Divided They Stand: Sharing Herbs by Dividing THem


| April/May 1993



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One of the greatest joys of herb gardening for me is sharing my perennial plants with other gardeners. (I love to receive plants, too.) But buying plants to give away can be expensive, and raising plants from ­cuttings or seeds takes time. Thus, I take comfort in knowing that I can satisfy my urge to share my herbs without spending a cent and at the cost of only a few minutes of my time and a little elbow grease. I do this by dividing them.

Vegetative (asexual) methods are the only way to propagate certain herbs, such as French tarragon, which doesn’t set seed, or those cultivars of lavenders, oreganos, and thymes that don’t come true from seed. These methods ensure that offspring are ­genetically identical to their parents, that (barring a rare mutation) any start of tarragon that I give you will be identical to the mother plant and to its mother plant, and so on back through dozens of generations.

Division is only one method of vegetative propagation; others include taking stem, root, or leaf cuttings (see “Growing Herbs from Stem Cuttings”, The Herb Companion, February/March 1993), tissue culture, and layering (see “Layering: Propagation without Separation”, August/September 1990). ­Division is my favorite method because it’s quick: it takes just minutes versus the weeks or months required to obtain plants from cuttings. Division requires no fancy equipment—no lights, heating cables, cold frames, or propagating chambers. The new plants (called divisions) are much bigger than rooted cuttings, and they come equipped with all the parts (roots, stems, leaves) they need to start growing in their new location.

Although my motive for dividing perennial herbs is to obtain more plants to give away or to fill my own beds, there is another good reason to divide them. When I first set them in the ground, I give my plants plenty of room; small ones often look puny and lonesome in a sea of bare soil. With sun, water, and warmth, though, they soon expand outward, quickly using up their allotted space. The more rampant spreaders, such as yarrow, begin trespassing on the territory of their neighbors. Eventually, the enlarged plants must pay a price. Typically, the younger roots at the edge of the plant get their nutrients from the soil in the new space, but the older central roots have exhausted the soil they’re in; they weaken and die, as does the original top. What’s left is a ring of healthy plant material around a dead center; what’s needed is to move the good parts to fresh soil and to dig out and discard the old, worn-out inside part.

How Often to Divide Herbs

Every book I’ve read recommends dividing most perennial herbs about every three years, but I do it more often, even annually if the plants are growing well. If I put it off, the plants get woodier and much harder to dig. Another benefit is a more frequent change of exhausted soil for fresh, which makes sense to me.

When to Divide Herbs

Here in Massachusetts, I start thinking about dividing my herbs in April, though late snowstorms can postpone the actual digging for days or weeks. I remove the winter mulch of pine ­needles gradually, in two or three steps, so as not to expose the plants to the harsh realities of the weather too abruptly. As the tops begin to make a little growth, I see that the bee balm is beginning to tangle with the lemon balm, the lady’s-mantle is mingling with the orris, and the fern-leaved tansy is moving out of its enclosure of small stones. As the clump of chives ­begins to send up dark green succulent fingers, I envision it cut into four or six sections, each a mass of lavender flowers come June.





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