Silene stenophylla, regenerated from a 32,000-year-old seed.
(Photograph: National Academy of Sciences)
The dry little speck that develops into a magnificent plant is one of those miracles that happens so often that it’s easy to take it for granted. But, if we stop and consider the way plants guarantee that a new generation will carry on their genes, we have to marvel at the elegance of nature’s design. Protected by a tough coat, seed can tolerate conditions much harsher than its living parent could ever survive, and it can wait years for the proper conditions to germinate. In the case of Silene stenophylla, proper conditions were scientists removing its seed from a 32,000 year-old squirrel burrow in the Siberian permafrost and growing it. This “delicate” arctic campion grew, bloomed and set seed after millennia of patient dormancy. Other reports of Jerusalem date palm and lotus seed remaining viable for a mere thousand years is testament to the phenomenal adaptation and resilience of plants. (At the other end of the spectrum, some tropical seed remains viable only briefly, and must be sown fresh for good results.) In order to make management of a crop easier, agricultural seed has been selected to germinate all at the same time, a characteristic that would be disastrous for wild species. Ordinary garden seed, collected the previous year and packed and stored in dry conditions, is a valuable resource for gardeners.
Growing plants from seed allows the gardener a much broader range of plant choices than you’ll find at your local garden centers. With all the offerings online, in seed catalogs or on the racks in the big-box stores, the choices can be overwhelming. When selecting varieties, consider not only appearance, but yield, disease resistance and flavor. Gardeners’ reviews in internet forums can be useful in making a decision.
As the time for starting seeds for the vegetable garden approaches, a few pointers may be helpful:
- Start tomatoes on St. Patrick’s Day, or thereabouts (Eight weeks is standard lead time before planting in the garden, but if mid-May is still too chilly, plants can always be held a couple more weeks.) The majority of garden vegetables can be started from seed at this time. Cabbage can wait a few weeks, and for the vines, (cucumber, melon, squash, etc.) delay indoor planting until the last week of April, because setting out these heat-loving plants too early will only retard their growth.
- Root crops should be sown directly in the garden.
- Growing annual and perennial flowers from seed is an economical way to grow large numbers of plants and also to try unusual varieties. Be aware that some perennials require stratification (periods of cold that break dormancy) before they will germinate.
- Seed saved by friends and neighbors in your area are often a good bet. They’ve been tested by others who have about the same conditions as yours.
- Start small seeds in flats and larger seeds in cell packs, using commercial potting soil. (The garden books advise sterilizing the cell packs if they’ve been used before, and also using sterilized growing medium; I do neither and have never had a problem.) Garden soil can contain weed seeds and pathogens; potting mix is the safer choice.
- Don’t trust your memory; identify flats with popsicle sticks labeled with indelible marker.
- Germinate seeds in a warm room. Bottom heat aids germination; a table over a baseboard or radiator is excellent, as long as it’s not too hot.
- Cover germinating seeds with a sheet of plastic to retain moisture. (Dry cleaner’s bags work well, held in place with something light – I use chopsticks.) Monitor closely to be sure soil is damp, not wet. Remove plastic as soon as seeds break the surface. Allow one week beyond the germination times stated on the seed packet. If germination is disappointing or absent, resort to Plan B.
- The humidity that is conducive to seed germination is also the perfect environment for the growth of fungi and bacteria that can attack seeds or seedlings in a condition called damping off. Keep soil moist, but not wet; excessive moisture is the primary culprit of this disease. A small fan running on slow speed (placed well away from the seedlings) or a slightly open window on warm days will help by circulating air and keeping surfaces dry.
- Move sprouted seeds immediately to the brightest light available. A sunny window is good; or artificial lights (fluorescent or LED) hung on a chain can be positioned a few inches from the growing plants and moved as necessary.
- After sprouted seeds have their first set of true leaves, they may require thinning. Plants that are too crowded will compete with each other and none will flourish, so don’t skip this step. Cutting off unwanted plants with small scissors is preferable to pulling because it won’t disturb delicate roots.
- When plants outgrow their cells or small pots, move up to a 2.5-3” pot, using a plant stake or plastic spoon to separate and lift the seedlings. Water thoroughly with a dilute water-soluble fertilizer.
- Vine crops (cucumbers, melons, squash, etc.) are best started in peat pots because they can be transplanted without disturbing their temperamental roots. Peat pots are mushy when wet, so at planting time, soak them well, tear them gently open and plant directly into the ground. Trim off any pot that will protrude above the soil; this will cause wicking action that can rapidly rob moisture from the plant.
- Harden off plants before planting out in the garden, gradually exposing plants, over the course of a couple of weeks, to increasing sunlight and cool weather.
For those who haven’t tried it, growing your own plants from seed is a gratifying experience – there’s no better way to tune in to a plant’s requirements and hone your horticultural instincts, and it’s an economical way to try new varieties and keep your garden interesting.