The Minimum Temperature for Petunia Plants

Temperature Requirements

• Petunia seeds germinate when the temperature is 70 to 85 degrees F. Once germination occurs the seedlings enjoy a daytime temperature of 65 degrees and a nighttime temperature of 55 to 65 degrees, according to the University of Minnesota.

Considerations

• Begin to harden petunia seedlings off by placing them outside during the day but bringing them in during the night. Plant the seedlings into the soil when the soil temperature is a minimum of 60 degrees.

Warning

• Petunias must be maintained at 65 degrees F to insure adequate growth and blossom production. The plants can tolerate extreme heat with adequate water, but when the first hard frost occurs in the fall the plants normally die.