Propagation

The following are ways to increase your supply, other than by seed, once you have established plants, whether they originated in your yard from seed or as plants purchased from the nursery:

Division—You will want to divide a plant if it has become invasive or needs rejuvenating. If the center of the plant dies out, leaving foliage circling a "bald spot", it's time to divide to keep the plant healthy and productive. The following can be divided: catnip, Roman chamomile, chives, germander, lavender, lemon balm, mints, oregano, garden sage, French tarragon, and thyme. In the course of dividing plants, you must transplant them. The bonus by-products of division are the resulting "new" plants divided off the old clumps, which you can then transplant to another part of the garden.

Early spring before the plants start to re-grow, is the best time to divide. This is because the foliage will not be spoiled by chopping, moving, and moisture loss, and the plants will have time to reestablish themselves during the growing season.

The best tools for dividing are a sharp spade and garden fork, although a round- or flat-headed shovel will do; the sharper the better in order to make clean cuts to the roots. Start with a large-tined garden fork and wiggle it down into the clump of foliage at the point you wish to divide. Sometimes, especially if the soil is loose and malleable, you can pull apart and separate a clump away from the main clump with just the fork. It is also helpful to use two forks, back-to-back, to tease apart the divisions. Fleshy roots (horseradish and lovage) should be forked out, then sliced apart with a sharp knife before replanting. Bulbous roots of chives can be pulled apart or separated with a trowel.

For woody-centered herbs, such as rosemary, you will need to make a clean cut with a spade or shovel straight down through the foliage and roots to completely divide the plant. If the center has died out, cut shovel-width divisions of vigorous growth from around the edges, and lift them out of the ground. Dig up and compost the woody center. Subdivide your clumps if you really want a lot of plants. Replant and water the divisions as soon as possible.

Layering—This is a very easy way to propagate. At the beginning of the growing season, choose a branch near the base of the mother plant that is flexible enough to be bent to the ground. Strip the foliage from the part that will touch the ground, about one third of the branch from the top down. Bend a wire into a U shape and pin the branch to the ground. Keep the soil moist until roots are set. At the end of the season, cut the branch away from the mother plant and plant it in its new location.

Cuttings—Make cuttings to get a lot more plants in the spring or take cuttings in the fall to have plants over the winter. Choose healthy growth that is mature but not woody (it still bends but is not too succulent) and not in bloom. Cut stems 3 to 4" from the tips with a razor blade or sharp knife. Strip the leaves and small branches to half of each stem, and insert immediately into a moist, very light medium, such as a ready-made soil-less growing mix. Some cuttings, such as scented geraniums, root best if allowed to callus over for 8 hours in a cool place. Do not allow leaves to touch or overlap. Water gently to firm the soil around the stems, and cover with a clear plastic bag. Set in bright light but not direct sunlight. Mist the plants daily to maintain high humidity. Remove any dead matter immediately. You can tell the plant has rooted when it resists a light tug and when new growth appears. From cutting to rooting should take between 2 and 3 weeks. At this point, remove the covering and water normally for a few days before transplanting.

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