Warming Up, Bad or Good?

I think the most common question that I am asked in February, when the inevitable slight warm stretch arrives, is “Are you worried about any damage to the plants at Wellfield?” Each year is different. The most important thing to remember is that, if you have selected plants appropriate for your area, most of these plants have adapted to the conditions of our growing zone over long periods of time. This is not their first rodeo. Many plants use a complex set of fail checks against leafing or flowering out at the wrong time. The precise way plants determine when to leaf or flower is not completely understood, but it appears that they rely on tracking day length, temperature and humidity to know when to start active, visible growth. If one of those environmental factors, such as temperature, is out of the norm it does not necessarily change their “schedule.”

At this time I do not think the plants in the various gardens at Wellfield have exposed enough plant tissue for irrevocable damage. A single night with lows dipping just below freezing are not necessarily a concern. It all depends for how long the temperature lingers at those temperatures. It is important to note that much of the night time hours are spent above the predicted low, well out of the danger zone. Wellfield is also a very open flat sight with good air currents. Frost does not form easily in such conditions. Low, sheltered locations are in greater danger as the air is still long enough for moisture to settle and form ice.

There are two forecasts that I watch each spring and fall: the ten and thirty day forecasts. I watch to see if the ten day forecast highs and lows are within the window created by the averages for monthly high/low trends. I adjust my seasonal plans based on the 10 day trends. Is the trend significantly higher or lower compared to normal averages? This tells me if I need to take drastic action such as lightly mulching or floating row covers. By in large, I do nothing and work with what nature decides to serve up for the season.

This post starts an ongoing series of horticulture tips written by Wellfield Horticulture Manager, Josh Steffen.