Thyme in Zone 7B — Pacific Northwest

Thyme is a must-have herb in any Pacific Northwest garden. Its earthy flavor elevates everything from roasted vegetables to hearty stews, and it thrives in our mild summers and cool nights. Plus, the bees absolutely love its flowers! There's real satisfaction in snipping fresh thyme from your garden to use in the kitchen.

While we do face some challenges here—like our wet springs and the occasional bout of late blight—with a little planning, you can easily grow thyme successfully. Our long, mild fall extends the harvest window, and our 193-day growing season is plenty long enough to get a great yield from this hardy herb.

Starting thyme indoors gives you a head start, especially since it can be slow to get going from seed. If you're eager for an early harvest, sow seeds indoors from mid-February through early March, about eight weeks before you plan to transplant.

Use seed trays with a good seed-starting mix, and keep them consistently moist by bottom watering. Provide warmth and plenty of light—a grow light is especially helpful during our overcast spring days. Remember, our springs here tend to be slow, so patience is key.

Transplant your thyme seedlings outdoors from mid-April through mid-May, after the danger of hard frost has passed. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week.

Space your thyme plants 8-12 inches apart in a sunny spot with well-drained soil. Keep an eye on the weather forecast; late frosts can still occur in April, so be prepared to cover your young plants if needed. Honestly, though, buying starts from a local nursery is often the easiest way to go. It saves you a lot of time and gets you to harvest much faster.

Direct sowing thyme is possible, especially if you're not in a rush. Sow seeds directly into well-prepared soil from mid-April through early August. The soil needs to be at least 60°F for good germination, so waiting until late April or early May is generally best.

Prepare the soil by loosening it and removing any weeds. Scatter the tiny seeds thinly and lightly cover them with soil. Keep the soil consistently moist until the seedlings emerge. Thin the seedlings to 8-12 inches apart once they're large enough to handle.

Thyme is very drought-tolerant, which is great for our dry summer months in the Pacific Northwest. Overwatering is a much bigger concern than underwatering, as it can lead to root rot. During our wet springs, you may not need to water at all!

Once the weather warms up and the dry summer arrives, check the soil moisture regularly. Stick your finger about two inches deep into the soil; if it feels dry, it's time to water. Aim for about an inch of water per week during the driest periods. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our sometimes-humid conditions.

Signs of underwatering include wilting or drooping leaves, while yellowing leaves and a mushy stem indicate overwatering. A light layer of gravel mulch around the base of the plants can help improve drainage and prevent soil from splashing onto the leaves.

Thyme requires minimal pruning. The main goal is to prevent it from becoming too woody. After flowering, usually in late summer, cut back the stems by about one-third.

Be careful not to cut into the old, woody growth, as it may not regrow. This encourages fresh, new growth and keeps the plant compact and productive. In late October, before our first frost, you can give the plant a light trim to tidy it up for winter.

You can start harvesting thyme sprigs anytime from late June through early November, once the plants are established. The flavor is most intense just before the plant flowers.

To harvest, simply snip off stems with scissors or pruning shears. Avoid taking more than one-third of the plant at a time to ensure continued production. After harvesting, strip the leaves from the stems and use them fresh or dry them for later use. As our first frost approaches in late October, harvest any remaining thyme to dry or freeze for winter use.

Thyme is generally easy to grow, but two common problems in the Pacific Northwest are root rot from overwatering and fungal diseases.

Root Rot from Overwatering

• What it looks like: Yellowing leaves, wilting even when the soil is moist, and a mushy, brown stem at the base of the plant.
• What causes it: Excess moisture in the soil, which suffocates the roots and allows fungal pathogens to thrive. Our wet springs can exacerbate this issue.
• How to fix/prevent it: Ensure your thyme is planted in well-drained soil. Avoid overwatering, especially during rainy periods. Consider planting in raised beds or containers to improve drainage.

Fungal Diseases

• What it looks like: Powdery mildew, rust, or other fungal growth on the leaves and stems.
• What causes it: Humid conditions and poor air circulation, which can encourage fungal spores to develop. While our summers are dry, we can still get periods of humidity.
• How to fix/prevent it: Provide good air circulation by spacing plants adequately. Water at the base of the plant to avoid wetting the foliage. Remove any infected leaves promptly.

Pacific Northwest Specific Challenges: Our mild heat and dry-summer rainfall generally favor thyme, but our wet springs and occasional periods of humidity can create challenges. Pay close attention to watering practices and ensure good drainage to prevent root rot and fungal diseases.

Thyme makes a great companion plant in the Pacific Northwest garden. Rosemary, sage, and lavender all share similar growing requirements (full sun, well-drained soil) and help deter pests. Cabbage benefits from thyme's pest-repelling properties, while thyme can improve the flavor of strawberries. Plant thyme near tomatoes to attract beneficial insects. Avoid planting thyme near mint, as mint is very invasive and can quickly outcompete thyme for resources.