Arugula, also known as rocket, is a fast-growing leafy green celebrated for its distinct peppery and slightly nutty flavor. Young, tender leaves can be ready for harvest in as little as three to four weeks from sowing. Arugula thrives in cool temperatures, making the precise timing of planting the most important factor for ensuring a long harvest of mild, flavorful leaves.
Early Spring Timing and Methods
The best time to plant arugula in spring is as soon as the soil becomes workable, often several weeks before the average last frost date. Seeds can germinate when the soil is as cool as 40°F, allowing gardeners to start crops early and extend the cool-weather harvest before summer heat arrives.
Direct sowing is the recommended method, as arugula seedlings transplant poorly due to their shallow root system. Plant seeds about one-quarter inch deep, lightly covering them with soil. For a dense harvest of baby greens, sow seeds closely, about one inch apart, and thin them as they grow. While seedlings can withstand a light frost, a row cover can ensure a vigorous start to the season.
Planning for the Fall Harvest
The fall season often produces the most flavorful and tender arugula leaves. The gradual cooling of autumn provides a more stable, extended period of ideal growth temperatures than the unpredictable warming of spring. Fall planting requires calculating the timing to ensure the crop matures before the hard freeze.
To determine the final sowing date, count back 4 to 6 weeks from your region’s average first fall frost date. This timing allows plants to reach a harvestable size before sustained freezing temperatures. Sowing seeds in late summer or early fall capitalizes on cooling soil temperatures that minimize heat stress. Late-season crops can be protected with cold frames or frost cloth, extending the harvest well into the winter months.
Avoiding Bolting and Heat Stress
Bolting is the premature growth of a tall flower stalk for seed production. This shift is primarily triggered by high temperatures, typically above 75°F, or by the lengthening days of summer. Once the plant bolts, its energy diverts from leaf production to reproduction.
The most noticeable consequence of bolting is a change in leaf flavor, which quickly becomes intensely bitter and overly peppery. To prevent this, cease planting once the weather begins to warm significantly. Mitigation techniques, such as planting in a location that receives partial afternoon shade, can help delay bolting. Maintaining consistently moist soil also helps keep the plants cool and reduces the stress that encourages flowering.
Maximizing Yield with Succession Sowing
Arugula’s rapid growth makes it an excellent candidate for succession sowing, a technique that ensures a steady supply of fresh leaves. Since baby greens are ready for cutting in about 20 to 30 days, a single large planting results in a glut of leaves followed by a period with none. Succession sowing avoids this feast-or-famine cycle.
To achieve a continuous yield, plant a small batch of seeds every one to two weeks throughout the cool seasons of spring and fall. This staggered approach means that as one planting begins to mature and potentially bolt, the next succession of plants is reaching its peak tenderness. Planting small amounts frequently guarantees a steady flow of young, mild leaves rather than a single, overwhelming harvest.