Mustard is a fast-growing plant that offers tender, edible leaves with a pleasing peppery flavor, making it an excellent choice for a container garden. Its rapid maturation allows for multiple harvests in a single season, providing a continuous supply of fresh greens. Growing mustard in pots is an efficient method for maximizing small spaces like balconies, patios, or sunny windowsills. The container approach grants the gardener precise control over soil conditions and location, which is beneficial since mustard is a cool-season crop that struggles in summer heat.
Essential Preparation and Setup
The container must have effective drainage holes to prevent root saturation. A pot at least 6 to 8 inches deep and 12 inches wide is sufficient, though larger containers offer a more stable environment for moisture retention. The planting medium should be a high-quality, well-draining potting mix, not heavy garden soil, which compacts easily and impedes root growth. A blend of potting mix with added compost or well-rotted manure provides the necessary fertile, moisture-retentive base for lush leaf production.
Mustard seed varieties offer a range of flavors and leaf textures, which influences the final harvest. Varieties like ‘Green Wave’ and ‘Giant Curled’ are known for their frilly, more pungent leaves, while ‘Mizuna’ provides a milder flavor with deeply lobed foliage. ‘Giant Red’ or ‘Red Giant’ varieties introduce an attractive purple-tinged color to the container garden. Selecting a variety based on desired flavor and appearance is the first step, as all common types adapt well to container life.
Sowing Techniques for Container Planting
Mustard is a cool-season crop that thrives when planted in early spring or late summer, allowing it to mature before intense heat or hard freezes. The timing of sowing is flexible, and successive plantings every two to three weeks will ensure a continuous supply of young, tender leaves. For harvesting as greens, broadcast sowing is effective, where seeds are scattered freely across the soil surface.
If growing microgreens, scatter seeds about a half-inch apart, a density that encourages competition. For larger, mature plants, thin the seedlings to about 4 to 6 inches between plants once they emerge. Cover the seeds lightly with about a quarter-inch of potting mix or fine seed-starting medium. Immediately following sowing, water the soil gently with a fine spray to settle the seeds and ensure consistent moisture. Germination typically occurs within four to fourteen days in temperatures between 45°F and 75°F.
Ongoing Care and Environmental Needs
Mustard plants require a location that receives full sun to partial shade, needing a minimum of four to six hours of sunlight daily for healthy growth. The optimal temperature range is between 45°F and 75°F. Temperatures exceeding this upper limit can cause the leaves to become bitter and hasten bolting, the process where the plant prematurely initiates flowering. In warmer periods, providing light shade helps prevent this.
Consistent and even soil moisture is required for container-grown mustard, as potting mix dries out faster than garden soil. The soil must be kept continuously moist but never waterlogged, which leads to root rot. Water when the top inch of soil feels dry, preferring deep watering over shallow sprinkles. Since frequent watering leaches nutrients, apply a balanced, water-soluble fertilizer focused on nitrogen every three to four weeks.
Pest management in container mustard is generally simpler than in a garden bed, but common pests like aphids and flea beetles can still pose a threat. Aphids congregate on the underside of leaves and stems, sucking the plant’s sap, and can be treated with insecticidal soap or neem oil. Flea beetles create small, characteristic holes in the leaves, which can be prevented using physical barriers like floating row covers.
Harvesting for Greens Versus Seeds
The method of harvest depends on the goal: collecting edible leaves or gathering seeds. For greens, the first harvest can begin as early as three to four weeks after sowing, when the leaves are small and tender. The most common approach for a continuous yield is the “cut-and-come-again” method, where only the larger, outer leaves are snipped near the base, allowing the inner, smaller leaves to continue growing.
Alternatively, the entire head of greens can be cut with scissors about an inch or two above the soil line. The remaining stub will often regrow for a second, less vigorous harvest.
Harvesting for Seeds
Harvesting for seeds requires a different strategy, as the plant must be allowed to bolt, forming a tall flower stalk. After the yellow flowers fade, they develop into small, dry seed pods, called siliques.
The pods are ready for collection when they turn light brown and dry. The entire plant can then be cut and placed over a drop cloth or container to catch any seeds that shatter. To separate the seeds, the dried pods are rubbed between the hands or crushed to release the tiny, round mustard seeds.