Two Part Advisory: 1) What Just Happened This Morning? 2) What’s Ahead for Tomorrow Morning? (6:30pm, Sun., 3/29/15)

— Written By Barclay Poling

This advisory is now organized in two parts:

3 p.m. update on 3/29 – dealing with what just happened this morning

6:30 p.m. update on 3/29 – evaluating potential for frost on Monday morning

Note: In areas where skies may be clear tonight, and minimum temps of 35 or below are expected, BE SURE TO SET YOUR FROST ALARM!

Part 1. A mid-afternoon update on 3/29 – dealing with what just happened this morning

Across the region last night and this morning we experienced a classic black frost. Many piedmont locations were in the mid-20s, like Upper Piedmont Research Station in Reidsville (Fig. 1). Temperatures began to plummet even before sunset because of very dry air conditions.

reid useFig. 1. Reidsville had a low of about 25.7 at 6 a.m. A high was reached on Saturday of 42.6 F around 4 p.m., and then temperatures began to tumble in the very late afternoon. This rapid drop was associated with exceptionally dry air.

reid dp use Fig. 2. Even by about 3 p.m. yesterday, dewpoints were already down around 10 F.

I have had a few reports from the field today, but would be very happy to hear from you! Thus far, I am not aware of any significant blossom or flower bud injury?

concordTable 1. This is the AWIS detailed forecast for a location where some damage has been reported today (Concord)

Grower in Concord, NC (4 p.m.)

“Just left the field and we appeared to have some decent cold damage from the event last night. We used our row covers and most held in place. Attached are images of what the buds look like currently, which is different than how it looked a day ago. We have many buds that are still a healthy yellow with green insides (there is a bisected picture attached), we have other buds that are brown but still have green/healthy insides, finally we have buds that are brown with brown (below) insides.

dead bloomFig. 1. Brown outside and inside – Concord, NC

brown out small

Fig. 2. Bloom killed in black frost, 3/29/15, Concord NC

Editor’s note – please let us know your minimum this morning, and what did Skybit forecast? What was the actual low? What weight row cover? Glad that most of the crop is ok.

VA Beach Feedback

I did receive this note from Tom Baker, VA Beach, a moment ago:

“I’ll go out a little later (3:30-4 p.m.) and take another look at blossoms that were in the few not-covered Camarosa rows as well as the not-covered Chandler rows (all rows had drip last night). Covert damage may not show up yet but overt damage should be evident. Will of course look at covered plants when we remove covers tomorrow.”


His questions earlier today were:

1. How long after a freeze event should one wait before an accurate evaluation of blossom damage is possible?
2. How long after a frost event should one wait before an accurate evaluation of blossom damage is possible?
3. How long after a frost and freeze event should one wait before an accurate evaluation of blossom damage is possible?

My reply:  You can begin to evaluate open blossom, popcorn and flower buds within a few hours for damage. Instead of “bright yellow” centers you have what are often referred to as “black eyes.”  This sort of injury can be observed by mid-morning following a radiation frost (white or black), frost/freeze, or windborne freeze. With a light frost, you may not see this more obvious damage (brown centers), but there can be partial injury to the flower that shows up later in the season as very bumpy looking fruit. Something that I believe everyone should be on the look-out for is possible damage to tight flower buds last night?

damageFig. 3. Damage to open blossoms can be seen relatively soon after the cold event

 flower budFig. 4. Growers will want to check inside the flower buds for damage. In a freshly cut flower bud you will not likely see this kind of blackening so quickly after the cold event (this photo was taken of an emerged flower bud that had been injured during late winter, and my site visit was a few weeks following the event).

healthy budFig. 5. A healthy flower bud!

Crop damage report (5 p.m.) – Va Beach (an example where drip and no cover was unsuccessful)


I checked blossoms about 5 p.m. today.

Camarosas in two rows at Pungo that had no row covers and were dripped starting at 4 a.m. had about 40-50% blossom loss (flower eyes “brown,” not yet “black.”  This is a disappointing surprise since air temp didn’t fall below 28.9 (WeatherUnderground), air was dry (dew point in single digits after 11 p.m.), and wind was mostly 5 to 10 mph and never less than 3.5.

Hindsight says perhaps drip should have been started earlier, but maybe wind negated effect of drip where there were no row covers?

A peek under row covers where drip was also used showed no damage to Camarosa or Chandler blossoms.

Drip ran in the entire field; no rows with “row cover and no drip.”


Tom & Anne Baker and Amanda McCann

Leaving covers on another day?  Tom Baker, like many other seasoned growers in the region,  know that after a cold event such as last night, it is a good idea to get prepared for a one, or possibly even a second “after-shock,” and the reason he is leaving his covers on today (Sunday), is due to the potential for a frost tomorrow morning.

Part 2. Evening update

Clayton – clouds moving in tonight and rains tomorrow morning

However, as of this evening, it would now appear that overcast skies and even rain tomorrow morning minimize chance of frost at Clayton. Here is the AccuWeather for Clayton as of 6 p.m.:

clayton update accu

Rains in morning:


My evening SkyBit shows that the minimum expected in canopy tomorrow is now 35 (it was 34 this morning). There doesn’t appear to be much chance of frost.

Here is the follow-up SkyBit for Clayton:

clayton evening

Latest minimum temp map for NC (6 p.m., 3/29) 6. Minimum temperatures for Monday, 3/30

It would be helpful for you to click on the live link below to see what conditions will be like in your area tomorrow morning. For example, we know overcast skies and then rains are moving into much of the state tonight, but in areas on the map above where temperatures will be coldest tomorrow morning, it would not hurt to see if skies might be clear tomorrow morning, and if they are, a FROST might occur. In areas where skies may be clear tonight, and minimum temps of 35 or below are expected, BE SURE TO SET YOUR FROST ALARM!

