Perennials in Window Boxes (Zone 5): Better in Pots

Zone 5 gardener wants perennials in window boxes but worries about winter survival.

Window Boxes Are Poor for Perennial Overwintering

Shallow soil freezes solid, killing roots. Perennials need ground insulation.

Solution: Pot-and-Rotate System

• Grow perennials in pots sunk into boxes.
• Rotate: 2 pots in sun, 1 in box; swap weekly.
• In winter, move pots to protected spot (garage, cold frame) or bury in ground.

Plant Suggestions

• Spring bulbs (alliums, alyssum) in pots.
• Short dahlias for summer.
• Annuals (geraniums, petunias) for reliable season-long color.

Perennials in boxes = high maintenance. Pots + rotation = success.