Weatherman, Weatherman! Look at my Tree!

Many folks believe that plants are good weather prognosticators. They point to various signs such as early (or late) fall color or heavy (or light) flowering and fruiting as an indicator of some future "different-than-normal" weather phenomenon. Actually, the trees, like us, are great at hindsight, not foresight. My mature American elm tree has shown the effects of last fall's strange weather as it has leafed and flowered this spring. It has produced about ten times the normal amount of samaras, the little winged discs that are its seeds. I have been sweeping them up and shoveling them off the sidewalks and patio into heavy duty leaf bags to be hauled away. They blanket every flower bed as if I had mulched with them. You cannot see the soil. The grass has to be raked where they accumulate so that it won't be smothered as it would under falling leaves. I have never seen an elm fruit so heavily.

Looking up into the tree gives me another shock. The branches appear to be clothed in leaves, not bark. The tree has produced so many short leafy twigs along all the branches that you cannot see the bark anywhere above the second major crotch. What's going on here? This is an elm tree that is lovingly cared for and receives its Dutch elm disease preventive regularly.

Well, it's like this...

The winters in zone 4 are predictably cold. The average winter low temperature ranges from -20 to -30 degrees. You would think that planting only plants that can withstand that extreme would give us carefree landscapes. Think again. The amount and timing of the snow cover greatly affects the survivability of many plants, including trees. Another factor is what happens at the beginning and end of the cold period. Those are the critical times that regulate dormancy and the survival of flowering tissue. Last fall, Minneapolis experienced a record breaking warm fall. Most of the trees in town never developed their fall color because the nights never got cold enough to trigger the process. The lowering temperatures usually signal the trees to begin their winter dormancy. Last year, in late October, the first killing frost caught many trees still covered in fully functioning leaves.

When the first snow fell, and was followed by high winds, we were treated to the strange sight of dry, brown leaves blowing around on pristine snow cover. It looked so odd!

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