Many folks are surprised to learn that autumn runs a close second to spring as an ideal planting time, but it’s true: cool temperatures, reliable rainfall, and short, bright days help plants make a quick and easy transition to your landscape. Despite the cold weather lurking around the corner, the entire first half of autumn (and then some) provides ample opportunity for plants to grow roots and get off to a good start in their new home.
You can plant up to 6 weeks before your ground freezes. Once the ground is frozen, root growth will cease almost entirely until spring, and that six-week window gives the plant time to get established enough to withstand cold and snow. The date that your ground actually freezes varies from year to year, of course, and some areas won’t have frozen ground at all. If you’re unsure, mid-November is a safe planting deadline for nearly everyone.
Get everything in the ground before the ground freezes. If you still have plants in their nursery pots, get them in the ground before winter, no matter how late it has gotten. The plants will be much happier and better protected in the ground than in their thin plastic pots, so even if it’s getting quite late in the season, just plant them where you can. You can always move them in the spring if you change your mind.
Provide supplemental water when needed. Autumn weather can be quite cool and rainy, but that doesn’t mean that new plantings should be ignored, particularly if the weather has been dry and/or windy. Water all plants thoroughly after planting, and continue to water them as needed until the ground freezes.
Just as you pile on blankets and quilts when the temperatures dip, mulch acts as insulation for plants. Mulch also creates the ideal environment for vigorous root growth, which helps new plantings get off to a good start. While even established plants benefit from a nice layer of mulch, newly planted specimens especially appreciate the protection it offers from the challenges of winter.
Know what to expect
You won’t see much top growth emerge on fall-planted shrubs, but this is actually a good thing: any new growth that the plant produces now will be too soft to survive the impending cold anyway. Autumn planting is all about giving the plant a chance to put on root growth, which continues until temperatures average about 48°F/9°C. Plantings will be raring to go come spring thanks to the roots they create in fall.
Bonus tip: All of these guidelines apply to transplanting as well as new plantings, so if you’ve been considering moving something that’s already a part of your landscape, fall is a great time to do it.