gardens
P L A N T S C I EN C E
S E P T E M B E R 2 012
Cool Season vs. Warm Season Vegetables
Chris Zdorovtsov | Community Development Field Specialist
COOL SEASON CROPS
Cool season crops are plants that have adapted to cool climates. Most cool season crops prefer temperatures
below 70°. When the temperature starts to climb over their comfort zone in the spring or early summer they tend
to bolt, which means they produce a seed stalk. When this happens the plant becomes too woody or bitter for us
to eat.
Try growing these in the spring for an early start in the garden or in the late
summer for a fall harvest. In South Dakota these would be typically planted by
mid-April to early May for a spring planting and by mid-August to mid-September
for a fall planting. For fall crops, lettuce may need to be started in the cooler
indoors and transplanted, since it will not germinate at higher soil temperatures.
The best way to grow cool season crops in the summer is to shade them to keep
them cooler. Cool season crops include but are not limited to cabbage, carrots,
broccoli, spinach, onions, radishes, peas, lettuce and turnips.
WARM SEASON CROPS
Warm season crops are plants that have adapted to warmer climates and
are very sensitive to frosts. They must be planted after the last frost in the
spring when the soils have warmed and night temperatures stay above 4550 degrees. In South Dakota this can range from early May to early June.
Allowing the soil to warm further will create optimal growing conditions for
these plants. Examples of these crops are tomatoes, peppers, eggplant,
watermelon, squash, beans and sweet corn.
Warm season crops are susceptible to chilling injury. The cold temperatures
cause plant growth failure. This results in rapid respiration, molds and rots on
the plant and bitter flavors. This most often happens when the temperature drops below 45-50°. Cucumbers,
tomatoes and tropical fruits and foliage are very sensitive to chilling injury.
Source:
Vegetables, National Junior Hortiuculture Association, S. Schoneweis, Dept of Horticulture, Univeristy of
Nebraska-Lincoln. . Retrieved from http://www.njha.org/projects_hortid_vegetables.html
Sout h Dakot a St at e Univer s i t y, S out h D a kot a c ount i es , a nd U.S. D epa r t m ent of Agr i c ul tur e c ooper a t i ng . So u th D a ko t a
St at e Univer sit y is an Aff i r m a t i ve Ac t i on/E qua l Oppor tuni t y E m pl oyer a nd offer s a l l benef i t s , s er v i c es , e d u c a ti o n , a n d
employment oppor tunit ies w i t hout r ega r d for r a c e, c ol or, c r eed, r el i gi on, na t i ona l or i gi n, a nc es t r y, c i t i ze n s h i p , a g e ,
gender, sexual or ient at ion , di s a bi l i t y or Vi et na m E r a Vet er a n S t a tus .
Publication: 06-1018-2012
Contact: Chris Zdorovtsov
Page 1
iGrow | A Service of SDSU Extension