Cultivating herbs successfully requires understanding the specific climate in which they will grow. This guide provides a schedule for planting herbs in USDA Hardiness Zone 7, a region with a moderate growing season. Timing is paramount; planting too early risks damage from late frosts, while planting too late shortens the harvest window. Recommendations are divided based on a plant’s tolerance for cold, distinguishing between hardy varieties and tender herbs that demand consistent warmth.
Understanding the Zone 7 Climate Window
USDA Hardiness Zone 7 encompasses regions where the average minimum winter temperature falls between 0°F and 10°F. The most important factor for spring planting is the average last expected frost date, which typically occurs between late March and early April. This date signals the transition to the primary growing period.
Successful planting also relies heavily on soil temperature. Many seeds and seedlings will not germinate or establish healthy roots until the soil has warmed sufficiently. A soil thermometer is a valuable tool, as soil often warms more slowly than the air above it. Local microclimates can also shift this planting window slightly.
Planting Timing for Hardy Herbs
Hardy herbs, including perennials, biennials, and certain annuals, tolerate cool soil and light frosts. These herbs can be planted outdoors much earlier than warm-weather counterparts, utilizing the full Zone 7 growing season. Planting these varieties is safe to begin four to six weeks before the average last frost date, starting in late February or early March.
Perennial herbs can be transplanted from nursery starts or established divisions early in the spring. Examples include:
- Chives
- Oregano
- Mint
- Thyme
Chives are highly cold-tolerant and establish readily when the soil temperature is consistently above 50°F. Thyme and Oregano benefit from an early start to develop strong root systems before summer heat arrives.
Annuals and biennials such as Cilantro, Dill, and Parsley are excellent candidates for direct sowing during this early window. Cilantro thrives in cooler weather and will quickly bolt once temperatures rise, making early spring planting necessary for a leaf harvest. Parsley, a biennial, produces foliage throughout its first season and can be sown once the soil temperature is reliably above 50°F.
Direct sowing is preferred for herbs like Dill, which develops a deep taproot and can suffer transplant shock. These cool-weather herbs can withstand a light freeze, but covering them with a row cover offers protection if a hard frost is forecast. Succession planting—sowing a new batch of seeds every few weeks—is effective for Cilantro to maintain a continuous supply of fresh leaves before the plant succumbs to summer heat.
Planting Timing for Tender Herbs
Tender herbs are sensitive to cold and require warm soil and consistent air temperatures to thrive. These plants must not be placed outdoors until all risk of frost has passed, which in Zone 7 means waiting until after the first week of April, often into early May. The minimum soil temperature for these herbs often needs to be consistently above 60°F.
Basil is a well-known tender herb, and its seeds require a soil temperature of around 70°F for successful germination. Planting Basil too early will stunt its growth or cause the leaves to blacken if temperatures dip below 50°F. It is best to wait until the weather has settled, often around Mother’s Day, before transplanting it into the garden.
Tender perennials, such as Rosemary, Marjoram, and Stevia, are typically grown as annuals in Zone 7 unless overwintered indoors. To get a head start, seeds for these herbs should be started indoors six to eight weeks before the last expected frost date. This indoor start allows the plant to develop a substantial root mass before outdoor exposure.
Before transplanting any tender herb seedlings outdoors, they must undergo “hardening off.” This gradual acclimatization involves exposing the young plants to outdoor conditions for increasingly longer periods over one to two weeks. This prepares them for the intensity of direct sunlight and wind. Failing to harden off seedlings can result in sunscald or shock, leading to delays in growth or plant death.