Clover is a popular choice for gardeners seeking a nitrogen-fixing cover crop or a low-maintenance lawn alternative. While planting clover in the summer is technically possible, it presents significant difficulties and carries a much higher risk of failure compared to other seasons. Successful establishment during this period requires meticulous preparation and intensive post-sowing care to counteract environmental extremes.
Environmental Risks of Summer Planting
Clover generally thrives when temperatures remain between 50°F and 85°F, conditions often exceeded during peak summer. High heat stress is the primary challenge, severely limiting successful seed germination. Clover seeds prefer a consistent soil temperature around 68°F (20°C) for optimal sprouting, a threshold easily surpassed by direct summer sun.
Another major difficulty is maintaining adequate moisture for the shallowly sown seeds. Clover requires the top layer of soil to remain consistently damp for the 7 to 14 days needed for germination. Summer heat causes rapid moisture evaporation, leading to desiccation and failure of young seedlings before their root systems can take hold.
The season also brings intensified competition from aggressive summer weeds. These weeds are adapted to high heat and can quickly outgrow and shade the newly emerged clover sprouts. Young clover growth is susceptible to sun scorch and stress before it develops the taproots that provide drought tolerance.
Optimizing Soil and Seed Preparation
Mitigating the risks of summer planting begins with thorough preparation of the seedbed to eliminate competitors. The planting area must be cleared of all existing vegetation, either by tilling or applying an appropriate herbicide, to prevent weeds from overwhelming the sprouts. Loosening the top layer of soil is necessary to ensure excellent seed-to-soil contact, a foundational requirement for successful germination.
Clover performs best in soil pH between 6.0 and 7.0, so a soil test should determine if lime is necessary to adjust acidity. Seed treatment can further increase the chances of summer success. Clover seed benefits from scarification or pre-soaking to break down its hard shell and accelerate germination.
It is recommended that the seed be inoculated with the specific strain of Rhizobium bacteria before sowing. This bacteria is necessary for the clover to form root nodules and fix atmospheric nitrogen, bolstering the plant’s health. Fresh inoculation is important when clover is introduced to a location for the first time, even if the purchased seed was pre-inoculated.
After preparing the seed and soil, the seed should be broadcast and covered very lightly, to a depth of no more than 1/8 to 1/4 inch, since the seeds require light to sprout. The most time-consuming part of summer planting is the precise irrigation strategy. Instead of deep, infrequent soaking, the area requires light, frequent misting multiple times daily to keep the surface consistently moist. Timing the planting just before a predicted gentle rain or using temporary shade cloth can provide a buffer against immediate heat shock.
Alternative Planting Seasons
For those seeking a higher probability of success with less intensive management, planting clover during milder seasons is recommended. The two most favorable planting windows are early spring and late summer to early fall. These seasons naturally provide the moderate temperatures and consistent moisture required for initial establishment.
Early spring planting, following the final frost, allows the clover to germinate and establish its root system during cool and moist conditions. This head start permits the plant to build resilience before the intense heat of summer arrives.
Planting in late summer, typically between late August and early September, is equally effective. This timing allows seedlings to utilize the moderate temperatures and increased natural rainfall of autumn. The clover dedicates the fall season to developing a strong, deep root structure before entering winter dormancy, ensuring a vigorous start the following spring.