Thyme (Thymus vulgaris) is a popular, versatile herb. Propagation allows gardeners to expand their collection or rejuvenate older plants.
Why Propagate Thyme
Propagating thyme is cost-effective and allows gardeners to increase their plant stock. It also helps maintain specific, desirable varieties not readily available for purchase. This method rejuvenates older, woody plants, ensuring a continuous supply of fresh leaves.
Thyme Propagation Methods
Propagating from Cuttings
Propagating thyme from cuttings produces new plants genetically identical to the parent. Select healthy, non-woody shoots from a mature plant, ideally in late spring to early summer before flowering. Use sharp, clean scissors or pruners to take 4 to 6-inch cuttings, cutting just below a leaf node. Remove leaves from the lower two-thirds of each cutting to encourage root development.
Root thyme cuttings in either water or a well-draining soil mix. For water rooting, place prepared cuttings in a glass of fresh water, submerging only the leafless portion. Place the glass in a warm location with indirect sunlight, changing the water every few days. Roots form within 4 to 6 weeks.
To root in soil, fill small pots with a well-draining soil mix. Make a hole with a pencil and gently insert the cutting, firming soil around the base. Maintain consistent moisture, avoiding overwatering. Keep pots in a warm, bright spot away from direct sunlight, at 20-25°C. Roots develop within 6 to 8 weeks.
Propagating from Seeds
Starting thyme from seeds can be slower and result in less consistent plant characteristics than other methods. Thyme seeds are tiny and require light for germination. Sow them indoors in late February or early spring, 8-10 weeks before the last frost. Use a propagation tray filled with well-draining seed-starting compost.
Scatter seeds evenly over the moistened compost surface and gently press them down; avoid deep covering. Cover the tray with a clear film or plastic lid and place it in a warm, well-lit area, avoiding direct sunlight. Germination takes 2 to 4 weeks at 16-21°C. Keep compost moist and ventilate daily. Once seedlings appear, remove the cover. When they develop a few true leaves, transplant them into larger pots.
Propagating by Division
Propagating thyme by division rejuvenates mature, woody plants, typically 3 to 4 years old. Perform this method in spring as new growth emerges or in early fall. Carefully dig up the entire thyme plant, including its root ball.
Once out of the ground, remove any diseased sections and the old, woody central part. Using a clean, sharp knife or spade, divide the remaining healthy portions into smaller sections, ensuring each has a root system. Replant divisions approximately 30 cm apart in their new locations and water thoroughly.
Propagating by Layering
Layering is a simple propagation method where a stem roots while still attached to the parent plant. This technique is effective for thyme, as its stems often root naturally when touching soil. Select a healthy, flexible, non-woody stem from the parent plant.
Gently bend the stem to the ground, ensuring a node makes contact with the soil. You can lightly wound the stem’s underside at this point to encourage rooting, though it is not always necessary. Secure the stem firmly to the soil using a U-shaped wire pin, a small rock, or by lightly burying a section. Keep the soil consistently moist. Roots will form at the buried node, typically within 3 to 4 months. Once a substantial root system develops, sever the new plant from the parent and transplant.
Caring for New Thyme Plants
After successful propagation, new thyme plants require care for healthy establishment. Immediately after rooting or transplanting, water thoroughly to settle soil and minimize transplant shock. Thyme prefers well-draining soil and full sun, so ensure the location receives at least 6-8 hours of direct sunlight daily.
Newly established plants benefit from consistent moisture, but avoid overwatering. Allow the top inch of soil to dry out between waterings. If started indoors, gradually acclimate them to outdoor conditions by hardening off, exposing them to increasing outdoor periods over 7-14 days. Once established, thyme plants are drought-tolerant.
Common Propagation Challenges
Gardeners may encounter challenges during thyme propagation, but solutions exist. If cuttings fail to root, it is due to overly woody stems, insufficient moisture, or improper cutting technique. Select soft, new growth and maintain consistent humidity. Overwatering causes cuttings to rot, so provide good drainage and allow the rooting medium to dry slightly between waterings.
Seedlings suffer from damping-off, a fungal disease causing young plants to collapse at the soil line. This results from excessive moisture, poor air circulation, or contaminated soil. To prevent this, use sterile seed-starting mix, ensure good airflow, and avoid overwatering. Transplant shock, characterized by wilting or yellowing leaves after moving, occurs due to root disturbance or sudden environmental changes. To mitigate, water plants well before and after transplanting, and harden off seedlings gradually before moving them outdoors permanently.