When is the best time to plant window box herbs?
Written by
Michael Sullivan
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.The best conditions for most window box herbs occur in the spring, after the last frost. Basil, rosemary, and thyme do best when the soil temperature reaches 60°F (15°C). This timing gives the Mediterranean herbs a full season of growth in which to develop a strong root system before winter arrives.
Fall planting favors heat-intolerant herbs such as parsley, chives, and cilantro. These herbs flourish in cooler weather and do not bolt in summer. Six weeks should be allowed for them to get established before the first frost. Mulch them heavily for winter protection when planted in moderate climates.
Cilantro is sensitive to heat and performs best in autumn situations. Plant seeds when the temperature is below 75°F (24°C) for the longest harvest. Mediterranean herbs such as oregano require warmer spring soil, above 55°F (13°C), for germination and growth.
Spring Stars
- Basil: Plant after soil reaches 60°F (15°C)
- Rosemary: Needs nighttime temps above 50°F (10°C)
- Thyme: Sow seeds 2 weeks before last frost date
Fall Champions
- Parsley: Transplant seedlings 6 weeks before frost
- Chives: Divide and plant in early autumn
- Cilantro: Direct sow when temps dip below 75°F (24°C)
Special Cases
- Mint: Plant anytime except peak summer heat
- Oregano: Requires spring planting for woody stems
- Dill: Succession plant every 3 weeks spring through fall
Adapting to microclimate conditions can help planting succeed. For instance, south-facing walls warm quickly in the spring and can allow for early planting. North-facing locations take longer to warm up, and planting may need to be delayed. Always check the soil temperature with a thermometer to ensure the temperature is suitable before planting heat-sensitive varieties.
Lengthen seasons using protection options. Cloches can help facilitate early spring plantings before the risk of frost. Shade cloth can protect your fall-planted cilantro if an unexpected heatwave occurs. Both methods bridge gaps in weather and provide continuous herb production.
Read the full article: 10 Best Window Box Herbs for Your Kitchen
