Shiso (Perilla frutescens), also known as perilla, beefsteak plant, or Japanese basil, is a versatile herb cherished for its distinct flavor and vibrant foliage. It offers a unique culinary experience, often described as a blend of mint, basil, and cumin. This aromatic plant is relatively easy to cultivate, adding both beauty and flavor to your home garden.
Essential Growing Conditions
Shiso requires at least six hours of direct sunlight daily for robust growth and intense leaf coloration. While full sun is preferred, it tolerates partial shade, especially in regions with very hot summer afternoons, which helps prevent leaf scorch.
Shiso performs best in well-draining soil rich in organic matter. A slightly acidic to neutral pH (6.0-7.0) is optimal for nutrient uptake. Incorporating compost or well-rotted manure before planting improves soil structure, fertility, and root development.
Consistent moisture is important for healthy shiso. The soil should remain evenly moist but never waterlogged, as excessive wetness can lead to root rot. Water deeply when the top inch of soil feels dry, especially during dry spells.
Shiso prefers warm temperatures, thriving between 65°F and 75°F (18°C-24°C). It is sensitive to frost; protect or bring indoors if temperatures drop below 50°F (10°C). Moderate humidity is also beneficial for optimal growth.
Planting and Initial Care
Starting shiso from seed often requires cold stratification to improve germination. Place seeds in a moist paper towel inside a sealed plastic bag in the refrigerator for two weeks to mimic winter conditions and break dormancy. Sow seeds about a quarter-inch deep in seed-starting mix, typically in spring after the last frost.
Once seedlings develop a few true leaves, transplant them into larger pots or directly into the garden. Handle young plants carefully to avoid disturbing their delicate root systems. When transplanting, ensure proper spacing of 12 to 18 inches between plants.
Adequate spacing allows for good air circulation and prevents overcrowding as plants mature. After transplanting, provide a thorough initial watering to settle the soil around the roots. This watering is crucial for reducing transplant shock and helping the plant establish.
Ongoing Maintenance
Shiso benefits from regular feeding, especially if grown in containers or less fertile soil. Apply a balanced liquid fertilizer, diluted to half strength, every two to four weeks during the active growing season. For garden beds, a slow-release granular fertilizer or compost top dressing provides sustained nutrients.
Pinching back shiso’s growing tips is an effective technique to encourage bushier growth and prevent legginess. This promotes lateral branch development, leading to a more compact and productive plant. Regular pinching also delays flowering, extending leaf production.
Shiso can encounter common garden pests, such as aphids and slugs. Aphids can be dislodged with a strong water spray or treated with an insecticidal soap. Slugs can be managed with beer traps or diatomaceous earth around the base of the plants. Powdery mildew may appear in humid conditions; ensure good air circulation and avoid overhead watering to prevent this fungal issue.
Harvesting Shiso
Regularly harvesting shiso leaves encourages more foliage production throughout the growing season. Begin harvesting individual leaves once the plant has established and has at least six to eight true leaves. Select outer leaves first, allowing inner leaves to continue growing and maturing.
To promote continuous production, pinch off top sets of leaves or entire stems just above a leaf node. This stimulates new growth from leaf axils, providing a steady supply of fresh leaves. Avoid harvesting more than one-third of the plant at a time to prevent stressing it.
The best time to harvest shiso is in the morning after the dew has dried but before the heat of the day. Leaves harvested then have the most intense flavor and are crispest. Freshly picked shiso is best used immediately or stored in the refrigerator for a few days by wrapping in a damp paper towel and placing in a plastic bag.