Part 2 of 2 - By Jill Henderson
In the first part of this two-part series we covered propagating herbs through the process of division. In this article, we’ll finish the art of propagation through layering and stem cuttings – all fast and easy ways of increasing your perennial herbs and flowers.
Layering is a method of propagation that involves rooting actively growing stems while they are still attached to the parent plant. This system is ideal for plants that have not reached a mature size appropriate for division. Layering is most successful when applied in the spring or early summer while herbs such as sage, savory, hyssop, rosemary and tarragon are adding fresh new growth.
Select long, flexible stems and bend them gently to the ground, taking care not to break them where they meet the parent plant. Strip off all but the topmost leaves and push the stem end several inches (8 to 13 cm) into the soil. Use a rock or other device to pin the stem firmly to the ground and cover lightly with mulch. Be sure to leave the leafy portion of the stem protruding 2 to 3 in. (5 to 8 cm) above the soil. If necessary, prop it upright with a small stone or stick until it begins to grow on its own.
During the course of the growing season, the stem will root and eventually it will be able to survive on its own without nourishment from the parent plant. Occasionally a fast growing herb will put down enough roots by late summer to survive transplanting. However, to ensure a vigorous new start that can survive winter on its own, do not cut the stem that connects the two plants or attempt to transplant the new start until the spring of the following year.
Herbs such as mint, thyme, oregano, and marjoram can also be propagated using layering. These herbs tend to sprawl or creep, and most of them will naturally root where they touch the soil. Simply covering the existing stems with 1 or 2 in. (5 to 8 cm) of soil can speed up this natural process.
While layering and root division are two excellent ways to propagate herbs, rooting stem cuttings has its advantages. Rooting stem cuttings is faster than layering and more productive than divisions. Both woody and herbaceous herbs respond well to this procedure.
To propagate new plants from stem cuttings, select young, healthy, actively growing stems that are at least 6 in. (15 cm) long and cut them from the parent plant with a very sharp pair of scissors. The cut should be as clean as possible without any ragged ends. Strip off all of the leaves from the lower two-thirds of the stem and dip the cut end in rooting powder. Plant the cutting at least 3 in. (8 cm) deep in a large flat or pot filled with moist, soilless potting mix. Space the cuttings 4 to 6 in. (10 to 15 cm) apart. Place the flat in a lightly shaded area and keep the soil in the flat moist but not soggy until the stems begin to root.
A good way to maintain the relatively humid conditions that stem cuttings need while growing new roots is to use a one a clear, lidded clothes storage tub that is at least 12 in. (30 cm) deep. Fill the bottom with 6 to 8 in. (15 to 20 cm) of potting soil and moisten with a spray bottle. Dip the cut stem ends in rooting powder and push them into the soil at least 3 in. (8 cm) deep. Loosely cover the top with the lid, venting as needed by turning it at an angle to the tub’s rim.
Root formation can take up to six weeks. Once the small herbs begin to grow new leaves, allow the soil to dry slightly between watering and move the flat into a sunnier area for two or more weeks before transplanting to the garden.
A few herbs such as lemon balm, sage, catnip, and mint will also root well in water. Select, cut, and strip stems as you would for the method used above and place the cut end in 3 to 4 in. (8 to 10 cm) of water. A clear jar or glass is a good way to monitor the root formation of the new cuttings. Place the jar in a sunny but not hot window indoors. When the stems have several long roots, transplant them to a pot and allow them to grow until their root systems are robust enough to survive out in the garden.
By using these propagation methods you can quickly and easily increase your herb plantings.
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