the issue in full it would at least help raise awareness on the issue. I support Margret Fisher's comment on how to make sure such labels are of value in raising awareness and suggesting alternatives as commenter Sheryl Smith  suggested would also be a good idea if space can be found.  The consequences of these plants need to be made more widely available to people who generally rely on "expert" opinions of sales people to make their purchases or the suggestions of friends and family who have been referred to these plants by said "experts". Finding ways to address both the peer pressure/industry standard one size fits all solutions will likely bee needed in addition to taking efforts to raise awareness of the issue, but for a first step this proposed regulatory action is progress.