Answer: Perennial sweet peas will come back year after year. The roots are hardy but the tops are not, which is why the cold weather killed the stems and foliage back. Cut everything down to soil level and wait for new growth when the weather warms in the spring. Next autumn, when frost nips the tops of the plants, cut them back and remove the foliage from the garden. If you leave the old, dead plant parts in the garden, you run the risk of diseases overwintering and infecting new growth as it emerges in the spring.
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