We have a reasonable collection of Penstemon mainly by taking cutting from our own plants and other gardeners plants over they past 4-5 years. As we know, as beautiful as they are Penstemon are only partly hardy and a heavy winter as 2010 can wipe out much of the collection.
After the effects of that winter, I now take cutting in August of 2-3 of each variety (as a precaution) and when rooted, I transplant into 4 inch pots in October. They are overwintered in our heated conservatory (exept on mild days in November to late February in the cold GH as not to allow them to grow `leggy`).
They are then potted into 5 inch pots until mid May when they are planted in their bedding positions where they flower from mid to late July onwards. My problem is that I finish up with a larger number of plants of similar varieties.
My question is, how do you protect the plants in the beds incase we do have a severe winter coming up? Do you cover the roots with bark chippings or other means?