The intense sun of our mountains seems to fade the color in our gardens as summer moves toward fall. With just a little planning, however, local gardeners can enjoy vibrant late summer/autumn color right up through first frost.
Many perennial plants that thrive in our zone 4 environment produce fresh late-season flowers while others sprout bright berries and fiery foliage in the fall. If you plant some fall blooming perennials right away this spring, you just might capture some of that color this fall.
If you're looking for tall blue and purple flowering plants, consider Russian sage (Perovskia atriplicifolis) for August & September color or globe thistle (Echinops ritro 'Tallow Purple'). Medium height purple & blue fall flowering plants include Tatarian statice (Goniolimon tataricum), Tube clematis (clematis heracleifolia), and Plumbago (Ceratostigma plumbaginoides). Short purple & blue fall plants include Beard-tongue (Penstemon campanulatus), Siberian statice (Limonium gmelinii), and Hosta (Hosta sieboldii 'Ginkgo Craig').
For pink color in the fall, consider one of my favorites, a large pink crocus named 'Waterlily.' Japanese anemone (Anemone hupehesis 'Prince Henry') blooms pink in August/September as does Grapeleaf anemone (Anemone tomentosa), sunset hyssop (Agastache rupestris), Joe-pye weed (Eupatorium maculatum), Wild beebalm (Monarda fistulosa), New York Aster (Aster novi-belgii 'Finalist'), Live-forever (Hylotelephium telephium), Showy stonecrop (Hylotelphium spectabile 'Autumn Glory), and Obedient plant (Physostegia virginiana) Consider, too, Sedum 'Autumn Joy' with its pink flowers and mahogany stalks.
Fall flowering plants that provide rich red hue include blanketflower (Galliardia), New York Aster (Aster novi-belgii 'Winston S. Churchhill'), and the second bloom of yarrow (Achillea millefolium 'Red Beauty'), and Cardinal flower (Lobelia cardinalis).
Yellow and orange flowering fall perennials include sunset hyssop (Agastache rupestris), threadleaf coreopsis (C. verticillata 'Moonbeam'), Blanketflower (Gallardia x grandiflora 'goblin') and many mums, asters and sunflowers.
For some cool white flowers in the fall, plant Boltonia (Boltonia asteroids 'Snowbank), Whirling butterflies (Gaura lindheimeri), Aster 'White Fairy' or 'White Opal)' Pearly everlasting (Anaphalis margaritacea)or Giant daisies (Leucanthemella serotina 'Herbstern').
For berries and colored foliage, consider some of these trees and shrubs.
Sumac (Rhus aromatica, R. glabra) with its red-purple and yellow-orange fall foliage gets a bad rap for its poisonous variety, but these two species are safe as well as wonderful to have in your garden. Hedge Cononeaster (Cotoneaster lucidus) offers wonderful fall color and can handle poor soil.
Waxflower (Jamesia Americana), the only native hydrangea in the state, turns red in the fall.
Viburnum in several species offer year-round interest with spring flowers and changing fall colors. Burning Bush (Euonymus alatus), as the name implies, turns a brilliant red in the fall. Redtwig Dogwood (Cornus stolonifera, C. sericea) offers beautiful fall color as well as bright red winter twigs that are a striking contrast against the snow in your winter garden.
Plan for some fall color in your garden and enjoy the season-long beauty of your garden despite the challenges of our high country environment.
Deb Babcock is a Master Gardener through the Colorado State University Cooperative Extension office in Routt County. She thanks the Department of Horticulture and Landscape Architecture at CSU for their research into perennials for the high mountains. Questions? Call 879-0825 or email: firstname.lastname@example.org