by High Country Gardens

Xeriscape garden in September.
A colorful low-water garden in September, featuring Hummingbird Mint (Agastache), Perennial Sunflower (Helianthus) and Russian Sage (Perovskia)

Why Fall Is An Ideal Time to Plant

September and October is an excellent time to transplant perennials, shrubs and trees, particularly in the Southwest, where winters are mild and the summers are extremely hot. Although you won't see a lot of stem and leaf growth in the fall, the plants are busy growing new roots. With the arrival of spring, the fall-planted garden is ready to burst forth with vigorous new growth and a profusion of flowers.

Berberis Fendleri'Hardy, broadleaf evergreen shrubs, like Berberis fendleri, are great for fall planting.

Fall Planting: Growing Strong Roots

80% of a plant's root growth occurs in the late summer and fall months. Root growth continues slowly through the late fall and winter, as long as the soil is not frozen. Better root growth increases the number of nutrients stored in the plant over the winter.

Compared to spring-planted perennials, which suffer a period of transplant shock, plants installed in the fall grow rapidly in the spring—with both substantial root growth, and more vigorous top growth and flowering.

With a more established root system, fall-planted trees, shrubs, and perennials are much better able to handle the harsh, drying winds of spring and the withering heat of summer.

Fall Planting For Waterwise Gardening

Fall planting is better from a water-use perspective:

  • As plants begin to go dormant in the fall, they use less water.
  • The soil is cooler in the fall, so it stores moisture better.
  • Watering is easier, because you have to water less frequently.
  • Fall is less windy than spring. Wind dries out the soil quicker and dehydrates plants.

However, water is crucial during the fall and winter. Water regularly through the fall months, decreasing frequency as the daytime temperatures cool in late October and November. From 2-4 weeks after planting, the plant should be rooted, especially if Superthrive root stimulator is used at the time of planting.

Once a plant is established, watering frequency can be reduced. When the soil begins to freeze, soak it once every 2-3 weeks through the winter months, except when it is very cold and the ground is frozen solid.

Mulching is also essential to successful fall planting. It keeps the plants from drying out in the dry fall and winter weather, and will keep the soil frozen over the spring months to prevent frost heaving of the roots.

Recommended Plants for Fall Planting:

Hardy deciduous trees, shrubs, vines, and perennials.

  • All narrow leaf evergreens and broadleaf evergreen shrubs in Zone 5 and under.
  • Pansies and shrub roses are excellent for fall planting.
  • Tulips, allium, crocus, daffodils and all spring-blooming bulbs.

With the arrival of spring, the fall-planted garden is ready to burst forth with vigorous new growth and a profusion of flowers.

Exceptions to fall planting:

Plants that are borderline in hardiness should not be planted in the fall (late August to mid-October). In Santa Fe, trees and shrubs that are better planted in spring would be:

  • Rose of Sharon
  • Crepe myrtle
  • Photinia
  • Nandina
  • Mahonia
  • Hybrid Roses
  • Mimosa
  • Japanese Pagoda
  • Ginko biloba
  • Birches

Perennials to avoid planting in the fall are:

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