I would think that it would be some perceived environmental hazard that the state of Washington is worried about. Anytime you import a plant from another area you risk bringing in new pests or diseases. Some states are particularly mindful, such as California, Hawaii and apparently Washington. If growers outside the state want to ship plants to Washington for instance, they have to comply with their rules and regulations. It can be costly and time consuming for the growers, so they opt instead to just not ship to that state......Maryl

Check with your state agricultural department.

Here is a link that might be useful: state of WA plant quarantine regulations

Maryl and hoovb, thank you for the responses, w
i was curious as to why.

Thanks again,
Gale

Gale......The reason is that one must be a registered and state inspected nursery to ship to Washington.That is the only way to acquire the required certification label on the shipped package.....Many smaller sellers do not have this status.

Marri

Marri, Thank you, for clearing that up for me. As an individual who's job from Spring through Fall is as a herbicide applicator for the Irrigation District I work for, I know all about invasive plants (Purple Loosestrife is terrible). Thanks to the west side of my state, we are very heavily regulated, but this is one that makes sense.

Thanks again,
Gale