Ask Mr. Smarty Plants

Wow! All the way from England. Nice Olympics, by the way. As it happens, your question is a little out of our territory. The Lady Bird Johnson Wildflower Center, home of Mr. Smarty Plants, in Austin TX is dedicated to the growth, propagation and propagation of plants native not only to North America but to the area in which those plants grow naturally. However, we have a previous answer in which the gardener confused Penstemon cobaea (Wild foxglove) and/or Penstemon digitalis (Mississippi penstemon) with the actual Digitalis Purpurea, native to Europe but not to the United States.

Please read the previous answer we have linked you to, which says, among other things, that the real foxglove may be capable of taking toxins up that are already in the soil but not of injecting any toxins into the soil. If you suspect toxins in your soil you need to find the horticultural or agricultural department of a local university and find out how you can get your soil tested. In Texas, this is usually accomplished by the County Agent of the Extenstion Service of Texas Agricultural and Mechanical University, if that gives you a clue on where to start looking. The college in your area would be the best equipped to advise you whether you can detoxify your soil if it is toxic, or not to worry about it.

Here is an article from North Carolina State University on Digitalis Purpurea. This does advise of the poisonous charcteristics but does not mention toxicity in the soil.