The persistence of clover, a common plant found globally in lawns and fields, often confuses homeowners and gardeners. Whether clover returns every year depends entirely on the specific species and the local growing environment. Some varieties are true perennials that regrow annually from the same root system. Others are annuals or short-lived biennials that rely on new seed production to reappear each season.
Identifying Common Clover Types and Their Life Cycles
The most common clover found in North American lawns is White Clover (Trifolium repens), and it is a genuine perennial that returns year after year. This low-growing species survives the winter by storing energy in its established root system and its creeping stems, known as stolons. White Clover plants can persist indefinitely in favorable conditions, continuously spreading through vegetative means and seed production.
Red Clover (Trifolium pratense) is classified as a short-lived perennial or a biennial, depending on the climate. Although it may live for more than one year, its productivity typically declines significantly after the second or third season before the original plant dies. It often appears to return annually because it is an effective self-seeder, with new seedlings replacing the expiring parent plants.
Crimson Clover (Trifolium incarnatum), known for its crimson-red flower heads, is a cool-season annual that completes its entire life cycle in a single year. Seeds germinate in the autumn, grow throughout the winter and spring, and the plant dies after setting seed in the late spring or early summer. Its yearly “return” is solely dependent on dropping enough viable seeds for the next generation to sprout.
How Clover Survives the Off-Season
Perennial clover species, such as White Clover, survive cold or dry periods by entering a state of dormancy and relying on specialized storage structures. Above-ground runners called stolons creep along the soil surface, rooting at the nodes to form new plantlets. These stolons act as carbohydrate and protein reservoirs, allowing the plant to overwinter and regenerate fresh growth when temperatures rise in the spring.
The original central taproot of White Clover may eventually die, but the plant maintains its perennial status by forming adventitious roots at the nodes along the stolons. This continuous process of forming new, rooted sections allows the clover patch to persist and spread horizontally across the area. Short-lived annual species, in contrast, rely entirely on the hardiness of their seeds to bridge the gap between growing seasons.
Clover seeds possess a tough outer coating, allowing them to remain viable in the soil for several years before germination. This mechanism ensures that even if the parent plant of an annual or biennial variety dies, a reserve of seeds is present to sprout the following year. This strategy creates the impression that the same plant has returned, when it is actually a new generation emerging from the soil’s seed bank.
The Ecological Benefits of Clover
Clover is often encouraged due to its significant contribution to soil health and local ecosystems. The primary benefit is its ability to perform nitrogen fixation, converting atmospheric nitrogen gas into a usable form for plant growth. This process, achieved through a symbiotic relationship with Rhizobium bacteria on the roots, effectively enriches the soil and acts as a natural fertilizer for nearby plants.
Clover also provides several other ecological advantages:
- It exhibits a higher degree of drought tolerance compared to many common turfgrasses, remaining green during dry spells.
- Clover flowers serve as a consistent food source for various pollinators, including honey bees and bumblebees.
- The continuous production of nectar and pollen helps sustain local pollinator populations.
- The dense root and stolon systems help control soil erosion and improve overall soil structure.
Managing Clover in Your Lawn or Garden
Effective management of clover requires understanding whether the species present is an annual, biennial, or perennial. If the goal is to cultivate clover, such as for a lawn alternative or a cover crop, it is helpful to sow seeds when soil temperatures are reliably above 43°F (6°C), typically in the early spring or late summer. Encouraging clover growth involves minimizing the application of synthetic nitrogen fertilizer, as this encourages the grass to outcompete the clover.
For those aiming to reduce or eliminate clover, the approach must target its life cycle. Perennial White Clover, which spreads via stolons, requires more than just removing the top growth; the entire creeping stem and its rooted nodes must be removed to prevent regrowth. Conversely, controlling annual types like Crimson Clover focuses on preventing the plant from setting seed, which can be accomplished by mowing the flowers before they mature.
A long-term strategy for lawn areas involves encouraging a dense, healthy turf that can outcompete the clover. This includes mowing at a taller height, around 3 inches, to shade the low-growing clover and watering deeply but infrequently to promote deep grass roots. Since clover thrives in nitrogen-poor soil, applying a nitrogen-rich fertilizer can give the grass a competitive edge, naturally discouraging the clover’s growth.