Purslane, a genus of plants known as Portulaca, is a warm-season annual that has been used in various ways for centuries. This plant family includes both spontaneous varieties often considered weeds and carefully bred ornamental cultivars. The question of its suitability as a ground cover depends entirely on the specific variety and the gardener’s objective. This article will examine the biological attributes of purslane and distinguish between its common and ornamental forms.
Characteristics That Define Its Suitability
Purslane is characterized by a prostrate, mat-forming growth habit, which makes it an effective ground cover. The plant’s stems grow low to the soil surface, spreading out to form a dense canopy that shades the ground. This physical barrier helps suppress the germination of other unwanted plants by blocking sunlight.
The succulent nature of purslane’s leaves and stems allows it to store water, contributing to an impressive tolerance for heat and drought. This adaptation allows the plant to thrive in harsh conditions, such as in cracks in pavement or areas with poor, compacted soil. As a living mulch, the thick growth keeps the soil beneath it cooler and retains moisture, benefiting nearby plants in arid environments.
The rapid growth cycle allows purslane to establish quickly, providing fast coverage in newly planted or disturbed areas. This quick establishment helps stabilize the soil, which can reduce erosion on exposed slopes or between stepping stones. Its ability to grow in low-fertility conditions makes it a low-maintenance option for challenging spots.
Distinguishing Between Weed and Ornamental Varieties
The term “purslane” most commonly refers to Portulaca oleracea, often called common purslane, which is regarded as a garden weed. This variety is characterized by fleshy, paddle-shaped leaves and small, five-petaled yellow flowers that usually open only during the sunniest part of the day. Common purslane possesses a reddish stem and is notorious for its aggressive self-seeding, with a single plant capable of producing over 200,000 viable seeds.
In contrast, ornamental varieties, such as Moss Rose (Portulaca grandiflora), are intentionally used for landscaping purposes. These cultivars are bred for showier flowers, which come in vibrant colors like pink, orange, white, and red, and have larger, more numerous petals. Ornamental purslane often has thinner, needle-like foliage compared to the common variety.
The distinction is significant because the common type spreads vigorously and can re-root easily from small stem fragments left behind after weeding. Ornamental varieties generally have a more controlled, mounding growth habit and are less likely to become invasive through rampant self-seeding.
Installation and Control Strategies
Installation of Ornamental Varieties
Successful installation begins with choosing a location that receives at least six to eight hours of direct sunlight daily. The plants require well-draining soil, often preferring a sandy or gravelly composition, and should be spaced to allow for their trailing or mounding spread. While they are drought-tolerant, moderate watering is necessary during establishment. Ensure the top inch of soil is dry before re-watering to prevent root rot.
To maintain a dense, uniform appearance, ornamental purslane can be trimmed or lightly sheared when it becomes leggy, which encourages continuous flowering throughout the warm season. A light application of a balanced, slow-release fertilizer once or twice during the growing season can support vigorous blooming.
Controlling Common Purslane
Managing unwanted common purslane requires vigilance, primarily focusing on preventing the plant from setting seed. Since the seeds can remain viable in the soil for decades, any plants should be removed before their tiny seed capsules mature. When weeding, it is essential to remove the entire plant and dispose of it away from the garden, as the fleshy stems can re-root if left on moist soil.
Applying a thick layer of organic mulch, at least three inches deep, can effectively suppress the germination of purslane seedlings by blocking light. Additionally, avoiding deep cultivation of the soil helps, as disturbing the ground brings dormant seeds to the surface where they can germinate. For large, persistent infestations, methods like soil solarization, which uses clear plastic sheeting to heat the soil during the summer, can kill the seeds before planting begins.