Plant Exchange Blog

If we were at coffee in Garrison Keillor’s Chatterbox Café, and someone showed you a photo of a lilac blooming later this fall, would you say it’s an indicator?

Days have been outrageously pleasant. We had a killing frost a month late and mostly mild days since in this region. What about unusual plant responses What about this lilac in bloom?

Blooming heirloom lilacs are a harbinger of spring. Their responses are so predictable an indicator that botanists select lilacs for phenology studies of plant response to seasonal changes across the United States.

Nurseryman Jay Gurney, who will celebrate 40 years at Yankton Nurseries in 2017, keeps an eye out for weather and plant indicators.

“’Bloomerang’ Lilacs, by Proven Winners, are a re-blooming lilac in August or September. Or sometimes a Dwarf Korean lilac will re-bloom late,” Gurney said. He doubts the photo blooming lilac we saw is the old fashioned kind.

“Roses bloom until a hard frost. A viburnum will sometimes have a late tip bloom. Is this a lilac in an unusual spot, such as up by the house?” He has lilacs that have mostly lost their leaves as expected for this time of year. He hasn’t heard other comments about lilacs blooming now, and he gets quite a few questions from people around the region. He’d like to see such a blooming plant.

At the Chatterbox, we are reveling in the unseasonable warm days. But there’s a gnawing implication of some ‘heck’ to pay’ for our good fortune as we motion for coffee refills. So we press Gurney for information. What will this nice weather do to plants?

“Generally, it doesn’t hurt them at all; they’re not being punished by brutal weather,” he said.

“But in the early 1990’s, we had the ‘Halloween blizzard,’” he said. “Weather was warm and dry like now. Then before Halloween we had two or so inches of rain. On the backside, it turned into a blizzard. Super cold. That was hard on plants; they didn’t have time to harden up.” Abrupt weather change is a challenge to plants.

“But what I’m seeing now is tree leaves falling naturally as days shorten. I don’t see trees growing. Willows grow later and sometimes their wood doesn’t harden up as fast for sub-zero weather. But this year we are having 50 or 60-degree F. days and cool nights, some with light frost.

This Rudbekia or Black-eyed Susan escaped a pot and it is blooming in-ground outside by one of Jay Gurney’s greenhouses. Surrounding this November blooming plant, potted rudbekia perennials are dormant because soil temperature in pots is cooler than in-ground. Shorter day length and dropping soil temperatures are some plant cues for dormancy. Gurney’s potted roses still have leaves and blooms in later November.

“Ground usually freezes somewhere in mid – December. Last winter was a solid USDA Zone 5 winter and some Zone 6 plants survived.” He accidentally left some gladiolas and cannas in the ground last winter and they bloomed this summer. “Ground hardly froze but it didn’t seem to hurt plants–So long as we don’t have a big blizzard that comes so fast nothing has a chance!

“I haven’t seen many geese yet this fall. Once you see them moving south, cold weather’s coming. Soil temperatures and day length play together. Our trees have been around for millions of years. They know what to do,” Gurney said. But a few people just want to do something with this unusually warm weather.

“It couldn’t hurt to soak the yard before you put the hose away,” Gurney said. He includes lawn, trees, shrubs and perennials. “If it stays dry the next six months, you can’t water frozen ground.” Plant a tree or shrub and water them in until the ground freezes. Then they’re in tune to grow next spring. Spread organic fertilizer such as compost or dried manure. One can kill weeds that are still growing. Gurney has been harvesting late season kale, cabbage and broccoli.

For other plant-related options in warm fall weather, Fox Run Golf course is open to enjoy the turf until day temperatures dip below 40 degrees F. or it snows. Lewis & Clark Recreation Area camping is mostly open to experience the change of tree and native grass color and their trails are ready for biking, walking and picnics. Meridian Bridge is open to see Yankton from among cottonwood trees. Warm weather is a free gift without strings!

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