How To Start Thyme Seeds Indoors (Plus Growing Tips)

Thyme is my personal favorite culinary herb. The aroma is sweet and subtle, perfect for flavoring hearty soups and stews, or for infusing into butters and sauces. Thankfully, thyme is also easy to grow from seed.

There are many types of thyme, from German thyme to lemon thyme to creeping ground cover types. However, starting from seed is essentially identical for any variety. Having fresh herbs interplanted with our vegetable garden is a must for us, and thyme is a staple.

Thyme seeds are very small, so there is a bit of technique required for proper germination. However, with our easy steps you’ll have healthy new plants growing in your herb garden in no time!

Thyme seedlings sprouts in 6 cell trays
Thyme seedlings.

How To Start Thyme Seeds Indoors

Before getting to the planting process, you’ll want to make sure you have everything you need. I like to start thyme in 6-cell trays with a good seed starter mix. The tiny seeds benefit from the fine texture of seed starter soil rather than normal potting mix or garden soil.

Also, I highly recommend a spray bottle for keeping your seeds moist, along with a humidity dome. Lastly, be sure to start your thyme seeds at the right time, ideally about 6 weeks before your last frost date.

With everything in hand, it’s time to plant!

  1. Fill containers with seed starting mix. Start by pre-moistening your seed starter mix or potting soil. Add water and mix thoroughly until it is damp, but not soaking wet. Add the prepared mix to your seed starting trays and compress lightly until about 1/4″ from the top.
  2. Drop 2-4 seeds into each cell. Thyme seeds are tiny! I like to plant at least 2 seeds per cell to ensure at least 1 germinates, but feel free to add a few more for insurance. Don’t bury the seeds. Instead, gently press them onto the surface, leaving them on top of the soil. Check your fingers afterwards to make sure the seeds aren’t stuck to them!
  3. Gently mist surface of soil and seeds. With your seeds planted, gently spritz the soil with water. Make sure the seeds are well-moistened and are making good contact with the soil media.
  4. Cover with a humidity dome and keep warm. I like to use a humidity dome to keep the air humid and prevent too much evaporation. The ideal temperature for germinating thyme seeds is around 65-70°F. Unless you are starting your seeds in a cold location, there is no need to apply heat to keep them warm. Fresh thyme seeds should germinate within 1-2 weeks.

The steps to starting thyme seeds indoors are simple, but there are a few important things to keep in mind. Here are some tips for successfully germinating thyme seeds:

  • Keep the seeds moist until they sprout. If the seeds dry out before they sprout, they may fail to germinate. To prevent this, spritz the surface of the soil if it looks even slightly dry. Don’t spritz too strongly, as this may cause the seeds to shift or become buried in the soil.
  • Fan out the trays daily to keep the air fresh. While this isn’t critical, it is a good idea to keep the air inside your humidity dome fresh. I like to open the covering once a day to fan out the trays and keep the air from becoming too stale.
  • Use fresh seed. If you are using older seeds, your germination rate is likely to decrease. We recommend buying new seeds at the beginning of each season in late winter or early spring.
Thyme seedlings sprouts in 6 cell trays overhead
Thyme seedlings are very small to start. After they grow to about 1″ tall, thin to 1 plant per cell.

​These same principles apply to almost any seed variety. The main difference here is that thyme seeds are smaller than average, making them more tricky to germinate.

But they will germinate, and usually within 1 week of planting. Sprouts are also very small, and the seedlings will soon require light fertilizing to grow into strong young plants.

Growing Thyme In The Garden

Thyme can be grown in a wide variety of locations, including the raised bed garden, a clay pot, rock gardens, and even on a sunny windowsill. The most important factor is direct sunlight and a well-draining soil. Otherwise, thyme requires little maintenance and care.

The best time to plant out your thyme seedlings is on or after the last frost date. While thyme is a cold hardy perennial plant, the young seedlings are more vulnerable to frost damage than established plants.

Thyme and rosemary seedlings
Young thyme plants growing indoors before transplanting.

So for new plants, the last spring frost date is a good time to transplant outdoors. By this time, the seedlings should be about 4-5 weeks old, and strong enough to establish roots in your garden soil.

