Events & Resources...

This is not an exhaustive list but it'll get you started...

Perennials/Groundcovers:
Amsonia hubrechtii

Heuchera hybrids

Hosta hybrids

Tricytis formosana

Rodgersia

Helleborus

Lobelia 'Ruby Slippers'

Lobelia vedrariensis

Chrysanthemum 'Sheffield Pink'

Rudbeckia fulgida var. Fulgida

Panicum hybrids

Calamagrostis hybrids

Geranium hybrids (Bevans, Ingwerson's, Rozanne, Blue Azure etc...)

Ferns – Athyrium, Dryopteris

Ligularia 'Othello'

Brunnera macrophylla

Epimedium hybrids

Carex 'Ice Dance'

Nepeta 'Blue Wonder'

Trees/Shrubs:

Fothergilla

Spirea 'Snowstorm'

Spirea 'Blue Kazoo'

Buxus species and hybrids

Buddleia hybrids

Hamamelis

Heptacodium

Syringa dwarf hybrids

Hydrangea quercifolia

Caryopteris

Physocarpus 'Summer Wine'

Viburnum 'Summer Snowflake'
Viburnum nudum hybrids

Cornus mas

Stewartia pseudocamelia

Styrax japonica

Prunus Okame

Prunus autumnalis

Weigela 'Wine and Roses'
Itea virginica hybrids

Thuja plicata, Thuja x 'Green Giant'