Starting Herb Seeds: A Thyme Garden Guide

Growing herbs from seed is one of the most rewarding parts of gardening—and one of the best ways to build a resilient, flavorful home apothecary or kitchen garden. At The Thyme Garden in Alsea, Oregon, we’ve spent decades growing, harvesting, and saving herb seeds adapted to our Pacific Northwest climate. Each herb seed carries its own rhythms, preferences, and personality, and understanding those differences sets you up for success.

Planting seeds in seedling trays in January

Why Herb Seed Variety Matters

Not all seeds want the same treatment. Some need light to germinate, others need darkness. Some thrive when sown directly in the soil, while others benefit from a protected indoor start. Paying attention to seed type helps improve germination rates, plant health, and overall garden success.

Choosing the Right Herb Seeds

Not all herbs are equally easy to start from seed. Some varieties germinate quickly and grow well indoors, while others prefer direct sowing outdoors or need special treatment.

• Easy herbs for beginners: Basil, cilantro, parsley, dill, and chamomile.

• Moderate difficulty: Rosemary, sage, oregano, and mint.

• Challenging herbs: Lavender and thyme often require patience and specific conditions.

  
  

Select seeds from reputable suppliers to ensure good germination rates. Check the seed packet for information on planting depth, germination time, and temperature preferences.

Annual vs. Perennial Herb Seeds

Annuals complete their life cycle in one season. These seeds usually germinate quickly and are ideal for beginners.

• Examples: basil, dill, cilantro, calendula

• When to start: Indoors in early spring or direct-sown once soil warms

• Tips: Sow herbs like dill and cilantro successively every few weeks for continuous harvests

Perennials take longer to establish but return year after year.

• Examples: thyme, sage, lavender, lemon balm, oregano, echinacea

• When to start: Indoors late winter to early spring, or direct-sown in fall

• Tips: Be patient—many perennials focus on root growth their first year

As you go you may notice some herb seedlings get much bigger than others. If you can, group these biggies together.

Small Herb Seeds vs. Large Herb Seeds

Small seeds need special care and a gentle touch.

• Examples: thyme, oregano, chamomile, savory, yarrow

• How to sow: Press lightly onto the soil surface or cover very thinly

• Key need: Light for germination (check individual varieties)

Large seeds are easier to handle and often sprout more reliably.

• Examples: cilantro, dill, fennel

• How to sow: Plant deeper—about twice the seed’s size

• Key need: Even moisture, especially during early growth

Basil is an easy to grow herb with great germination and endless variation!

Preparing the Growing Medium

Herbs need a light, well-draining seed-starting mix rather than regular garden soil. Seed-starting mixes are usually sterile, fine-textured, and free of weed seeds or diseases.

• Use a commercial seed-starting mix or make your own by combining peat moss or coconut coir with perlite or vermiculite.

• Moisten the mix before filling your seed trays or pots. It should be damp but not soggy.

• Avoid compacting the soil to allow easy root growth and air circulation.

  
  

Sowing Seeds Correctly

Proper sowing technique improves germination success.

• For starting seeds indoors in pots, fill containers with the prepared mix, leaving about half an inch of space at the top.

• For seedling trays, spread seedling soil mix evenly over the tray, filling in gaps and making sure there is an even amount of soil all the way to the edges. Press soil gently from the top with another tray to ensure even soil distribution.

• Plant seeds at the depth recommended on the packet. A general rule is to plant seeds twice as deep as their size.

• For very small seeds like basil or thyme, sprinkle them on the surface and lightly press them into the soil without covering too deeply.

• Space seeds evenly to avoid overcrowding.

• Mist the surface gently with water to settle the seeds.

The smaller the seed, the harder it is to space them evenly.

Providing Ideal Germination Conditions

Herb seeds need warmth, moisture, and light to sprout.

• Temperature: Most herb seeds germinate best between 65°F and 75°F (18°C to 24°C). Use a heat mat if your home is cool.

• Moisture: Keep the soil consistently moist but not waterlogged. Covering the containers with plastic wrap or a humidity dome helps retain moisture.

• Light: Some seeds need light to germinate (e.g., thyme), so avoid covering them with soil. Once seeds sprout, place them in a bright spot or under grow lights for 12-16 hours daily.

  
  

Check daily for moisture and remove covers once seedlings emerge to prevent mold.

Thinning Seedlings

Once seedlings develop their first true leaves, thinning is necessary to give each plant enough space.

• Use small scissors to snip weaker seedlings at soil level rather than pulling them out, which can disturb roots.

• Leave the strongest seedlings spaced according to the herb’s mature size (usually 2-4 inches apart).

• Thinning improves airflow and reduces competition for nutrients.

As hard as it is to do, you must thin your plants for the best outcome. Use very small sharp scissors. If it's basil or something yummy, save the shoots to add to dinner!

Transplanting Seedlings

When seedlings grow 2-3 inches tall and have several sets of leaves, they are ready to move to larger pots or outdoors.

• Harden off seedlings by gradually exposing them to outdoor conditions over 7-10 days.

• Transplant carefully to avoid root damage.

• Use well-draining soil and water thoroughly after transplanting.

When your seedlings have their true leaves, you can pot them up into larger pots. Pack potting soil loosely in the pot, make a hole a little larger than your plug, and gently transfer. We use small tongs for this step. Press soil gently around the plug and water in around the plant, avoiding the actual plant. We add liquid B-vitamin to our water at a ration of 1/2 cup to 5 gallons.

Common Challenges and How to Avoid Them

• Damping off: A fungal disease causing seedlings to collapse. Prevent by using sterile soil, avoiding overwatering, and ensuring good air circulation.

• Leggy seedlings: Caused by insufficient light. Use grow lights or place seedlings in a sunny window.

• Poor germination: Check seed viability, planting depth, and temperature. Some seeds may need soaking or scarification.

Tips for Success

• Label your seed trays to keep track of different herbs. Use a pencil as pens will wear off.

• Start seeds indoors 6-8 weeks before the last frost date in your area.

• Use a spray bottle for watering to avoid disturbing seeds.

• Rotate trays regularly for even light exposure.

• Keep a journal to note germination times and growth progress.

  
  

Growing herbs from seed is a fulfilling project that connects you to your food and nature. With patience and attention to detail, you can enjoy fresh herbs year-round, enhancing your cooking and home environment.