Thyme in Zone 7A — Pacific Northwest

Thyme is a fantastic addition to any Pacific Northwest garden. Its aromatic leaves add a burst of flavor to your cooking, especially those cool-night-enhanced summer dishes. Plus, it's a beautiful, low-maintenance ground cover that attracts pollinators. Growing your own thyme is incredibly rewarding.

Our mild summers and wet springs here in Zone 7A can present some challenges, but with careful timing, you can easily grow thyme. We have a 183-day growing season, which gives you plenty of time to get a good harvest. Just be mindful of our spring soil temperatures.

Starting thyme indoors in our region is optional, but it can give you a head start. If you want to get a jump on the season, start your seeds indoors from mid-February through early March, about eight weeks before you plan to transplant them.

Use seed trays with a good seed-starting mix. Keep them warm (a heat mat helps) and provide plenty of light, especially since our overcast spring days can be dim. Bottom watering is a great way to keep the soil evenly moist without overwatering the delicate seedlings.

Transplanting thyme outdoors is best done from mid-April through mid-May, once the soil has warmed up a bit. Before transplanting, harden off your seedlings 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, as we can still get some unexpected cool snaps and even a late frost during this time. If you're impatient, buying starts from a local nursery can save you a whole season of waiting, as thyme is very slow to grow from seed.

Direct sowing thyme is definitely possible in the Pacific Northwest, especially if you're not in a rush. Sow seeds outdoors from mid-April through late July.

Make sure the soil is well-prepared and has warmed up sufficiently, as thyme seeds need warmth to germinate. Lightly cover the seeds with soil and keep them consistently moist until they sprout. Thin seedlings to 8-12 inches apart once they're established. Direct sowing is generally less successful than transplanting, but it's a fine option if you're patient.

Thyme thrives on neglect when it comes to watering, which makes it perfect for our dry summer months in the Pacific Northwest. Once established, thyme is very drought-tolerant and prefers well-drained soil. Overwatering is a much bigger concern than underwatering in our climate.

During our wet springs, you likely won't need to water thyme at all. Once the dry summer months arrive, check the soil before watering. Stick your finger about two inches deep; if it's dry, it's time to water. Aim for about 1 inch of water per week during dry spells. Water at the base of the plant to avoid wetting the foliage, which can encourage fungal diseases in our region. Yellowing leaves are a sign of overwatering, while drooping leaves indicate underwatering. A light mulch of gravel or pea gravel can help improve drainage and keep the soil surface dry.

Thyme requires minimal pruning, which is great for busy gardeners. After flowering, usually in mid-summer, cut back the stems by about one-third to prevent the plant from becoming woody.

Avoid cutting into the old, woody growth, as thyme doesn't always regrow well from there. In late fall, before our first frosts arrive around mid-October, you can give your thyme plant a light trim to tidy it up for the winter.

You can start harvesting thyme from late June through late October in the Pacific Northwest, about 70 days after planting. The best flavor comes just before the plant flowers.

To harvest, simply snip off sprigs as needed. Then strip the leaves from the stems. Regular harvesting encourages the plant to produce more growth, so don't be shy. As our first frosts approach in mid-October, harvest any remaining thyme to dry or freeze for later 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, and mushy stems, especially near the base of the plant.
• What causes it: Soggy soil due to overwatering or poor drainage. Our wet springs can exacerbate this issue.
• How to fix/prevent it: Plant thyme in well-drained soil. Water sparingly, only when the top inch or two of soil is dry. Improve drainage by adding gravel to the planting hole.

Fungal Diseases

• What it looks like: Powdery mildew or other fungal growth on the leaves.
• What causes it: Excessive moisture and humidity, especially during our dry summer months when we might be tempted to overwater.
• How to fix/prevent it: Ensure good air circulation around the plants. Water at the base of the plant to avoid wetting the foliage. Use a fungicide if necessary.

Pacific Northwest Specific Challenges: Our mild heat and dry-summer rainfall patterns mean that overwatering is a more significant threat to thyme than underwatering. Focus on providing excellent drainage and watering sparingly, especially during our wet springs.

Thyme makes a wonderful companion plant for several vegetables and herbs in the Pacific Northwest garden. Rosemary, sage, and lavender are excellent companions because they share similar growing requirements and attract beneficial insects. Cabbage benefits from thyme's ability to repel cabbage moths. Strawberry thrives alongside thyme as it deters slugs. Tomato plants benefit from thyme's pest-repelling properties. Avoid planting thyme near mint, as mint is aggressive and will quickly outcompete thyme for resources.