Let’s Plant Some Herbs – Propagation

Seeding is our favorite form of propagation. A seed is a repository for all the genetic diversity of the ancient wildness of these potent medicinals. When you are looking for medicine in a herb, you want to use the purest, strongest strain of the species you can get; in other words, you want the original, unchanged, wildest form available. So you will not, in most cases, choose a hybrid, which is indicated by a multiplication sign between a plant’s genus and species name or by a proper name within single quotes, like ‘Jenny’. And you won’t choose varieties developed for a wide array of flower colors or disease resistance. Seeds of unselected, wilder species will give you the full range of biodiversity possible for the herb – which makes it perfect for use as herbal medicine.

Most of the herbs featured in this website can be easily sown from seed. You will find instructions for the propagation methods {stem cuttings, root cuttings, root division, and layering} within this article. Our favorite seed sources are listed in the page ‘Buying and Ordering Plants’. We recommend that you seek out certified organic sources or get to know the seed company’s practices personally. We support small, local seed exchanges and regional seed houses whose activities are transparent, and we avoid those that trade in genetically modified or engineered seeds or plants.

Starting Seeds:

There are a few herbs that germinate best when they are seeded directly in the garden. However, most get a better start when sown indoors or in a greenhouse. You can start seeds in purchased seed trays or flats, recycled plastic nursery pots, or just about anything you have available that’s an appropriate size and shape: egg cartons, half clamshells, or paper cups, for example. If you can, start seeds in containers with individual cells. That way, when it’s time to transplant, you won’t have to disturb the seedlings’ roots as much as you would while separating seedlings started in a large container.

Seed-Starting Mix Recipes:

You can purchase an organic seed-starting mix at most hardware or garden stores, or you can make your own. Here are a few sample recipes.

Seed-Starting Mix 1

1 part organic potting soil

1 part perlite or vermiculite

Seed-Starting Mix 2

1 part garden soil

1 part well-sifted organic compost

2 parts horticultural sand or a combination of sand, perlite, vermiculite, and coir

Seed-Starting Mix 3

1 part well-sifted organic compost

1 part perlite or vermiculite

1 part coir

How to Plant Seeds:

Follow these instructions for sowing and nurturing your newly planted seeds.

  1. Make sure your mixture is moist but not soggy. Fill your clean, disinfected containers with the mix, and lightly tamp it down to settle and firm it.
  2. Make a shallow indentation with your finger or a pencil or chopstick and drop several seeds. Unless you’re planning a huge garden, do not sow all of the seeds in a packet; save some for a second sowing or the next season. In most cases, the average individual or family will only need 5 to 20 plants of a particular herb.
  3. Cover the seeds lightly with the seed-starting mix to a depth of two to three times the diameter of the seed. Very small seeds will get just the barest cover or will be pressed into the soil surface.
  4. Water or mist the flat or container gently, label it with the name of the herb and the date and place it in a warm location. If you are starting seeds early in the spring and the seeds need warm soil to germinate, you may want to purchase heating cables or pads {available online} or place the containers near a radiator or heater. A bright east- or west- facing windowsill with indirect light can suffice for germination. Most seeds germinate best between 60 and 80 degrees F.
  5. Label each herb container or tray with the herb name and the date. Keep the seedlings gently watered or misted so they remain moist but not soggy. {And if you will be gone for the better part of each day, cover the containers or trays with sheets of plastic wrap or plastic bags to keep in warmth and moisture. Once the seeds have germinated, remove the covering.} Make sure new emerging seedlings get 6 hours of sunlight daily. If they do not, you will need to supplement with fluorescent, LED, or grow lights. Germination times vary from several days to several weeks.
  6. The first leaves that emerge with germination {called the cotyledons} will be followed by the “true leaves,” which will look more like the mature leaves of the herb. You can transplant a plant to its own container or an outdoor bed after the true leaves have appeared, but it’s best to wait until there are several sets of true leaves and the plant looks healthy and strong.

