Seeds of the cornflower (Centaurea cyanus). Photograph by Esme Webb
How Love burns through the Putting in the Seed
On through the watching for that early birth
When, just as the soil tarnishes with weed,
The sturdy seedling with arched body comes
Shouldering its way and shedding the earth crumbs.
—Robert Frost, “Putting in the Seed”
For some, it’s planting fall bulbs and anticipating the explosion of spring color, for others it’s edging out a brand new perennial bed. For me, the most thrilling aspect of being a gardener is sowing a seed and watching it spring to life. It feels nothing short of miraculous every single time, and success depends on exactly the right conditions. This post is a small introduction to my first year as a gardener at the Cloisters, and my adventures in propagation so far.
I trained as a gardener at Wave Hill, a fantastic public garden just up the river from us. I learned a great many things there, but Wave Hill’s chief propagator, Susannah Strazzera, really fostered my interest in propagation. It was at Wave Hill that I first learned the ins and outs of “pricking out,” “potting up,” and “growing on,” as well as the function of mysteriously named tools like “dibbles” and “widgers.” (The former is used to make planting holes, the latter is used for transplanting delicate seedlings without disturbing their roots.) Growing plants from seed reminded me of cooking—another interest of mine—which may be why I found it so appealing. Part science and part art, propagation requires not only an understanding of what a seed needs to germinate successfully, but also a willingness to experiment and to follow your instincts. Most of all, you need to keep strict records so that you can duplicate your successes and not your mistakes!
Grow houses are handy for starting seeds and acclimatizing young plants to outdoor conditions. Photograph by Esme Webb
The Cloisters grows many rare or difficult-to-find species. It’s sometimes easier for us to find seed of the plants we need than to find the plants themselves, so it is extremely important to have a good propagation program. While many of the seeds we use will germinate quickly and easily in potting mix or garden soil under a fairly wide range of conditions (sesame, wallflower, and green orach all germinated readily for me this spring), some plants have very specific temperature and light requirements. Still other plants require complicated rotations between cold and warm temperatures, a process known as stratification, and can take many months or even years to germinate. These kinds of plants are especially difficult for us to grow. Lady’s mantle, acanthus, and deadly nightshade all fit in this category, as they may require careful monitoring and greenhouse environments to germinate.
A wallflower (Cheiranthus cheiri syn. Erysimum cheiri) grown from seed blooms in Bonnefont garden. Photograph by Esme Webb
This year, with only modest equipment and space, I was able to grow an exciting list of species. The following plants were propagated with only seed trays or flats, capillary mats, germination mix, and simple grow lights: purple foxglove, violas, mullein, calendula, gum arabic, Jacob’s ladder, sesame, columbine, lupine, dianthus, English daisy, creeping thyme, green orach, stavesacre, wallflower, cornflower, Dutch field peas, collard greens, arugula, bottle gourd, sea holly, viper’s bugloss, dame’s rocket, and downy thornapple. (Some of these plants were lucky enough to have been featured on the blog.)
The sesame (Sesamum indicum) was a particularly fun plant to grow, because it had been many years since we’d seen it here at the Cloisters and I wasn’t at all sure what to expect. (For a wonderful history of sesame, see “Open, Sesame,” August 3, 2012). I sowed the sesame seeds indoors in early May at about 70 degrees and they germinated within five days. About two weeks later, I pricked them out (”pricking out” means to separate and pot up individual seedlings in their own containers) and, two weeks after that, planted them in Bonnefont garden. They started to produce flowers in July, and continued to flower well into September.
Stavesacre (Delphinium staphisagria), growing on in a plastic propagation pot. Photograph by Esme Webb
Another exciting one to try was the stavesacre (Delphinium staphisagria). This beautiful, Mediterranean plant is generally grown as an annual in our part of the world. We had a specimen growing in our cold frames, from which I collected seed in August, eager to see if I could grow it on through the winter. I experimented with about a dozen seeds in a flat and waited for signs of germination. For five weeks nothing happened and I was ready to give up on them completely when—finally—germination! I potted up several healthy specimens that we may try to overwinter in cold frames, but if they don’t make it we’ll be prepared to start them from seed again in the spring.
Gum arabic (Acacia senegal) propagated from seed and growing in Bonnefont garden. Photograph by Esme Webb
All seeds require some form of scarification, or alteration to their seed coat, before they will germinate. With many seeds this is achieved simply by immersion in damp soil. For others, the freeze and thaw of winter and spring is what is needed to break down the seed’s coat. Other seeds, such as those of the plant gum arabic (Acacia senegal) require even more dramatic scarification. I immersed the large seeds of the gum arabic in boiling water for about a minute before transferring them to a cold bath for twenty-four hours and then sowing them in a flat. A short three days later, the gum arabic had germinated very well. Seed packets generally come with specific instructions on scarification and sowing—if not, refer to a trusted seed-starting book for instructions.
My propagation efforts this year have been relatively modest and experimental, but next year I hope to tackle a broader variety of plants. I hope to continue posting about my successes—and failures—with more detailed explanations of our methods and equipment. You’ll hear from me in the spring, when the real fun begins!
Tags: arugula, bottle gourd, calendula, collard greens, Columbine, cornflower, creeping thyme, dame's rocket, dianthus, downy thornapple, Dutch field peas, English daisy, green orach, gum arabic, Jacob's ladder, lupine, mullein, purple foxglove, sea holly, sesame, Sesamum indicum, stavesacre, violas, viper's bugloss, wallflower