Lawn and garden lessons we learned from the hot, dry summer of 2021
In today's "Growing Together" column, Don Kinzler offers some observations that can help in future growing seasons.
Did you hear about the guy who can’t decide whether to buy new lawn chairs? He’s sitting on the fence.
No matter where you were sitting this summer, it wasn’t very pleasant to be outdoors. Although drought-parched mosquitos were few and far between, the unrelenting heat made much of the summer uncomfortable.
There are lessons to be learned from the growing season of 2021. The severe drought captured more headlines, but the extended heat also affected plants.
The following are observations that can help in future growing seasons.
It’s well-known that Kentucky bluegrass goes temporarily dormant when moisture is scarce, but it’s also known that it can’t remain dormant forever. There’s a point of no return at which grass plants regress from dormancy to death.
To keep dormant grass plants hydrated to prevent death, about a quarter inch of moisture is needed every four weeks or so, depending on soil type. That amount won’t bring the grass out of dormancy and turn it green, but it’ll at least keep the roots and crown hydrated and alive.
Most dormant lawns in the region made an amazing resurrection from dormancy once moisture and cooler temperatures arrived in late August. Small, infrequent sips of rain were all that many areas received during summer, but they were sufficient to keep dormant grass alive until generous rain spurred new green growth.
Not all grass survived. Many lawns had patches that failed to revive and instead lay dead and matted, probably because heat coupled with drought pushed the grass over the brink.
If dead or thin areas weren’t reseeded before mid-September, they can be dormant seeded right before the onset of winter snow. Damaged areas can also be reseeded in spring.
If grass was thinned by drought, Kentucky bluegrass lawns can self-heal if there’s a grass plant at least every 2 inches, because of the grass’s ability to spread laterally by underground rhizomes.
Lawns will continue recovering next year if we fertilize around Memorial Day and Labor Day, allow clippings to filter back into the lawn when mowing, mow at a height of 3 inches, and water deeply and less often.
Weeds, which by their nature are deeply rooted and aggressive, took advantage of grass’s misfortune and spread quickly in lawns thinned by drought. Weed control will be important next May and again in September.
Some well-watered lawns, especially those of sodded origins, suffered brown patches with deteriorating roots. These were likely caused by fungus diseases that thrived in the hot, moist conditions of an irrigated lawn.
Lack of rain certainly diminished garden growth, and watering seldom seems as effective as a good rain.
Heat had nearly as much impact on vegetables as drought. Even warm-loving crops like tomatoes, beans, squash, cucumbers and pumpkins have an upper temperature threshold above which growth and other processes shut down. When temperatures surpass the mid-to-upper 80 degree point for extended periods, even heat-loving plants regress.
Extended heat favored the formation of male blossoms on cucumbers, squash and pumpkins at the expense of female blossoms, without which no little fruits are formed. When temperatures finally moderated, female blossom production resumed.
The ripening of green tomatoes was slowed in midseason’s heat. Ripening is a plant cell process, and plants shut down such processes in extreme heat as an energy saving mechanism.
Pollen is easily injured when temperatures soar, and pollinating bees are less active.
Crops that prefer cool temperatures quickly fizzled in the early summer heat, such as lettuce, spinach, peas and radish.
Heat causes many vegetables to become bitter. Luckily cool fall weather helped crops like carrots become sweeter with increased sugar buildup.
Flowers and shrubs
Blossoms didn’t last long on perennials. They opened quickly and faded rapidly.
Geraniums, which prefer cool weather, sulked in the season’s heat, and didn’t begin decent growth until temperatures cooled in late summer.
Shrubs that prefer cool, moist conditions languished. Many hydrangeas developed yellowed leaves and flower color that was less clear or vivid, becoming muddier because of heat.
The width of an annual growth ring within a tree trunk is an indication of how well a tree grew during the season. When a tree is cut down, the rings show a historical record of each year’s growth. Eventually, when current trees are felled, someone will likely point out the very narrow growth ring that indicates the drought of 2021.
Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at firstname.lastname@example.org.