I’ve been growing ‘Honorine Jobert’ in part sun in a sheltered spot for ten years in downtown Toronto. They came back every spring–sturdy and 4 feet tall! Then the entire patch (about 5 plants) didn’t make it through the winter. I’ve been stubbornly replanting, but for three years they haven’t made it through the winter. Drainage is good. Soil is alkaline and loamy. Should I mulch over winter?
Gosh – I feel your pain. Japanese Anemones, especially your variety; Honorine Jobert are truly one of the most graceful and delicate stars of the late summer garden. Let’s look at some possible issues that may be preventing your plants from thriving:
Light – have overhead trees and branches created more shade than what you once had? These plants do well in light shade, but don’t take well to full shade. Similarly if you have more sun than before, you will have to provide more moisture and definitely mulch.
Moisture – These plants are fussy around watering. They do prefer moist soil – are not at all drought tolerant, but neither can they tolerate soggy soil. Getting the right amount of moisture is important, especially in the early days of planting, they are slow starters, they do take a while to establish themselves and care must be taken during this time as to not overwater or underwater.
Soil – These are fairly heavy feeders, so have you been supplementing your area with fresh humus rich soil? A topdressing of compost in the spring is a great way to keep them growing vigorously.
Pests – Japanese beetles are a big problem and can totally defoliate a plant in no-time. However I think you would have probably noticed if this was the case.
Mulch – to your question regarding Mulching – Definitely ! – this will keep plants cool and moist over the summer and will provide winter protection. I hope this turns out to be your ‘magic bullet’ I certainly encourage to give these beauties another try. Good luck with it!