In last month's High Country Horticulture column, I wrote about various systems which are used to determine where a particular plant will thrive. ( To better understand this month's article, you may want to refer back to the full article entitled Zoning In On Plants For Your High Country Garden which can be found on the Your Hub Website.)

After writing the article, I was asked by several people what I would recommend as the hardiest perennials for our foothills gardens.

Although most of our gardens fall within USDA Hardiness Zones 3 to 5, I began to investigate what plants have a good success rate in gardens which lie above 9,500 or even 10,000 feet. where winter low temperatures can drop below -50°F.

(Take a ride up to Leadville in the summer to see what gardeners who live above 10,000 feet can do.) These gardens fall into roughly Zone 1 & 2 of the USDA Zone designations, although there is not an exact correlation between elevation and zone; and, like all gardens, very high elevation gardens contain a variety of microclimates.

The following list contains my suggestions for extra hardy perennials. They are grouped by sun/shade preference, although several will do well in either setting. Most require low water after established. Generally, however, the shade-loving plants on this list require more water.

ZONE 1 - 10,000 feet

Sun to Part Sun:
Arctic Phlox (Phlox borealis)
Alpine Poppy (Papaver alpinum)
Arctic Campion (Lychnis alpina)
Cut Leaf Daisy (Erigeron compositus)
Harebell (Campanula rotundifolia)
Penstemon, Pygmy Purple (Penstemon hirutus)
Penstemon, Smooth (Penstemon glaber allpinus)
Pink Pussytoes (Antennaria dioica 'Rubra')
Rocky Mountain Primrose (Primula parryi)
Silver Mound Artemisia (Artemisia schmidtiana)
Snow in Summer (Cerastium tomentosum)
Yarrow, Double (Achillea ptarmica 'Ballerina')
Yarrow, Native (Achillea millefolium)

Part Shade to Shade:
Bunchberry (Cornus canadensis)
Columbine, Dwarf White (Aquilegia flabellata 'Cameo White')
Columbine, Rocky Mountain (Aquilegia caerulea)
Lily of the Valley (Convallaria)
Snow on the Mountain (Aegopodium podagraria)

ZONE 2 - 9,500 Feet

Sun to Part Sun:

Basket of Gold (Aurinia saxatillis)
Carpet Bugle (Ajuga reptans)
Columbine, Crimson Star (Aquilegia 'Crimson Star')
Creeping Colorado Holly (Mahonia repens)
Daylily (Hemerocallis, several varieties)
False Rockcress (Aubrieta deltoides)
Grape Hyacinth (Muscari armeniacum)
Himalayan Poppy (Meconopsis sp.)
Hen & Chicks (Jovibarba 'Emerald Spring)
Hen & Chicks (Sempervivum, several varieties)
Hollyhock (Alcea rosea)
Obedient Plant (Physotegia virginiana)
Oriental Poppy (Papaver orientale)
Pearly Everlasting (Anaphalis margaritacea)
Pussytoes (Antennaria parvifolia)
Santa Fe Aster (Machaeranthera bigelovii)
Snow-in-Summer( Cerastium tomentosum)
Stonecrop(sedum sp.)
Sweet William (Dianthus barbatus)
Thrift (Phlox subulata)
Windflower (Anemone)

Shade to Part Shade:

Bigroot Cranesbill (Geranium macrorrhizym)
Bleedingheart (Dicentra spectabillis)
Creeping Lamium (Lamium maculatum)
Dwarf Meadowrue (Thallictrum minus adiantifolum)
Kinnikinnick (Archtostaphylos uva-ursi)
Monkshood ( Aconitum napellus)
Siberian bugloss (Brunnera macrophylla)
Yellow Loosestrife (Lysimachia punctata)

This is only a partial listing of the perennials that our highest elevation gardeners may want to try. ( It does not include Zone 1 and 2 hardy shrubs of which there are quite a few. These will be covered in a future article.) For those of us "lowlanders" who garden between 7,000 and 9,500 feet, these extra hardy plants are excellent choices for our gardens as they will be sure to survive our relatively mild -35° F winter lows.

Nan Spence gardens at 8,200 ft using plants designated for USDA Zones 1-5.