November 2000 Planting Trial

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In early November of 2000 we undertook a trial planting of perennials in the field. We were hoping to demonstrate that you could successfully plant perennial gardens late into the season. We have been overwintering plants under insulating covers for years with reasonable success,if you discount failures from having been devoured by voles, so we thought why wouldn't they do just as well in the ground. Our nursery is in the Champlain Valley of Vermont - locally considered Vermont's 'banana belt'. We have had -30 degrees F. once or twice but most years it's milder. Having not much time to plan this trial I went through the nursery and grabbed plants that a landscaper might who was needing to make a planting that would have a sequence of interest throughout the season. I also chose plants for different light requirements. I think I was also limiting the palette to plants that we consider widely used. These are all plants that have been long-lived in our gardens. One each of the following were planted in the field on November 3, 2000. The plants were mulched with approximately 2" of shredded bark mulch, and watered in.

ALCHEMILLA mollis 'Auslese'
ARMERIA m. 'Bloodstone'
ARTEMISIA schmidtiana 'Nana' [Silver Mound]
ATHYRIUM niponicum 'Pictum'
CIMICIFUGA racemosa
COREOPSIS verticilata 'Moonbeam'
DICENTRA spectabilis
DRYOPTERIS affinis x felix-mas 'Robusta'
ECHINACEA purpurea 'Alba'
ECHINACEA purpurea 'Magnus'
EPIMEDIUM rubrum
FESTUCA 'Elijah Blue'
HEMEROCALLIS 'Stella d' Oro'
HOSTA undulata 'Albomarginata'
IBERIS sempervirens
LAMIUM maculatum 'White Nancy'
LEUCANTHEMUM 'Snowcap'
MISCANTHUS s. 'Silberfeder'
NEPETA faassenii 'Six Hills Giant'
NEPETA sibirica 'Souvenir d' André Chaudron'
NEPETA 'Walker's Low'
OSMUNDA cinnamomea
PEROVSKIA atriplicifolia
PHLOX 'David'
PHLOX 'Emerald Cushion Blue'
RUDBECKIA fulgida 'Goldsturm'
SEDUM 'Herbstfreude' ['Autumn Joy']
VIOLA cucullata 'Purple Showers'

I did an accounting of the planting on September 20, 2001 and found that Perovskia atriplicifolia had died and Nepeta 'Six Hills Giant' and Viola 'Purple Showers' were missing. We assume they died or were eaten by voles (I know... that still counts as dead). I found the label and location for the Viola. I was unable to find either the label or location of the Nepeta. The plants were planted in a row approx. 48" wide and plants were typically three across in the row, hence there should have been an empty slot for the Nepeta. I assume it died, but perhaps it was never planted. All the other plants survived and grew well, considering a fairly severe drought this summer and minimal supplemental irrigation.
I'm certain that this test wouldn't pass muster as scientific evidence, but this is what we did and what we observed. We did have great snow cover the past winter, but my experience over the years leads me to believe that the bark mulch around the plants serves as well as snow in preventing frost heaving which I believe is a critical factor in late season planting success. Certainly the bark mulch does nothing to prevent leaf scorching or the tip die back you might experience with the evergreen perennials or sub-shrubs such as iberis sempervirens or phlox subulata, but those symptoms rarely impact the plant's health or vigor.
This planting had an approximate failure rate of 11%.