Tips to Germinate Herbs Indoors


We have talked about why to try to germinate seeds during the off season in my last blog post. Now in this post I would like to share a few things herbs need to sprout and a few tips for germinating seeds yourself.

As I have said, I have not had very good success in the past starting my herbs as seeds. The plants are so tiny and leggy when they sprout; they just don’t seem like they will be sturdy enough to thrive. The challenge of trying to remember to keep them watered without making a big mess only complicates the project. This attempt to germinate herb seeds has been much more successful and has set me up to be more confident when I start seeds in the future.

My Seed Starting Setup:

To sprout my seeds I set up a phase 1 with a heat mat and a phase 2 with a light.

  • First I filled a disposable aluminum casserole tray with some of the compost that we use to fill our outdoor raised garden beds.
  • I then attached rows of green floral wire across the tray about 2.5 inches apart and labeled each row by taping a sticky note on with packing tape. I wanted to be able to plant a different herb in each row to maximize my use of space.
  • After I followed the direction on each packet regarding how deep to plant the seeds, I watered them well.
  • I put the entire tray on top of the heating mat, which I plugged in on top of my dryer. I have been waiting for them to begin to germinate, and my somewhat limited patience is starting to pay off! My calendula, catnip, valerian, and Echinacea are starting to sprout.
  • Now that the majority of the seeds have begun to sprout I have moved them off the dryer and onto a wood shelf in my bedroom (to try to limit how much my toddler can get into it.)
  • I hung a fluorescent tube light from the shelf above so it is only a few inches above my little sprouts. This should give them plenty of light and prevent them from getting too leggy.

What soil to use?

Many tips I read strongly suggested using a specific seed starting mix (lighter than potting soil) because it is easier for tiny herb seeds to push through but I found that I have very good luck with the horse manure/compost mix right out of our garden. (We’ve also used alpaca manure & that is a LOT denser & may not work as well. So think lightweight.)

If you want to start seeds in the same pots that the plant will grow in I have seen suggestions to fill the pot with soil then add 2 inches of seed starting mix or lighter soil to the top to plant the seeds in. This way they can benefit from having good potting soil for the roots as the plant grows and have mix that is easy for the plant to push through.

What herbs need to germinate:

Time. Many herbs are very slow to germinate, taking 10 days up to 4 weeks to show themselves. Be patient and assume the best. On average perennial herbs like thyme, sage, mint, lemon balm, mint, etc. take longer to sprout than annuals, about 21 days give or take.

Plenty of space. Some herbs such as borage, cilantro, dill, and fennel do not respond well to being transplanted and should be sown directly in the ground outside or in pots large enough to keep them in.

Specific Temperatures. In general, herbs like moderate 60-70 degree temperatures to germinate well. For most herbs the germination rate goes up and the length of time it takes for a seed to sprout goes down as the temperature increases.

Cool season herbs like calendula and cilantro (Both herbs I want to grow successfully) need cooler moister temperatures to sprout. They can be planted outside in early spring and survive light spring frosts. I planted my calendula in my tray on the heating pad and it was actually the first plant to sprout.

Moisture. Most herbs seem to like to stay moist but not soggy. Do not let your soil dry out while you are waiting for the seeds to sprout, but don’t keep it too soggy or mold will start to grow. I’ll be posting a short blog post soon on the waterer I made that is perfect for giving your seeds just the right amount of water easily.

Consideration about Lighting. You can germinate herbs in indirect light if sprouting in soil, or even in the dark if sprouting in paper towels. I sprouted my seeds on top of my dryer in my laundry room which receives indirect light from two west-facing windows. Some people suggest pre-germinating your seeds by letting them sit folded into moist paper towel until they sprout. Here is a link to an article on sprouting seeds in paper towels.

Move your tray of herb sprouts off from the heat mat and place it under the grow light once they sprout. I am using a plain fluorescent tube light suspended from a shelf for mine. Many people suggest keeping your lights 2-4 inches above the plants; this encourages sturdy, stocky sprouts. This is actually working well for me this time; My sprouts are looking strong & healthy so far!

I hope this has given you some fresh information about caring for indoor herbs and starting seeds to eventually plant outside. Here are a few related posts that you might find helpful as well!




One thought on “Tips to Germinate Herbs Indoors

  1. I had never thought to use a heating mat to germinate seeds, I will now. Thank you. I use a mixture of compost and vermicast for getting my seeds up and running and the heat mat will be a great addition.


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