Arugula is a fast-growing, cool-weather leafy green prized for its peppery flavor. Proper spacing is the most important factor for success when growing this crop. Adequate distance maximizes light exposure and air circulation, which prevents premature bolting and minimizes disease risk. Managing plant density ensures high-quality leaf production and prevents bitterness or rapid flowering.
Determining the Ideal Spacing
The ideal spacing depends on whether you prefer small “baby greens” or large, mature leaves. For baby arugula, which is harvested when leaves are small and tender, aim for one inch between plants. This dense planting allows for high-yield production in a small area. It is often achieved by scattering seeds in a wide band about two to four inches across.
To grow large, fully mature arugula leaves, plants need substantial room to reach their full size. The final spacing should be four to six inches between individual plants within a row. This wider spacing ensures plants receive enough light and nutrients to develop large, mild-flavored leaves. When planting in traditional rows, separate rows by twelve to eighteen inches to allow for easy access and robust air flow. Sufficient space reduces plant stress, which triggers bitterness and bolting.
Achieving Proper Spacing Through Thinning
Since arugula is typically direct-sown by scattering seeds, thinning the dense cluster of seedlings is mandatory to achieve the final spacing. The first thinning should occur once seedlings are about one inch tall and have developed their first set of true leaves. At this stage, remove the weakest or most crowded seedlings. Ensure the remaining plants have at least an inch or two of space.
The most effective thinning technique is to use small scissors or snips to cut unwanted seedlings at the soil line. Pulling a seedling can disturb the shallow root systems of neighboring plants, causing shock and growth setback. Snipping the stem leaves the removed plant’s roots in the soil to decompose. This avoids disrupting the roots of the plants you intend to keep.
Thinning is often done in stages, progressively increasing the distance between remaining plants as they grow. The removed seedlings are edible and can be used as nutritious microgreens or baby greens. Continue this gradual removal until plants are spaced at their final distance of four to six inches apart. This systematic approach minimizes competition for resources and ensures the long-term health of the crop.
Staggered Planting for Continuous Harvest
Arugula’s rapid growth cycle and tendency to bolt quickly make staggered planting necessary for a steady supply. To maintain a continuous harvest of tender, mild leaves, sow a new batch of seeds every two to three weeks during the cool growing season. This method, known as succession planting, prevents the entire crop from maturing and bolting simultaneously.
It is more efficient to plant in small, dedicated blocks or short rows rather than one long row. Each block represents a separate planting date. This ensures that when the earliest batch slows production, the next section is ready for harvest. Continue this schedule until temperatures rise significantly in summer or until two to three weeks before the first anticipated fall frost.