The recent weather is a reminder that autumn is just around the corner. Autumn is a good time for many gardening activities before Old Man Winter arrives and we move many of our activities indoors.
Even though autumn is still a few weeks away, it’s time to get busy with fall planting activities. Until recently, most gardeners thought fall was time to tuck in a few more bulbs and put the garden to bed. But now, fall is recognized as a good time to do nearly everything in the garden.
While fall is well defined by the calendar, the planting period is a season of its own that extends from early September to mid-October. Because planting hardy spring bulbs and renovating perennials works well in this period, it’s logical that woody plants can also be moved or planted. With some exceptions, most can.
The main concern regarding fall planting is that new plants have enough time to establish their roots before soil temperatures cool. Site conditions — available moisture and warm soil temperatures — are among the determining factors.
Mother Nature usually plants in the fall. But she uses tough winter-hardy seeds that survive the cold and germinate the following spring when temperatures are warm. I doubt if she ever considered digging an entire plant in the fall or setting-in an entire container grown plant this time of year. Nevertheless, if you understand what happens to a fall-planted tree or shrub, you can work with nature to provide optimum conditions.
The most important things to do in the fall planting programs are to start early enough for roots to grow and become established and to follow proper planting procedures.
With these in mind, I feel that early September is the best time to plant in this area.
Dig a hole that is larger than the root ball of your plant and use good quality soil as backfill. Give plenty of water to keep the soil moist. Add support stakes to large trees and wrap trunks to reduce moisture and temperature loss. After the soil freezes hopefully in December or January, add a 3- to 4-inch layer of mulch over the root and surrounding area to prevent heaving and root damage.
The plant itself is also a determining factor in its survival. A study done on fall planting determined that the following plants have a high risk of loss and should be planted only in the spring: Hornbem — Carpinus species; Golden Raintree — Koelreuteria; Tulip Tree — Liriodendron; Magnolia — Magnolia species; Scarlet Oak — Quercus coccinea; Burr Oak — Quercus macrocarpa; Willow Oak — Quercus phellos; Red Oak — Quercus rubra; Selkova— Zelkova serrata.
The following are risky. Transplant on freshly dug stock and move plants quickly and carefully. These should be staked, wrapped and given extra care during fall planting: Red Maple — Acer rubrum; Birch-Betula species, Flowering Dogwood — Cornus florida; Hawthorn — Crataequs species; Bradford Pear — Pryus calleryana; Silver Linden — Tilia tomentosa.
However this group should survive fall planting if you place them in early September and give them adequate care: Winter Barberry — Berberis julianae; Engish Ivy — Hedera helix; Japanese Black Pine- Pinus thunbergii; Japanese Holly-Ilex crenata; Rhododendron — Rhododendron species; Hemlock — Tsuga canadensis; Leatherleaf Viburnum — Viburnum rhytidoophyllum.
Fall-planted container grown plants generally have a better survival rate than balled and burlapped ones, but I would still hold off planting high-risk plants until spring.
As you can see, autumn is a busy time the year for gardeners.
Bill Lamont is a professor emeritus of vegetable crops in the department of plant science at Penn State and can be reached by e-mail at firstname.lastname@example.org.