Rocky Mountain Gardening: Fall Planting and Seasonal Tasks

Deer- and Rodent-Proof Bulbs

Tired of wildlife eating your bulbs? Try these resistant varieties: Spanish bluebells (Hyacinthoides hispanica), English bluebells (H. non-scripta), daffodils, crimson drumsticks (Allium sphaerocephalum), giant snowdrop (Galanthus elwesii), grape hyacinth, meadow saffron (Colchicum), snowflake (Leucojum), and 'Spring Beauty' squill.

Fall Planting in Zones 2a–3b

Autumn is ideal for planting hardy groundcovers, perennials, shrubs, trees, and vines. Plant at least six weeks before the ground freezes (consult your county extension for timing). Water well at planting and every two weeks through winter. Apply a 6-inch mulch layer (hay, pine needles, shredded cedar, or straw) over rootballs to prevent frost heaving.

Low-Water Irises for Rock Gardens

Small, drought-tolerant irises bloom early in late winter and go dormant by June. Plant at least 100 for impact. Varieties that spread in well-drained soil: yellow Iris bucharica and I. danfordiae; purple I. histrioides 'George'; and I. reticulata cultivars 'Cantab', 'Harmony', 'J.S. Dijt', 'Natasha', and 'Pixie'.

Trees for Fall Interest

For showy fruit: crabapple, hawthorn, mountain ash, spindle tree (Euonymus europaeus), sumac. For red autumn foliage: purple-leaf chokecherry, Gambel oak (Quercus gambelii), purple-leaf plum, smoke tree, Wasatch maple.

Winter Bird Care

Clean birdhouses with 1:10 bleach solution; remount for winter shelter. Keep feeders full and wash weekly. Rinse and refill birdbaths daily.

Flower Bed Cleanup

Remove seed heads from diseased or overly aggressive plants. Leave others for winter interest, crown protection, and bird food. Apply balanced granular fertilizer, water thoroughly, and top-dress with 2–3 inches of compost or well-rotted manure. After the first hard freeze (20°F or below), apply 6 inches of mulch.

Fall Fertilizing

When trees drop leaves or after light frost, broadcast all-purpose fertilizer on lawns, around perennials, and under shrubs and trees. Follow label rates.

Plant Spotlight: Sambucus nigra 'Black Lace'

This elegant elderberry cousin features deeply cut violet-black foliage and pale pink flower clusters in early summer, followed by shiny black berries. Grows 6–8 feet tall, hardy to –30°F. A graceful, hardy alternative to Japanese maple. Plant before winter in Sunset zones 2, 3, or 10. Mulch 3 inches and water monthly through winter.