Why do we plant in the fall? Back in the days before nursery plant production converted to container production, all tree planting took place in the fall. This is because trees were bare rooted out of the ground, had their roots pruned, and were mudded back into their new home. Things have come a long way since then, but fall is still the best time to plant most species of plants.
The exception to this rule of thumb is broadleaved evergreens, such as hollies and boxwoods. These plants are much more susceptible to winter desiccation from cold, drying winds when the soil is frozen, preventing water to be taken up. Coniferous evergreens generally fare better than broadleaves because of the smaller “leaf” surface, but care should be taken to assure they get a thorough soaking before that last big freeze happens.
Deciduous trees and shrubs are great for fall planting because their leaves have fallen off naturally, allowing the plant to shift its body chemistry to a dormant state. The foliage is not wicking away valuable moisture, and the root system gets tucked away for winter beneath insulating soil and mulch.
Herbaceous perennials like coreopsis, monarda, and salvia benefit greatly by being planted in the fall. One-gallon perennials can be planted right up until the ground freezes if they are watered in and mulched. In our area, smaller containers like pints and quarts shouldn’t be planted past the first week of November. They can be subject to frost heaving and end up freeze-drying after losing contact with the insulating soil. Smaller plants like plugs, 606’s, and elle pots should not be planted after October 1. There is just not enough time for them to become well-rooted before freezing temperatures arrive.
Besides the ease of not having to monitor moisture levels of new plantings, the other big advantage to fall planting is the time factor of roots being in the ground. They will start growing after planting and have a huge head start in the spring, being able to resume their growth as soon as temperatures allow. In my years of working around nurseries and planting operations, I’ve seen fall dug trees pulled out of holding areas in the spring with 6-10” of new roots!
The most important thing to remember is to water new plantings well before the onset of real winter weather. If we have 3-4 weeks without precipitation and warmer temperatures during the winter, invest in your new plantings by giving them a much-needed winter drink.