White clover (Trifolium repens) is valued in lawns and pastures for its durability and nitrogen-fixing capabilities. When summer heat arrives, the plant’s leaves shrivel and growth slows, leading many to question if it has died. In most cases, white clover does not die; instead, it employs a survival strategy known as summer dormancy. This temporary shutdown conserves energy and moisture, keeping the main structures alive so the plant can reappear when cooler, wetter conditions return in the fall.
Clover’s Response to Heat and Drought
Perennial clover prevents death during hot, dry periods by entering summer dormancy. This physiological choice significantly reduces above-ground growth to minimize water loss through transpiration. The plant conserves internal resources by allowing leaves and stems to wither, which creates the appearance of death.
Survival relies on the plant’s root system and specialized horizontal stems called stolons. The stolons creep along the soil surface and contain nodes, which are the plant’s growing points. Even if the entire canopy of leaves and flowers dies back due to heat and lack of water, the stolons and the central crown remain living, protected close to the cooler soil.
Although white clover has a relatively shallow root system, it provides a lifeline by extracting residual moisture to sustain the dormant stolons. The plant sacrifices its visible parts to protect the vegetative reproductive structures. This mechanism ensures that the clover can rapidly sprout new leaves and stems as soon as adequate rainfall and moderate temperatures return.
Species Matters: Annual Versus Perennial Clover
The fate of clover in summer depends entirely on its species, which fall into two distinct life cycles. Perennial clovers, like white clover (Trifolium repens), live for multiple years. Their programming allows them to enter dormancy, a necessary survival tactic to bridge the gap between growing seasons.
Annual clovers, such as crimson clover (Trifolium incarnatum) or subterranean clover, follow a different life cycle. These varieties are programmed to complete their entire life cycle—germination, growth, flowering, and setting seed—within a single year. When the heat of summer arrives, these annual clovers genuinely die after producing their seeds. The stand is maintained only if the seeds successfully germinate and establish new plants in the following season.
Summer Care for Healthy Clover
To encourage perennial clover to thrive through the summer and minimize the period of dormancy, maintenance adjustments are necessary. A primary step involves adjusting the lawnmower height, as a taller canopy provides significant benefits. Mowing the clover and surrounding grass at a higher setting, such as three to three-and-a-half inches, helps shade the soil surface. This shading keeps the stolons and the soil cooler, reducing moisture evaporation and mitigating heat stress.
Water management is another important factor for preventing deep dormancy. Although clover is generally drought-tolerant once established, providing approximately one inch of water per week during extended dry spells will keep the plants actively growing. It is better to water deeply and infrequently, as this encourages the root system to grow deeper into the soil, rather than promoting surface roots with shallow, frequent watering.
Avoid using synthetic weed killers during the hottest part of the year when maintaining a clover lawn. Many broadleaf herbicides designed for traditional grass lawns will also damage or eliminate clover. Chemical application during high summer temperatures increases stress on the plant, potentially forcing it into dormancy more quickly than heat alone.