Water Works

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AS A COMMERCIAL HERB grower, I’ve growled more than once that home gardeners can’t expect to successfully propagate herbs from cuttings without spending a lot of money for equipment, but I repent. I’ve found a simple, inexpensive, effective way to root cuttings of many herb varieties; it’s probably the same method that your grandmother used. All you need is a glass of water and a windowsill.

I spent a recent summer experimenting with rooting cuttings of more than a dozen herb species in water, and I can tell you that this method, in some instances, will root cuttings as fast for you as my expensive automated propagation gadgets can for me. This method almost totally eliminates plant stress, which other­wise slows rooting, and it avoids some of the wilts and rots that plague home gardeners when they try to root cuttings in a soilless medium. (“Growing Herbs from Stem Cuttings” in the February/March 1993 Herb Companion addresses some of the difficulties.)

In comparing new and old gardening techniques, I find that traditional methods sometimes are at least as good as modern ones, but Grandma may not have told you all you need to know to make her way of rooting cuttings work as well for you as it did for her.

What works

Plant Propagation: Principles and Prac­tices, by Hudson T. Hartmann and Dale E. Kester, a text used by many professional propagators, states that water can be used to root cuttings of easily propagated species. I’ve found that many herbs fit that category.

Most of the herbs I tried rooted within two weeks or less: mints (Mentha ¥ piperita ‘Mitcham’ and M. spicata) in seven days, basil (five varieties of Ocimum basilicum) in five to ten days, patchouli (Pogostemon cablin) in ten, pineapple sage (Salvia elegans) in eleven, and lemon verbena (Aloysia triphylla) and a cultivar of rosemary (Rosmarinus officinalis ‘Arp’) in fourteen days. (Although basil is usually grown from seed, some new cultivars, such as Aussie Sweetie, Mulberry Dance, and Holly’s Painted, to name a few, either don’t flower well or don’t come true from seed, so rooting their cuttings is the most reliable way to propagate them.)

Some herbs were less successful. Scented geraniums took twenty-six days to root vigorously; an oregano (Origanum ¥ majoricum) took about as long, but the roots were weak and sparse. Fruit sage (S. dorisiana) took nearly four weeks. The two lavenders I tried, Lavandula angustifolia ‘Tucker’s Early Purple’ and L. a. ‘Sharon Ro­b­erts’, rooted in a little over six weeks, but only a small percentage of the Tucker’s Early Purple struck roots, and weak ones at that.

A few of the herbs didn’t respond at all. French tarragon (Artemisia dracunculus var. sativa), thyme (Thymus vulgaris ‘Provencal’), balm of Gilead ­(Cedronella canariensis), and myrtle (Myrtus communis) either rotted or had failed to root after two months. Two cultivars of common sage, S. officinalis ‘Rubriflora’ and S. o. ‘Albiflora’, did not root at all. (All of these can be propagated by division or are fairly easily rooted in a peat-based medium that is misted frequently.) I found that not all varieties of the same herb species rooted with the same speed or vigor, but this is also true with other propagation methods.