Valerian, botanically known as Valeriana officinalis, is a widely cultivated perennial herb prized for its tall, airy flower stalks and medicinal root. The plant forms a dense basal clump of foliage in its first year, typically reaching heights of three to five feet when it bolts to flower in its second season. The root contains compounds like valerenic acids, which are harvested for use in herbal remedies, primarily as a sleep aid. Cultivating Valerian successfully requires specific attention to its environmental needs and growth cycle to ensure a potent harvest. This guide provides the necessary steps to grow and process Valerian root for maximum yield and quality.
Site Selection and Soil Preparation
Choosing the right location for Valerian cultivation encourages deep root growth and avoids plant health problems. The herb thrives in conditions ranging from full sun to partial afternoon shade. Full sun is preferred in cooler climates to promote robust growth. In regions with intense summer heat, afternoon shade helps prevent stress and conserves soil moisture.
Valerian requires moist, fertile, and well-draining soil to prevent root rot. A rich, loamy soil texture with high organic matter content is ideal, mimicking the plant’s native moist meadow habitats. The soil pH should ideally be neutral to slightly acidic, ranging between 6.0 and 7.5.
Preparing the ground deeply is necessary because Valerian develops an extensive taproot system. Before planting, the soil should be loosened to a depth of at least 8 to 12 inches to allow the roots to penetrate easily. Incorporating two to four inches of aged compost or well-rotted manure will improve both the fertility and drainage of the planting bed.
Propagation Methods and Timing
Valerian can be started using two main methods: sowing seeds or dividing established root crowns. Propagating from fresh seed is common, but seeds have a short shelf life and lose viability quickly, so using current season seed is recommended. Seeds often require cold stratification, which mimics winter conditions, to break dormancy and improve germination rates.
Seeds can be sown indoors in early spring about four weeks before the last expected frost, or directly into the garden in mid to late spring. Since the seeds are very small and need light to germinate, they should be surface-sown and pressed lightly into the soil. Starting seeds indoors allows for greater control over moisture and temperature, producing stronger seedlings ready for transplanting once they reach five or six inches tall.
The fastest way to establish new plants is through root division, separating the rhizomes of a mature plant. Division is best performed in the fall after the foliage has died back or in the very early spring before new growth begins. Each division must have a healthy section of the crown and its own set of roots to ensure successful establishment. Dividing the clumps every few years also helps rejuvenate the plant and prevent overcrowding.
Ongoing Care and Growth Management
Once Valerian plants are established, consistent moisture is important, as the herb prefers evenly damp soil during active growth and hot weather. Watering should be deep and regular, ensuring the soil remains moist but never waterlogged to protect the root system. Applying a two to three-inch layer of organic mulch, such as straw or shredded leaves, helps maintain soil moisture, suppress weeds, and keep the roots cool.
Fertilization requirements are minimal, as overfeeding, particularly with nitrogen, can lead to excessive foliage growth at the expense of root development. A single application of a granular slow-release fertilizer in early spring is often sufficient. Alternatively, working aged compost into the soil before planting provides a steady release of nutrients throughout the season.
Valerian is a tall plant, with flower stalks potentially reaching five feet or more, requiring physical support to prevent stems from bending over. Staking tall varieties or planting them in a sheltered location keeps the stalks upright and protects the plant from wind damage. Since Valerian self-seeds readily, removing the flower heads after they fade will prevent the plant from spreading throughout the garden.
Harvesting and Drying the Root
Timing is the primary factor for maximizing the concentration of medicinal compounds in the root. The roots should not be dug until the plant has completed at least two full growing seasons. The optimal time to harvest is in the fall of the second year, typically after the first frost, when the plant’s energy has been fully drawn down into the root system for winter dormancy.
To harvest, the entire plant is dug up, often requiring a garden fork to loosen the soil and retrieve the deep taproots. Watering the area deeply the day before digging softens the soil and makes extraction easier. Once harvested, the roots and rhizomes must be thoroughly cleaned to remove all soil and debris, often involving careful scrubbing.
After cleaning, the roots need to be dried quickly and efficiently to preserve active compounds like valerenic acid. Drying should occur in a well-ventilated area using low heat, ideally below 100°F (40°C), as high temperatures degrade the volatile oils. The roots release a strong, distinctive odor as they dry, so outdoor drying or a dedicated space is highly recommended. Larger roots should be cut or chopped to speed up drying and ensure thorough moisture removal. Once completely dry, the roots should be stored in an airtight container away from light and heat to maintain potency.