Friday, September 18, 2009

Groundcovers for Shade

 Dicentra formosa April 2009

 Achlys triphylla May 2009

Oxalis oregana April 2009

Here is a list of groundcovers  that grow in shade for garden in Seattle, the Pacific Northwest & USDA Zone 8.  Generally, groundcovers are perennials that spread over the ground by one means or another. Groundcovers are very helpful to control weeds. They give depth & richness to a garden. They make plantings look more natural. Choose several groundcovers if your garden is small, many if your garden is large. A single groundcover will spread throughout, looking a bit weedy. As in business, it is better to give groundcovers competition than to let them monopolize your garden. You will also get better coverage & weed-suppression by using a variety of groundcovers.  The groundcovers pictured above are all Pacific Northwest native plants.  Many sources of information will tell you they require moist shade.  But these will all survive the summer with very little irrigation.  I've seen Achlys triphylla growing luxuriantly in dry Ponderosa Pine forest on the eastern slopes of the Cascade Mountains.  Although they grow in shade, do not use Hedera helix (English Ivy) or Euphorbia amygdaloides robbiae (Mrs. Robb’s Bonnet). They are too aggressive, will overwhelm other plants & grow out of control. English Ivy is considered a noxious weed by the State of Washington.

Groundcovers for Shade
Achlys triphylla (Vanilla Leaf): tolerates dryness,spreads widely, but not densely by rhizomes
Ajuga reptans (Carpet Bugle): tolerates some dryness, many cultivars, spreads by stolons & seed, also grows in sun
Alchemilla mollis (Lady’s Mantle): tolerates dryness, forms large clumps
Asarum caudatum (Wild Ginger): needs moisture, spreads by rhizomes, but not quickly
Blechnum penna-marina (Sea Plume): needs moisture, forms mats
Campanula poscharskyana (Serbian Bellflower): tolerates dryness, trails & spreads by seed
Dicentra formosa (Native Bleeding Heart): spreads widely by creeping & by seed
Fragaria vesca (Woodland Strawberry): tolerates dryness, spreads widely by runners but will share space, tasty fruits, also grows in sun
Galium odoratum (Sweet Woodruff): tolerates dryness but better with moisture, can spread widely  
Gaultheria nummularioides (Gaultheria): forms mats, needs moisture, Gaultheria procumbens (Wintergreen): spreads modestly, needs moisture
Geranium himalayense (Himalayan Cranesbill): forms spreading mats, not aggressive
Gymnocarpium dryopteris (Oak Fern): needs moisture, forms small spreading mats
Lamium maculatum 'Beacon Silver' (Dead Nettle): despite the ugly common name, a beautiful plant, forms creeping mats with limited seeding
Liriope spicata (Creeping Lily Turf): spreads widely & densely by rhizomes, will overpower other groundcovers & perennials, use under shrubs or in contained spaces
Maianthemum dilatatum (False Lily of the Valley): tolerates some dryness, spreads by rhizomes to form large patches, but will mix with other perennials
Ophiopogon planiscapus 'Nigrescens' (Black Mondo Grass): not a grass, needs moisture, spreads modestly by stolons
Oxalis oregana (Redwood Sorrel): tolerates some dryness, spreads very widely by rhizomes but willing to share space, not difficult to remove
Pachysandra terminalis: needs moisture
Phlox divaricata, Phlox stolonifera (Creeping Phlox): forms mats, needs moisture
Pleioblastus fortunei 'Variegatus' (Dwarf Whitestripe Bamboo) Pleioblastus viridistriatus (Dwarf Greenstripe Bamboo): spreads aggressively, keep in enclosed area
Polypodium glycyrrhiza (Licorice Fern): forms slowly spreading mats, also grows in trees
Sanguinaria canadensis (Bloodroot): tolerates some dryness, spreads slowly by rhizomes
Sedum forsterianum (Forster's Stonecrop): for light shade, spreads slowly
Smilacina stellata (Starry False Solomon's Seal): tolerates some dryness, spreads by rhizome to form large patches, but will mix with other perennials
Soleirolia soleirolii (Baby’s Tears): needs moisture
Tellima grandiflora (Fringecup)
Vinca minor (Dwarf Periwinkle): spreads aggressively by creeping & rooting stems, not for small gardens

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