Why won’t people plant more trees and shrubs in the fall rather than in the spring?
I asked Russ Thompson, who retired after 34 years for the Clark County Parks and Recreation Department, to pass along his reasons. He does horticulture consulting and can be reached at sunkissedhorticulture.com.
“If we thought like trees and shrubs, we’d plant them in the fall. You can expect higher survival rates and healthier plants. I guess too, if it’s too cold for us, it’s too cold to plant trees and shrubs,” he said with a smile.
Thompson listed several reasons why we need to plant more in the fall:
Fall weather conditions are ideal: Las Vegas’ high daytime temperatures run in the high 50s and low 60s through the winter, making it ideal for planting. Spring-planted trees and shrubs start out with two strikes against them. Plants are struggling to produce nutrients to develop twigs and leaves. Then, Thompson said, you throw our summer winds into the equation, and it really can desiccate plants.
Plants will produce a massive root system: Thompson said we always forget about the roots. With our mild climate, plants will be generating roots throughout the entire winter. In fact the plant’s roots pick up a year’s worth of growth to face the upcoming heat wave.
As part of a research project in Oklahoma, the researcher planted lots of pyracanthas in the fall and the next spring to test out the fall planting theory. The following July, he shut off the water of both plantings. In August the spring-planted pyracanthas looked like Custer’s last stand as most were dead. The fall-planted pyracanthas had a 100 percent survival rate.
The fall-planted root system told the real story. They had three times more roots than those planted in the spring to absorb more nutrients for more durable plants.
In a related experiment, spring-planted river birch had extensive twig dieback while fall-planted birch had little dieback. This helps explain why we see dieback in spring-planted trees. Dehydration is the cause as the roots are not able to extract enough water for the new twigs.
An Ohio research study of root growth on roses through the winter found rose roots grew all winter. “If rose roots grew through Ohio’s winters,” Thompson said, “imagine how much root growth you’ll get in Las Vegas.”
Plants won’t require as much water: Those leaves still on the trees are thicker with waxier coatings so you won’t have to water as often and they’re building up food reserves through the winter for next summer’s harsh conditions.
Expect lower prices from garden centers: Nurseries want to reduce their inventory for the winter so they are cutting prices. Also nursery personnel have more time to help you select the right plants for the right places and be able to pass along tips to help you be more successful.
More time available: Haven’t you got enough to do in the spring — pruning, fertilizing and cleaning up? Thompson asked. When people try to accomplish all these tasks in the spring, they become frustrated. Remove these frustrations by planting this fall.
Thompson finds neglect to be a major problem for the death of spring-planted trees and shrubs. Yes, you planted as prescribed, but something may go wrong with the irrigation system and you didn’t catch it and your plants die. We want to blame the nursery, when in reality it’s our fault. Fall plantings will help some to rectify this concern.
In conclusion, Thompson played a major role in changes made within the green industry:
■ He was part of the campaign to stop the topping of trees.
■ He expanded the plant palette in our county parks, with the Chinese tallow being an example. This tree’s leaves change colors in the fall, something Thompson really misses as he is from New York.
■ He helped develop a strong certified arborist program, something we didn’t have in our valley.
■ He and the Southern Nevada Arborist Group are trying to stop the use of sod cutters to remove sod under trees when people convert to desert landscapes. Thompson said, “People don’t realize they are removing most of the tree’s feeder roots and it dies.”
The group recommends killing lawns with an herbicide and then mowing the grass to the ground to save the tree’s feeder roots so it makes it through the transition.
Linn Mills writes a garden column each Sunday. You can reach him at firstname.lastname@example.org or call him at 702-526-1495.