It’s true that trees and shrubs planted in the cooler fall months establish themselves better than those planted in spring.
Spring is a time of year when plants are drawing up energy reserves from their roots to flush out leaves, flowers and later, fruits. This process saps reserves for a while since these leaves demand water and nutrients that the roots must source in the soil. Much better for the plant if the roots get several months, over the winter, to establish themselves before they need to supply water and nutrients to the rest of the plant.
If the air temperature is in the mid 40s or above, you can feel confident that it’s a good day for planting. Be extra vigilant to water in your newly planted tree or shrub. Water until you have created a slurry of mud because your goal is to eliminate any air pockets to ensure that the roots are thoroughly covered with soil.
Soil will protect the roots from winter freezes. The soil temperature doesn’t fluctuate as extremely as the air, keeping roots warm in winter and cool in summer. Any air pockets around the roots will be more likely to match the air above ground as it plummets. In summary, roots must touch soil.
This advice is the same for transplanting your existing shrubs or small trees to new locations. Fall is the best time, and you will have better outcomes if the planting is followed by lots of water to eliminate air pockets.
How deep should the dug hole be? Focus more on the width of the hole because shrubs and trees typically have root systems extending beyond their leaves. We call this the drip line because rain drips off the outer most branches and waters the roots. When planting, your aim is to dig 3 times wider than the root ball (or the container.)
Notice where the soil line meets the shrub or tree. The transition between trunk/stem and roots is called the crown. The crown never wants to be below soil or mulch. When planting you need to ensure that the crown will be above the soil line. Adding 2 inches of leaf or wood mulch is a wonderful final step but be sure you don’t let the mulch touch the bark: keep 5 to 6” of free air before the mulch begins.
When everything aligns (right plant, right season, correct size of hole, crown sitting just above soil height, thorough watering, mulching of roots but away from trunk) you will have given your shrub or tree its best shot at a long and happy life.
For questions about which plant or more about how to plant, reach out to NC Cooperative Extension. We are happy to help get you answers.