Thyme plant basics:

  • Lighting – Thyme prefers full sun, though it will tolerate partial shade.
  • Spacing – Thyme plants should be spaced 8-12″ apart from one another. Creeping thyme will naturally spread, while common thyme (the type used as an herb) tends to stay compact and bushy.
  • Soil – Thyme does not like heavy clay soil, and is one of the few garden plants that prefers alkaline soil. Plants will handle dry soil and even poor soil conditions. The most important factor is good drainage, as thyme plants with wet feet will often succumb to root rot.
  • Fertilizer – Thyme is not a particularly heavy feeder, though it does do best in medium-fertility. Don’t bother over-feeding with nutrients unless your plants show signs of poor growth or deficiency.
  • Pruning and harvesting – Thyme plants are very resilient and can be harvested at virtually any time. Be sure to snip off the new, tender growth rather than the woody stems towards the lower part of the plant.
Thyme plant shoot
Thyme plant on border of herb garden raised bed.

Thyme is one of those lovely plants that doesn’t ask much of us gardeners. Once established, this perennial herb will provide bountiful, fragrant thyme for years to come.

Thyme Growing FAQs

If you are new to growing thyme, you may encounter some issues or concerns along the way. Here are the most common questions about growing thyme:

How can I use fresh thyme?

First off, how are you going to use thyme once you have your first harvest? There are so many possible use cases, but here are a few ideas:

  • Soups and stews. Thyme adds unbelievable, sweet and aromatic flavor to hearty fall soups and stews. Add a few sprigs to homemade the pot, or infuse into your tomato or hot sauce!
  • Dehydrate it for later use. One of the best preservation methods is to dry your thyme. You can use a purpose built food dehydrator, or simply hang-dry the thyme until it is brittle to the touch. For the best flavor, store the thyme whole, only crushing it just before use.
  • Marinades. Chicken, beef, and pork marinades can be leveled-up with just 1 or 2 sprigs of fresh thyme.
  • Herb butter. Herb butter is insanely delicious, but also super easy. If you want to wow your dinner guests, make a simple garlic and thyme butter for steak, mashed potatoes, or toast.

Since thyme comes back every year, don’t worry if you can’t use all of it every season. There’ll be more to come next spring!

What should I grow with thyme?

The best companion plants for thyme are other herbs, vegetables, and flowers. However, since thyme comes in so many forms, you may even find a use for it in your perennial landscape beds, along a rock wall, or in decorative pots.

​Here are a few good companion plants for thyme:

  • Basil
  • Cilantro
  • Cosmos
  • Lavendar
  • Marigolds
  • Mint (in pots, invasive)
  • Oregano (in pots, invasive)
  • Parsley
  • Peppers
  • Rosemary
  • Sedum (stonecrop)
  • Tarragon
  • Tomatoes
  • Zinnias
Thyme plant with multiple shoots
Thyme with parsley plant nearby.

Thyme is a great companion for virtually any plant, so get creative. It looks great along the edges of raised beds or flower gardens, though we like to keep it in our dedicated herb garden. Check out our herb garden raised bed plans here.

How big does a thyme plant grow?

Common thyme grows to about 12″ tall when mature. Thyme plants are known to get a bit scraggly and unkempt, but harvesting outer branches helps keep it tidy.

How often should I water thyme?

While thyme needs plenty of light, it doesn’t require nearly as much water as some other herbs or veggies. The small leaves mean less transpiration, and thus less water usage by the plants.

Water thyme only when the soil is dry 2-3″ below the surface. Thyme can handle drought very well, and over-watering can cause growth issues.

Should I remove flowers from thyme?

Thyme plants flower in mid-summer as a natural part of their life cycle. Mature plants will naturally flower each season.

Whether your remove the flowers is up to you. Leaving them to bloom is attractive and pollinator-friendly. However, flowering plants use more energy to produce seed instead of leaves for you to harvest.

So, if you want the most usable thyme, remove the flowers before they open. Snip just below the first flower buds on each stem to encourage more foliage.

Can I propagate thyme from cuttings?

Thyme can easily be propagated from cuttings. Cut a portion of the parent plant down to the woody base. Remove lower leaves and submerge the lower nodes of the cut end in moist potting soil and cover with a plastic bottle to keep the foliage humid.

Woody thyme stem
Woody thyme stems on lower part of the plant.

Alternatively, you can bury an existing stem in nearby soil without taking a cutting at all. The plant tissue will “recognize” that it is in soil and send out new roots. Then, the new plant can be dug up and transplanted to a new location.

Pests and diseases

Thyme may be attacked by a number of pests, most often aphids and spider mites. These can be sprayed off with a strong blast from the hose, and will often be eaten by beneficial insects like ladybug larvae.

The most common disease for thyme is alternaria blight, which causes yellow to black spots on the leaves. It usually starts on the lower leaves that are shaded and more damp than the upper foliage. Remove any affected leaves immediately, and space the plants wider for better air circulation.

I hope this article helps you start thyme from seed with success. Having your own homegrown thyme is a source of pride (and amazing flavor). Happy growing!

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