Thyme is a perennial herb, prized for its aromatic foliage in culinary dishes and its dense habit as a ground cover. Maximizing the harvest or coverage in limited space often involves dense planting techniques, such as square-foot gardening. This method requires precise planning to ensure each plant receives adequate resources while promoting a bushy growth habit. The specific number of plants that can thrive within a single square foot depends entirely on the variety’s natural growth pattern and the gardener’s ultimate goal.
Determining Plant Count by Thyme Type
The number of thyme plants per square foot is dictated by whether the variety grows upright for harvesting or spreads horizontally for coverage. Culinary thyme varieties, primarily Thymus vulgaris, exhibit an upright, shrubby growth habit, with the goal of maximizing leaf production. The standard dense planting guideline is four plants per square foot, corresponding to placing one transplant every six inches in a grid pattern. This close spacing encourages upward growth rather than outward spread, resulting in a higher yield of flavorful stems and leaves.
Creeping thyme varieties, such as Thymus serpyllum, are generally used for ornamental purposes like filling spaces between pavers or acting as a lawn substitute. These varieties require less density due to their natural horizontal spread. For quick, tight coverage, four plants per square foot (six-inch spacing) is appropriate. Alternatively, for larger areas or between widely spaced stepping stones, use one to two plants per square foot, spaced 9 to 12 inches apart. This lower density saves on initial plant costs and allows the thymes to naturally root as they sprawl, though it may take a second growing season to achieve full coverage.
Preparing the Soil and Planting Method
Successful dense planting requires an environment that mimics thyme’s native, arid Mediterranean habitat. Thyme is highly intolerant of wet conditions, making exceptional drainage the most important soil requirement. An ideal planting medium should be loose and lean, incorporating coarse material like sand or fine gravel to prevent water retention. This herb prefers a neutral to slightly alkaline soil pH, which can be achieved by amending acidic soils with a small amount of lime or wood ash.
It is recommended to use small transplants, often referred to as plugs, rather than starting from seed for dense planting. Thyme seed germination is slow and unreliable, complicating the uniform spacing required in a square-foot grid. Before planting, the area should be measured and marked precisely, perhaps using a simple template, to ensure accurate six-inch spacing. When placing the plugs, gently separate any tightly bound roots and set the plant so the top of the root ball is level with the surrounding soil surface. The woody base, or crown, must remain above the soil line to prevent moisture from accumulating and initiating stem rot.
Managing Dense Thyme Planting
Growing thyme at high density requires specific maintenance practices to counteract the risk of fungal issues and root rot. Because the closely spaced foliage can trap moisture and restrict airflow, regular pruning is necessary to maintain plant health. Harvesting should involve cutting back stems by no more than one-third of their length, preferably just before flowering when essential oil content is at its peak. This practice encourages fresh, non-woody growth while opening the canopy for better air circulation.
The watering regimen must be carefully managed to avoid oversaturation, a common cause of failure in dense thyme plantings. Once the transplants are established, thyme requires infrequent but deep watering, allowing the soil to dry out completely between applications. Shallow, frequent watering is detrimental as it keeps the upper soil layer constantly moist, promoting disease near the crown. Thyme thrives in poor soil, so fertilization should be minimal or avoided entirely. Rich soil with high nitrogen encourages lush vegetative growth that is less concentrated in flavor and can lead to weak plants susceptible to disease in a dense environment.