Transplanting Outdoors:

If you are starting seeds indoors, sow them 4 to 6 weeks before the last spring frost date in your area. Once the frost date has passed, you can safely transplant seedlings into outdoor pots or beds.

As you notice that the young plants are ready, take them outdoors in their seed-starting trays or containers for a few days, and bring them back inside before nightfall. This process is called “hardening off,” and it helps the plants become used to the temperatures and conditions outside. After several days of hardening off, leave the plants outside overnight. Then transplant them into beds or containers, preferably in the late afternoon or on a cool day. If they are going into the ground, dig a hole bigger than the seedling and place a handful of compost or aged manure at the bottom. Place the seedling into the depression and firm the soil around it, burying the main stem slightly deeper than it had been growing in the seed-starting medium. Water it gently.

Stem Cutting:

If you have access to a mature plant of the species you would like to grow, in many cases, you can propagate by stem cuttings. Cuttings will result in a new plant in a matter of weeks, and you’ll have a success rate of 50 to 90 percent, depending on the herb. Cuttings are best taken in spring or early summer.

Here is how to propagate from stem cuttings.

  1. Make a mixture of 1 part sand and 1 part perlite, or 1 part sand and 1 part moistened coir, with an optional smattering of compost tossed into the mix, and moisten it until it is wet but not soggy. This will be your rooting medium.
  2. Fill clean, sterilized pots with the mixture, leaving an inch or so at the rim of the pot. Use your little finger, a pencil, or a chopstick to poke a 2-inch-deep hole in the mix for each cutting you will be starting.
  3. Snip a 4- to 6- inch section of a healthy stem, and remove all leaves from the bottom one-third to one-half of the cutting, leaving the only naked stem on that portion. You may also pinch off the tiny tip of the cutting.
  4. As an option, you can dip the lower half of the stem cutting into rooting hormone or a strong tea made from willow bark or twigs. Insert the cutting into the hole you have poked in the rooting medium. Make sure the area you stripped of leaves is below the soil.
  5. Check the moisture level of the rooting medium once or twice daily. You can also place a plastic bag over the stem cutting, making sure it doesn’t touch the leaves. {Insert a bent coat hanger, chopstick, or another support around and above the cutting.} Then cut slits in the bag to allow fresh air to reach the plant.
  6. Place the cutting in the bright but indirect light. If the air temperature is going to fall below 65 degrees F, consider adding bottom heat {in the form of heating coils or pads} for greater success.
  7. Stem cuttings will form roots in 2 to 4 weeks. After 2 weeks, check to see if the cutting has rooted by gently tugging on its top leaves to see if there is resistance, which is a sign that roots have formed.
  8. As soon as possible after you verify that the cutting has rooted, transplant the seedling into a pot or its permanent location in the ground.

In the fall, you can take hardwood cuttings from woody plants during their dormant period. Mid-autumn id often the best time to collect and plant cuttings, because the plants will have time to form roots before buds begin to grow.

  1. Make a mixture of 1 part sand and 1 part perlite, or 1 part sand and 1 part moistened coir, with an optional smattering of compost tossed into the mix, and moisten it until it is wet but not soggy. This will be your rooting medium.
  2. Fill clean, sterilized pots with the mixture, leaving an inch or so at the rim of the pot.
  3. Collect 4- to 8- inch cuttings from vigorous, 1-year-old wood, a few inches below the tip of the branch or stem. Make a sloping cut at each tip, slightly above a bud, and a straight cut at each base, slightly below the bud.
  4. Place the cuttings 2 to 4 inches apart in the medium, with the top bud of each about 1 inch above the rooting medium’s surface. Be sure the cuttings point upward, and double-check that you have stuck the ends with straight cuts into the medium.
  5. Place the cuttings {along with their rooting medium mixture} in a “nursery” trench that you have dug in the ground soon after you harvest them from the mother plant. This trench will allow them to overwinter before they are planted individually in the ground. Cover the cuttings with 6 to 8 inches of mulch.
  6. Keep the cuttings moist over the winter. Remove the mulch and move your rooted cuttings to their new homes in the spring.

