JoAnne Skelly: Fall is in the air

The calendar says the first day of autumn has arrived, but I’m having trouble believing it. The temperatures are lovely and there hasn’t been a freeze. Last week I was worrying about the way my cucumber and tomato plants looked before I realized that summer gardening was just about over anyway.

Even though my skin says it’s still late summer, fall is here. Did you know that trees and shrubs that are somewhat drought stressed and slowing in growth will do better than those still actively growing as we head into the cold seasons? Hardening off a plant slowly is better than shocking a plant into dormancy with a cold snap. I used to advise backing off on irrigation by the end of August, but with the change in climate, I now advise by the end of September. I am taking my own advice and reducing the water my plants receive. First, however, I will water them deeply and then back off from my daily watering.

When I say drought stressed, I do not mean that plants should be suffering. As the daytime temperatures drop into the low 70s or below, established plants should do fine on a once-a-week deep watering, unless the soil is a heavy clay and stays wet, then watering less often would be appropriate. Deep means to a depth of 12 inches to 15 inches all the way around the plant (specifically trees and large shrubs) out to the dripline at the end of the branches.

Eventually it will be time to shut down irrigation systems, but before shutting them down for winter, be sure to deep water everything. Then, plan on watering once per month throughout the fall and winter, unless we receive an inch of rain for that month or have snow standing on the ground for a week or so.

This is an excellent time to prune maples, birches, beeches, poplars, elms and willows. They are less likely to exude copious amounts of sap through the pruning cuts at this time of year. I plan to fertilize the lawn now with a 16-16-16 fertilizer. This will help roots get strong and set up the lawn for success for next spring. I try to avoid high nitrogen (the first number of the analysis) fertilizers in autumn to avoid stimulating fast growth, which can easily become diseased with the onset of freezing weather.

Wait to prune roses until next spring. Only prune evergreens after hard freezes have sent them into dormancy, otherwise the pruning cuts could attract bark beetles and borers.

Where did summer go?

JoAnne Skelly is Associate Professor & Extension Educator Emerita at the University of Nevada Cooperative Extension. Reach her at skellyj@unr.edu