TheGardenLady received this question about planting and transplanting perennials, in particular hostas:
I live in southern Alberta. Can I move perennial plants now (sept 18)? I would also like to move some hostas.
The Fall is the best time to plant or transplant many perennials. You can plant or transplant plants up to 6 weeks before the first killing frost is expected in your area. Generally the Fall is the best time to transplant trees, shrubs and perennials and you have the added bonus of being able to buy plants on sale at this time of year. A Fall planting guide for Canada is this.
Hostas are forgiving plants and can be planted any time of the year when the ground is not frozen. Most books say that the best time to plant or replant Hostas is in the spring as soon as the soil is workable. This spring planting is for your benefit. Hostas like moisture, so if you plant or transplant them in the spring you have nature doing the watering for you. However, that being said, in Alberta, Canada you can plant Hostas now if the ground is still workable and if you are not getting a frost for 6 weeks – Hostas and other perennials need that time for the roots to get established. Just be sure that you plant your hostas in well draining soil where there is a lot of moisture so that the roots do not dry out.