An example, NEW BERN, NC

new bernNote that NEW BERN will likely have clear skies and potential exist for frost at 4 a.m.

AWIS Detailed Hourly Forecast for Locations Across NC


Ahoskie-Tri-Cou Albemarle_AP Andrews Asheboro
Asheville_Munic Beaufort-Michae Boone_NC Burlington-Burl
Cape_Hatteras_AG Chapel_Hill-Hor Charlotte Cherry_Point
Clinton_NC Concord_NC Currituck_NC Edenton-Northea
Elizabeth_City Elizabethtown_NC Erwin-Harnett_C Fayetteville_AP
Fort_Bragg/Simm Franklin/Macon_C Gastonia-Gaston Goldsboro_AFB
Goldsboro_NC Greensboro Greenville_AP_NC Hickory
Jacksonville Jacksonville_(A Jefferson_AP_NC Kenansville-Dup
Kill_Devil_Hills Kinston_AP Lexington-David Lincolnton_AP
Louisburg_NC Lumberton_AP_NC Mackall_AAF Manteo/Dare_Co
Maxton Mcalf_Bogue_Fiel Monroe_AP_NC Morganton-Morga
Mount_Airy-Moun New_Bern North_Wilkesbor Oxford_NC
Piney_Island_Bom Pope_AFB Raleigh-Durham Reidsville_AP
Roanoke_Rap_AP Roanoke_Rapids_R Rockingham_NC Rocky_Mount-Wils
Roxboro_AP Rutherfordton Salisbury-Rowan Sanford_NC
Shelby_AP_NC Smithfield_AP Southern_Pines Southport_NC
Statesville-Sta Tarboro_AP Wadesboro_AP Washington-Warr
Whiteville_NC Wilmington_AP_NC Winston-Salem

Virginia: AWIS VA Mar 29 – Apr 5 7. Minimums for Monday morning in VA and Mid-Atlantic 8. Minimums for Tuesday morning


Abingdon Ashland_VA Charlottesville Chesapeake-Ches
Culpeper Danville Dublin/New_Riv Emporia_VA
Farmville Fentress_Naval_A Fort_Belvoir/Da Fort_Eustis/Fel
Franklin/J_B_Ro Hillsville Hot_Springs/Ing Jonesville_AP
Langley_AFB Leesburg/Godfre Louisa-Louisa_C Lynchburg
Manassas_Muni(A Marion/Wythev Martinsville Mecklenburg/Bru
Melfa/Accomack Newport_News Norfolk_Hampton_ Norfolk_NAS
Norfolk_VA Oceana Orange_VA Petersburg_(AWO
Quantico Richlands_AP Richlands_VA Richmond
Richmond_Chester Roanoke Shannon_Arpt Stafford_AP_VA
Staunton-Shenan Suffolk-Suffolk Tappahannock_AP Virginia_Tech_A
Wakefield_AP Wallops_Island Warrenton_Fauqui Washington_Dulle
West_Point_VA Williamsburg_VA Winchester_Rgnl Wise/Lonesome_P

South Carolina:


Aiken_AP Anderson_Co_Air Barnwell_AP Beaufort_Cnty_AP
Beaufort_SC Bennettsville_Je Camden_AP Charleston_Exec_
Charleston_Muni Cheraw_AP Chester_AP Clemson-Clemson
Columbia-Columb Columbia/McEnti Columbia_Metro Conway_AP
Darlington Florence_SC Georgetown_AP_SC Greenville_Donal
Greenville_Down Greenville-Spart Greenwood-Green Hartsville_AP
Hilton_Head_AP Kingstree_AP Lancaster-McWhir Laurens_AP
Manning_AP Marion_AP_SC Moncks_Corner_AP Mount_Pleasant_A
Myrtle_Beach Newberry_AP North_Myrtle_Be Orangeburg-Oran
Pickens_AP Rock_Hill Spartanburg_Down Summerville_AP
Sumter_AP Sumter_SC Walterboro_AP Winnsboro_AP



Chattanooga/Lov Clarksville_TN Crossville_AP Dyersburg
Elizabethton_AP Jackson_TN Knoxville_AP Memphis_AP
Millington Nashville_Metro Oak_Ridge_TN Smyrna



Bowling_Green Covington Danville-Powell_ Fort_Campbell
Fort_Knox/Godma Frankfort_AP Glasgow_KY Henderson_City
Jackson_KY Lexington_KY London_Corbin Louisville_AP
Louisville/Bowm Middlesboro_AP Monticello_KY_AP Murray_AP
Owensboro_AP Paducah Richmond_Madison Somerset(AWOS)

Maryland: AWIS MD Mar 29-Apr 5


Aberdeen Andrews_AFB Annapolis_Naval Baltimore_Sci_Ce
Baltimore/Wash Cambridge/Dorche College_Park_AP Cumberland_AP
Easton_MD Fort_Meade Frederick_MD Gaithersburg_AP
Hagerstown_AP Leonardtown Middle_River Oakland_MD_AP
Ocean_City_AP Patuxent_River Salisbury Stevensville_AP
St_Inigoes/Webst Washington_DC_AP Westminster_AP


Please send photos and feedback on how things turned out from last night. Thanks

Good luck tonight!

Dr. E. Barclay Poling
Professor Emeritus (Strawberry Plasticulture Researcher)
Department of Horticultural Science
Campus Box 7609, 162A Kilgore Hall
NC State University
Raleigh, NC 27695-7609
“An idealist believes the short run does not count. A cynic believes the long run does not matter. A realist believes that what is done or left undone in the short run determines the long run.”

Sidney J. Harris, In: Reclaiming a Lost Heritage – Land-Grant & Other Higher Education Initiatives for the Twenty-first Century