Can herbs survive winter in window boxes?
Written by
Michael Sullivan
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.To survive the winter season, window box herbs require care that varies according to plant usage and climatic conditions. Perennial herbs, such as rosemary and thyme, can safely survive the winter months in mild climates if adequately protected. At the same time, annual varieties, like basil, are killed by the first frost and must be replanted in the spring. The grower must understand these differences to apply the most appropriate methods for winter survival.
Insulate perennials in Zones 7-10 with simple insulators. Wrap boxes in burlap or bubble wrap before freezing nights. Move containers against house walls for added heat. Cover plants with frost cloth when the temperatures drop below freezing.
During brutal winters, move herbs native to the Mediterranean to sunny windows in the house. Rosemary and thyme prefer bright light and less watering. Bring the plants indoors for about a week to prevent them from experiencing shock. Check for pests before bringing them inside.
Mild Climate Protection
- Insulate boxes with bubble wrap or burlap layers
- Group containers together against sheltered walls
- Cover plants with frost cloth during freezing nights
Indoor Transition
- Gradually reduce outdoor time over 7 days
- Place near sunny windows with 6+ hours light
- Water only when soil is completely dry
Annual Herb Management
- Harvest remaining basil before first frost
- Remove dead plants and refresh soil for spring
- Start new seeds indoors 8 weeks before last frost
When preparing your herbs for winter, the task of preparing boxes is the same regardless of the type of herb. Before you put the plants away for winter, remember to clear drainage holes into which water can freeze. Mulch is a good option for soil protection. Water less often, as plants will enter dormancy and will want less water.
Preparations for spring get underway in late winter. In February, when it's time to prune woody perennials, we can start stimulating new growth. Start basil seeds indoors six weeks before the expected final frost. Refresh the soil in containers for replanting by mixing in compost and coarse sand.
Successful overwintering maintains the continuity of your herb garden. Perennials return stronger each year while annuals offer renewal opportunities. Follow these practices for year-round enjoyment of homegrown flavors.
Read the full article: 10 Best Window Box Herbs for Your Kitchen
