Arugula, also known as rocket, is a popular, peppery-flavored leafy green used in salads. Its rapid growth cycle and compact habit make it ideal for cultivation in small spaces or urban gardens. Growing arugula in containers allows for a quick turnaround from seed to harvest.
Container and Soil Preparation
A container with a minimum depth of six inches is recommended to ensure adequate space for root development and moisture retention. Proper drainage is mandatory, so the container must have holes in the bottom to prevent the growing medium from becoming waterlogged and causing root rot.
The container material also influences moisture levels; terracotta pots wick away water faster than plastic or glazed ceramic, requiring more frequent checks. The growing medium must be a high-quality, lightweight potting mix, which promotes aeration and water flow. Traditional garden soil should be avoided as it compacts easily in pots, restricting root growth and impeding drainage. Mixing in aged compost or perlite can further enhance the soil structure and nutrient profile.
Planting and Initial Setup
Once the container is filled, sow the arugula seeds very shallowly, covering them with no more than a quarter inch of soil. Seeds can be sown densely, as they germinate quickly, typically within four to eight days under optimal conditions. The ideal temperature range for germination is between 40°F and 65°F (4°C to 18°C), making it a suitable crop for early spring or fall planting.
Immediately after sowing, place the container in a location that receives bright light to encourage robust seedling development. Once the seedlings develop their first set of true leaves, they must be thinned to their final spacing. Gently remove the weaker seedlings until the remaining plants are spaced approximately two to four inches apart. This ensures adequate air circulation and space for the mature leaves to develop fully.
Ongoing Care and Maintenance
Managing water levels is the most significant challenge when growing leafy greens in containers, as the limited soil volume dries out rapidly. Check the moisture level daily by inserting a finger about an inch into the potting mix; if it feels dry, water immediately until the water flows freely from the drainage holes. Consistent moisture is necessary because allowing the soil to dry out stresses the plant, which can prematurely trigger the bolting process.
Arugula thrives in bright light, which encourages fast, succulent growth, but it is highly sensitive to intense heat. Temperatures consistently above 75°F (24°C) often cause the plant to “bolt,” producing a tall central flower stalk. This process redirects the plant’s energy from leaf production to seed production, causing the leaves to develop a sharp, bitter flavor. To mitigate heat stress, move the container to a location that receives partial afternoon shade during the hottest parts of the day.
Since container potting mixes contain finite nutrients that are quickly leached out with frequent watering, supplemental feeding is necessary for sustained production. Start feeding the plants with a diluted, balanced liquid fertilizer, such as a 5-5-5 formula, about two weeks after germination. Applying this liquid feed every three to four weeks helps replenish the nitrogen needed for vigorous leaf growth.
Routinely inspect plants for common container pests like flea beetles, which create small, characteristic shot-hole patterns in the leaves. A simple, non-chemical approach involves monitoring the undersides of the leaves and gently wiping away any small insects that are found. Ensuring good air circulation around the container also helps discourage fungal issues.
Harvesting Techniques
Arugula is ready for its first harvest about three to four weeks after planting, when the outer leaves reach a usable size of approximately four to six inches long. The most efficient method for container growing is the “cut-and-come-again” technique, which allows for multiple harvests from the same plant.
To execute this, use clean scissors or shears to snip the outer leaves near the base of the plant, about an inch above the soil line. Always leave the inner, smaller leaves and the central growing point intact, which enables the plant to regenerate new foliage quickly. Continuous harvesting encourages the plant to produce more leaves and delays the onset of bolting, extending the period of tender leaf production. If the plant does eventually bolt, the leaves will become significantly spicier and tougher.