Fall is the best time to plant trees, shrubs, and perennials in central North Carolina. That may seem counterintuitive, especially if you’re recently transplanted yourself from parts farther north. But our long, relatively warm autumns provide the ideal circumstances for plants to get established.
The Triangle region doesn’t experience the “frost heaves” that northern gardens do. Though the air may be growing cooler, the soil retains plenty of warmth, allowing extensive root growth that gives plants greater resiliency through the hot summer to come next year. Plants designated for USDA Horticultural Zones 6-8, set in a well-prepared site, will survive all but the most harsh winters just fine.
What constitutes a well-prepared site? Employ these tips to make sure your plants get off to their best possible start.
Take advantage of a soil test from the North Carolina Cooperative Extension Service. Soil test boxes may be obtained from your local extension office and the report, emailed to you, will explain your soil’s pH level, as well as the organic matter content and the nitrogen, phosphorus, and potassium needed to bring your soil up to optimum conditions. Soil analysis is available free between April and November, and costs $4 per sample at other times.
Consider the drainage of your site, and add plants well suited to those conditions. You can mitigate drainage problems by adding compost, but a better solution is to plant something that will thrive in the conditions you already have. If a spot tends to collect water, look for plants that like it permanently moist or even wet. By contrast, if you have a spot that tends to stay hot and dry, choose a plant that originates from a locale with similar conditions, like the Mediterranean. Your plants will be happier if they’re not struggling to adapt to their conditions, and you’ll be happier not watching your plants die a slow, ugly death as you contemplate the money you’ve wasted.
Dig good holes. Dig the hole twice to three times as wide, but only as deep as the depth of the pot containing the plant. Don’t loosen the soil at the bottom of the planting hole, and don’t add gravel to improve drainage. Keep the excavated soil to backfill around the plant.
Evaluate the root system critically. Slip the plant out of its pot. If you don’t spill any soil in the process, or if you see roots growing in a circular pattern, your plant is rootbound. If you can’t pull the roots apart, use a pruning saw or an old kitchen knife to saw through the rootball from the soil surface down, cutting the rootball into a square or box shape. After pruning, remove all the soil that came in the container. Rinse the roots off with a quick dunk in a bucket or shoot the garden hose on them. You’ll be able to see and correct any problems that tangled mass of roots may hide.
Although this approach may seem draconian, Dr. Linda Chalker-Scott, professor of horticulture at Washington State University, writes, “Roots that are pruned at transplant time, especially those that are excessively long or misshapen, will respond by generating new, flexible roots that help them establish in the landscape.”
Spread the roots out in the extra-wide hole you’ve prepared, fanning them in all directions. Backfill with the excavated soil, but don’t add fertilizers or other soil amendments in the planting hole. The goal is to acclimate the new roots to the existing soil conditions. Any amendments directed by the soil test can be added as a top-dressing and watered in. Don’t step on the newly-filled hole, but water it to allow the soil to settle.
Avoid mulch volcanoes. Mulching conserves water and minimizes wide temperature fluctuations that can stress new plantings. A three-inch layer of mulch (roughly the length of an adult’s index finger) over the planting site, and pulled slightly away from the trunks of trees and shrubs, is all you need. Anything deeper may encourage at least one of three undesirable circumstances: (1) roots may grow into the top layers of mulch, where they’ll be subjected to stress, instead of into the soil; (2) voles and other rodents may bed down in the mulch and nibble away at your new plantings; (3) the mulch may hold excessive moisture and rot your plant.
Follow these guidelines as you prepare your fall garden, and you’ll be delighted with the results come spring.
Amy Hill served for ten years as an Extension Master Gardener Volunteer for Durham County. She now blogs about gardening at MissingHenryMitchell.com.