How close you can plant herbs together depends entirely on the specific type of herb you are growing. There is no single universal distance that applies to all varieties, as each has a unique growth pattern, mature size, and need for resources. Proper spacing is a practical consideration that directly influences the health and productivity of your herb garden, maximizing the amount of flavorful foliage you can harvest. Ignoring these needs can lead to poor plant performance and low yields.
Understanding Herb Growth and Spacing Needs
Spacing between herbs is a preventative measure designed to mitigate common problems that arise from overcrowding. One of the most important functions of adequate spacing is to promote air circulation around the foliage. When plants are packed too tightly, the lack of airflow traps moisture on the leaves, creating a humid microclimate that encourages the development of fungal diseases like powdery mildew or rust. Ensuring sufficient space allows the sun and wind to dry the leaves quickly, significantly reducing the risk of these infections.
Plants that are placed too close together will also compete for limited resources both above and below the soil line. They will struggle for access to sunlight, which can lead to stunted growth and reduced leaf production. Below the surface, root systems will aggressively compete for water and essential nutrients, ultimately stressing the plants and diminishing the overall quality and flavor of the herbs.
The most fundamental consideration for spacing is the plant’s mature size, not its size when it is first planted. Spacing recommendations are based on the expected final width and height of the herb once it is fully grown. While herbs grown in containers can sometimes be planted slightly closer due to the natural restriction of the pot, in-ground planting requires more generous distances to allow the root systems to fully develop.
Specific Spacing Guidelines for Common Herbs
Bushy and Clumping Herbs
Herbs with a bushy or clumping growth habit require moderate spacing to achieve their full, dense potential. Basil, a popular annual herb, generally needs about 10 to 12 inches of space between plants to allow its large leaves to develop without shading its neighbors. Oregano, thyme, and sage, which are often woody perennial herbs, also fall into this category and thrive with similar spacing.
Thyme and sage should typically be planted about 12 inches apart to allow for proper airflow and lateral growth. Oregano, which can spread slightly more than the others, usually requires 9 to 12 inches of separation to form a healthy clump. Providing this distance ensures that the inner parts of the plant receive enough light and air to prevent the center from becoming woody or dying back.
Tall and Upright Herbs
Upright herbs that grow primarily in height, such as dill and fennel, need moderate spacing to prevent competition for vertical light and to provide structural stability. Dill should be planted with approximately 10 to 12 inches of distance between plants to support its slender, tall stems and prevent them from collapsing onto one another. Fennel benefits from spacing up to 18 inches.
Cilantro, which is a taproot plant, also benefits from generous spacing, often needing 12 to 18 inches between mature plants, particularly if grown for seed production. These plants benefit from being positioned at the back of a garden bed to prevent them from shading out lower-growing herbs.
Sprawling and Running Herbs
Herbs that spread aggressively through underground runners or vigorous above-ground growth require the largest amount of space and often need isolation. Mint is the most notable example, as its rhizomes can quickly colonize an entire garden bed, choking out less vigorous plants. For this reason, mint should always be planted in its own container or a dedicated, contained area.
Lemon balm, a member of the mint family, also spreads vigorously, primarily by self-seeding. It should be given a minimum of 18 to 24 inches of space to accommodate its mature size, or it can be isolated in a large pot to manage its sprawling habit and prevent excessive reseeding. Containment is the most effective spacing strategy for these types of herbs.