Root Cuttings:

Plants that have taproots {like carrots} are best divided by actually taking slices from the root of the mature plant. This method also works well for plants that have long, creeping roots, rhizomes {underground stems with a root-like appearance} or runners.

  1. Dig the root carefully and gently brush off any excess soil.
  2. If the plant has a taproot, cut off 1-inch slices. If you have a thin creeping rhizome, notice the growing nodes {bumps or lines on the root} and divide the rhizome into sections that each has at least two of these nodes.
  3. Using the same potting mix that you would for stem cuttings, fill a pot one-half to two-thirds full. Lay the taproot or thin root sections on the surface and cover it with more potting mix, to just below the rim of the pot. Do not compress the soil.
  4. Label your new starts and water them well.
  5. When you notice a new plant emerging from the soil surface, you can transplant it into its permanent home.

Root Division:

Sometimes the best way to gain a new plant is to take advantage of someone else’s excess! There are quite a few plants that expand and spread by runners {underground stems} and others that self-seed profusely and form massive plantings. These can be lifted out of the soil and divided, and the resulting sections can be replanted. The same process can renew an older plant that has died out in the center. It’s done with perennial herbs that have fibrous roots {as distinguished from taproots} anytime during the growing season, but is perhaps best done in the fall, when the plants are beginning to die back, or in the early spring, when growth is starting to explode. Of course, check the individual herb to make sure that the herb you are working with is suited to this technique.

  1. Carefully dig and lift up the whole plant, making sure to get as much of the rootball as you possibly can. If the plant is large or unwieldy, you may want to prune it to a manageable size first.
  2. Shake off any excess soil and gently tease the root mass apart, sensing where it most easily wants to separate.
  3. If the root is large, hard to separate, or very dense, you can use a weeding tool, a digging fork, or even clippers or scissors to separate the roots.
  4. Replant all sections immediately, either into pots or in the garden. If the herb likes a richer soil, fill the new holes with compost to give the divisions some nutrition for the journey to maturity.
  5. If you haven’t already, prune the above-ground portions by at least half so that the newly disturbed roots won’t have to feed as much plant matter.
  6. Water thoroughly.

You can also use the same technique to separate offsets and side shoots from parent plants. Remove younger, smaller shoots from the outer edges of a rootball by breaking or cutting them off, making sure that each piece you remove has its own root system. Replant the offshoots immediately to the same depth as the original plant, and water it thoroughly.

Layering:

This is the oldest method of propagation, and it’s one that happens naturally as certain herbs age. The long, leggy stems of some plants droop down and rest on the soil, and when they touch at a node {a raised area on the stem where the leaf attaches}, roots will form. You can mimic this process by layering selected plants to create offspring.

  1. Choose a strong, healthy stem, and notice where it will easily dip to the earth. Remove all the side shoots and leaves from a 6- to 12- inch section at the point of soil contact.
  2. If you wish, you may use a knife to gently scrape the underside and outer woody portion of the stem for 1 to 2 inches at the point of soil contact.
  3. Fluff or rough up the soil where you plan to bring the stem into contact with it, mixing in a thin layer of compost or watering with liquid fertilizer.
  4. Press the stem to the earth. Anchor the stem with a stake, a U-shaped piece of wire, a stone, or something similar. Mound a layer of soil over the anchored section of the stem.
  5. Keep the area moist. Layering is a long process, but if you start in the spring, you should be able to separate your new plant in the fall.
  6. When roots form, snip off the portion that connects the new plant to the mother plant. Pot up the new plant immediately. If it’s going into the ground, transplant it in the fall, or keep it in a sheltered spot and wait until the following spring.

You can use this same technique to layer potted plants, too. Pull a runner or a long stem from the mother plant, and set it on top of the soil of a new pot. Make sure it is secure, as directed above. When it roots, you have a new potted herb already nestled in.