Spring has arrived. Will the Spring snows hurt my plants? It All Depends on Where You Stand! Literally!

Authors
Published on

Spring has arrived. Will the Spring snows hurt my plants? It All Depends on Where You Stand! Literally!

 

By Thomas deHaas, Aaron Wilson, Tim Brotzman and Mark Shelton

 

The short answer is probably not. The long answer it depends more on cold temperatures than on snow.

Even though the first day of Spring is March 21st, 2023, it is common for us to get late winter and even spring snowfalls. The 5 snowiest Marches on record are, 1993 – 17.7”, 2008 – 17.4”, 1916 – 17.1”, 1899 – 17.0”, and 1977 – 15.0”. These amounts were in Northwest Ohio – Toledo.

https://www.wtol.com/article/weather/climate-friday/climate-change-how-much-does-it-snow-in-march-toledo-ohio/512-38d1304c-b5c6-49cc-be5c-6e967153cbe9

 

Actually, snow is not the problem for plants. In fact, snowfall can help insulate plants from cold temperatures. And there is the problem, the cold.

A plant that experiences warm temperatures in late winter will respond by breaking dormancy and beginning to grow. Temperate related to plants is measured in Growing Degree Days. So, what are Growing Degree Days also referred to as GDD?

Growing Degree Days (GDD) are used to estimate the growth and development of plants and insects during the growing season. The basic concept is that development will only occur if the temperature exceeds some minimum development threshold, or base temperature (TBASE). 

https://mrcc.purdue.edu/gismaps/info/gddinfo.htm#:~:text=Growing%20Degree%20Days%20(GDD)%20are,or%20base%20temperature%20(TBASE).

 

In Ohio, there is a network of weather stations that tract weather and growing degree days:

https://weather.cfaes.osu.edu/gdd/

 

Dr. Aaron Wilson, Agriculture Climate and Field Specialist made the following observations regarding this Winter’s weather:

  • This winter (Dec-Feb) was the 2nd warmest on record for the state of Ohio going back to 1895. The winter of 1931-32 is the only warmest. 
  • For most cities in Ohio, this was their top 3 warmest winters. 
  • Until this recent cool snap, many cities were on pace for the fastest growing degree day accumulation in the last 20s years. Still, central and southern Ohio sites are sitting at their top 3 fastest pace through March 14
    • Columbus 90-95: only outpaced by 2017 and 2016
    • Cincinnati 135-140: only outpaced by 2017 (142)
    • Cleveland: 35-40: outpaced by several years, e.g., 2017 had 83
    • Toledo: 35-40: also outpaced by several years, e.g., 2017 has 84
  • Soils only occasionally froze throughout the state, generally just within the top couple of inches but average daily soil temperatures remained above freezing
  • Winter was close to average precipitation wise, but snowfall ran 10-50% below normal.
  • Cooler than normal temperatures are more than likely for much of the remainder of the month. There will be a few mild days in there as we transition toward spring of course, but generally we should not expect a sustained warmup. 

Aaron always makes a great distinction between weather and climate. Weather is what we see every day. Climate consists of trends we see over long periods of time: years, decades, and centuries. Attached is a video on the distinction between Weather and Climate. It’s from 2019 but the concepts are still valid. See the video below:

https://www.youtube.com/watch?v=Y-NlNXn3Agg

 

But these vary from year to year. For example, an observation by Tim Brotzman, Brotzman Nursery indicated that at the weather station located in Madison Ohio – Zip Code 44057 on March 3rd from the years 2014 to 2023, the following Growing Degree Days occurred:

Year       GDD

2014      2

2015      3

2016      25

2017      65

2018      53

2019      18

2020      14

2021      5

2022      11

2023      23

 

Mark Shelton, Willoway Nursery – Huron shared his numbers for March 3:

 

chart

 

Like the title of this article states: “Will the March snows hurt my plants? It All Depends on Where You Stand! Literally!”

 

In 2015, also referred to as the ‘Polar Vortex’, in Madison, Ohio, we posted 19 nights where the temperature was below Zero degrees Fahrenheit between January 1st and May 15th:

Date

MaxAirTemp

RecordMaxYear

1/10/2015

16.9

-2.1

1/13/2015

18.5

-9.5

1/14/2015

19

-11.6

1/15/2015

31.3

-1.2

1/28/2015

28.7

-4.2

2/5/2015

18.3

-3.6

2/13/2015

20

-10.6

2/14/2015

24.3

-1.5

2/15/2015

1.2

-11.8

2/16/2015

6.1

-19.9

2/17/2015

18.8

-17

2/19/2015

9.5

-16.8

2/20/2015

11.9

-24.4

2/23/2015

13.4

-17.1

2/24/2015

22.6

-17.6

2/27/2015

14.5

-13.4

2/28/2015

29.2

-15.4

3/5/2015

21

-6.7

3/6/2015

25.6

-11.8

 

 

 

https://weather.cfaes.osu.edu/dailyinfo_B.asp

 

Another shocking observation that Tim Brotzman points out, occurred on the same date on consecutive years. On February 20th, 2015, we reached a low temperature of 24.4 below Zero Fahrenheit, and the same day in 2016, we had a high temperature of 67.1 F. This was a 91.5-degree difference on the same date, one year later according to GDD data from the Madison, Ohio weather station. Three years later 2018 on that day, the high was 71, making it a 95.4 degree difference.

 

Tim also notes at his nursery he reached a low of 30 degrees below zero on February 20th, 2015 and a high temperature of 73 degrees F on the same date 3 years later in 2018. That is a difference of 103 degree on the same date, 3 years apart.

 

Mark Shelton, IPM Manager from Willoway Nursery- Huron indicates, “Plants in general are pretty resilient to temperature fluctuations for a short period of time. Once a plant leaf’s out it may require some protection. There is a great diversity in plant species to tolerate low and high temperatures. In the end the plant will let us know.”

 

A great reference book that he uses is:

 

Stress Physiology of Woody Plants

https://www.routledge.com/Stress-Physiology-of-Woody-Plants/Dai/p/book/9781032092775

 

But back to this Spring, what to expect?

The most harmful situation for plants is a series of warm temperatures in the 60’s and 70’s followed by a series of cold nights below freezing. The plants begin to grow and flower as in the case of Star Magnolia, one of the first to flower.

 

star1

 

 

 

 

But if we get a frost after flowers emerge, damage will occur.

 

star2

 

 

 

 

 

When these growing plants encounter freezing temperatures, the flowers freeze and in the case of fruit trees or grape vines, this late frost can damage the buds so severely that no fruit will be produced.

 

This peach tree was in full flower.

 

frost10

 

 

 

 

 

 

This happened last winter in 2022, where many of the Grand River Valley Area Vineyards had little or no fruit due to a late frost.

 

grape

 

 

One other problem with a late snow after trees have leaved out, the weight of the snow can break branches as was the case with this Norway Maple.

 

norway1

 

norway2

 

In the case of evergreens, they can begin to grow

 

ev

 

 

 

 

and get burned by a late frost.

 

frost2

image provided by Dr. David Shetlar, OSU.

 

 

 

 

But you can’t control Mother Nature!

 

In conclusion:

Late Snow – not too many problems for plants

Consistent cold temperatures – plants stay dormant.

Any early warm up and spring followed by mild night temperature at or above freezing – all is well.

Warm temperatures sustained over several days or weeks then a series of freezing temperatures in the low 20’s and teens – expect flower damage and possible stem dieback.

A repeat of 2015’s polar vortex – plan on replacing some plants.

But just snow in March or April? In most cases, not a problem.