Many across CNY may be getting that itch, especially coming out of the pandemic, to get out and start planting flowers, but with this chill lately, you might want to hold off a bit longer. While the odds of frost are going down, Syracuse still can get frost this time of year.
The average last date when the temperature dips to the freezing mark (32°) in Syracuse is April 29th. So one might think that after April 29th it’s safe to plant sensitive plants/flowers since you need the temperature to reach 32° for frost to develop, right?
Think again. Since the temperature is measured about 6 feet up off the ground it doesn’t always reflect what the temperature is at ground level. When conditions are good for radiational cooling (clearer sky, light winds) the temperature is often a bit colder at ground level due to the colder air being more dense and therefore it sinks as low as it can go. Bottom line, you can still get some frost to develop on the ground at 34 or 35, and even 36°. The diagram below shows just that…
If you are thinking about planting sensitive plants late this week/weekend when the current stretch of cool/chilly weather ends, be sure to keep a close eye on the forecast lows through much of May. If lows are expected to drop into the mid-30s or lower on any particular night we would highly recommend either covering or bringing them inside.
The earliest last date that the temperature reached freezing was April 9th back in 1955. The latest date that Syracuse recorded a temperature of 32° was May 24th, 1963.
The earliest last date Syracuse recorded a low less than or equal to 36° was back April 19th, 1916, while the latest date to have a temperature that low was back on June 5th, 1964.
Of course, we all remember Mother Day’s back in 1996 when Syracuse had over 2 inches of snow. Usually, the rule of thumb is to wait to plant the more sensitive plants and flowers Memorial Day weekend, or between the third and fourth weekend of May. So if you are going to plant before then be sure to pay close attention to the forecast lows.