Impatiens Suddenly Died With Stem Turning Light Brown From Bottom Up

Question From: Spring Hill, Queensland, Australia
Q: What is wrong with my Patience flower, it was blooming and very quickly it died. It turned light brown from the bottom of the stem, and it become very thin and light brown to the start of stem only. Thank you.
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A: Looks to me like cold weather. Best And Happy Yardening, Nancy