City	Sow outdoors	Last frost
Baltimore	Mar 24 to Apr 14	Mar 24
Columbia	Apr 5 to Apr 26	Apr 5
Frederick	Apr 2 to Apr 23	Apr 2
Germantown	Apr 14 to May 5	Apr 14
Waldorf	Apr 17 to May 8	Apr 17
Silver Spring	Apr 10 to May 1	Apr 10
Ellicott City	Apr 2 to Apr 23	Apr 2
Glen Burnie	Apr 10 to May 1	Apr 10
Gaithersburg	Apr 1 to Apr 22	Apr 1
Rockville	Apr 1 to Apr 22	Apr 1
Bethesda	Apr 9 to Apr 30	Apr 9
Dundalk	Mar 24 to Apr 14	Mar 24
Bowie	Apr 22 to May 13	Apr 22
Severn	Apr 10 to May 1	Apr 10
Bel Air South	Apr 10 to May 1	Apr 10
Towson	Apr 2 to Apr 23	Apr 2
Aspen Hill	Apr 1 to Apr 22	Apr 1
Wheaton	Apr 1 to Apr 22	Apr 1
North Bethesda	Apr 1 to Apr 22	Apr 1
Potomac	Apr 1 to Apr 22	Apr 1
Odenton	Apr 10 to May 1	Apr 10
Hagerstown	Apr 11 to May 2	Apr 11
Catonsville	Mar 24 to Apr 14	Mar 24
Essex	Mar 24 to Apr 14	Mar 24
Annapolis	Mar 27 to Apr 17	Mar 27
Severna Park	Mar 27 to Apr 17	Mar 27
Clinton	Apr 3 to Apr 24	Apr 3
Olney	Apr 1 to Apr 22	Apr 1
Randallstown	Apr 2 to Apr 23	Apr 2
Owings Mills	Apr 2 to Apr 23	Apr 2
College Park	Apr 10 to May 1	Apr 10
Chillum	Mar 29 to Apr 19	Mar 29
Pikesville	Apr 2 to Apr 23	Apr 2
Montgomery Village	Apr 14 to May 5	Apr 14
Salisbury	Apr 3 to Apr 24	Apr 3
Pasadena	Apr 10 to May 1	Apr 10
Milford Mill	Apr 2 to Apr 23	Apr 2
Middle River	Mar 24 to Apr 14	Mar 24
Bel Air North	Apr 10 to May 1	Apr 10
Eldersburg	Apr 2 to Apr 23	Apr 2
Parkville	Apr 2 to Apr 23	Apr 2
Laurel	Apr 5 to Apr 26	Apr 5
Crofton	Apr 22 to May 13	Apr 22
Clarksburg	Apr 14 to May 5	Apr 14
Perry Hall	Apr 2 to Apr 23	Apr 2
Carney	Apr 2 to Apr 23	Apr 2
Reisterstown	Apr 2 to Apr 23	Apr 2
South Laurel	Apr 5 to Apr 26	Apr 5
Lochearn	Apr 2 to Apr 23	Apr 2
Ilchester	Apr 10 to May 1	Apr 10
Fairland	Apr 5 to Apr 26	Apr 5
Elkridge	Apr 10 to May 1	Apr 10
Ballenger Creek	Apr 2 to Apr 23	Apr 2
Fort Washington	Apr 3 to Apr 24	Apr 3
North Laurel	Apr 5 to Apr 26	Apr 5
Edgewood	Apr 10 to May 1	Apr 10
Greenbelt	Apr 10 to May 1	Apr 10
Suitland	Mar 29 to Apr 19	Mar 29
Landover	Mar 29 to Apr 19	Mar 29
North Potomac	Apr 1 to Apr 22	Apr 1
Arnold	Mar 27 to Apr 17	Mar 27
Cockeysville	Apr 2 to Apr 23	Apr 2
Camp Springs	Apr 3 to Apr 24	Apr 3
Langley Park	Apr 10 to May 1	Apr 10
Hyattsville	Mar 29 to Apr 19	Mar 29
Arbutus	Mar 24 to Apr 14	Mar 24
Rosedale	Mar 24 to Apr 14	Mar 24
Westminster	Apr 24 to May 15	Apr 24

Questions

When should I plant sunflowers in Maryland?

In Baltimore, sow outdoors from March 24 to April 14. Across Maryland the window opens between March 24 and April 24, depending on the local last frost.

How is this date worked out?

Sow outdoors up to 3 weeks after the last frost. Frost dates are NOAA 1991–2020 averages for the weather station nearest each city.