Thorough deadheading of flowers before they set seed may prolong the bloom time for some plants (as well as prevent unwanted self-sowing), but it will deprive you of an even more gratifying and optimistic task: obsessive seed collection. I fill my pockets at the end of the season if only to reassure myself that spring will come again. I find it hard to quit even when my pockets overflow. But I’m always glad to have plenty of extra seeds for winter seed swaps with friends.
How will you know when a seed is ripe for saving? Every plant has its own timing, and seeds are at least as varied as dog breeds, but rattling and release are two obvious clues. Look for ripening seed capsules, which usually change color, crisping up just before opening to reveal or eject the goods inside. Opium poppies (Papaver somniferum), for instance, go brown from stalk to seedhead, begin to rattle, and then open vents just under their rickrack cap. Tip bunches of poppy pods upside down into paper bags to collect the countless seeds. Milkweed (Asclepias) pods echo fall colors and begin to split just as the seeds inside ripen. Collect the russet-brown disks when they can be easily popped into a packet before their parachutes open and the wind catches them.
Sharing seeds—the careful handoff.
Butterfly weed (Asclepias tuberosa) seedpods beginning to open.
Rather than labeling the outside of your seed tins, write the name and date on a slip of paper and throw it in with the seeds.
Always collect seeds on a dry day and remember to label them with name and date. Coin envelopes are the traditional seed collection containers. You can purchase boxes of five hundred (that’s plenty for a season or two) and a good ten or twenty fit comfortably in a back pocket. They keep seeds dry, unless dropped in the birdbath, and are easy to write on. Small tins, spice jars, glassine stamp packets, and paper bags also work well. Resealable plastic bags are fine too as long as moisture isn’t trapped in the seed.
Organized seed savers store their seed collections in shoeboxes or cookie tins with a packet of silica desiccant and a spreadsheet detailing target sow-by dates. The rest of us keep packets of seeds on the dresser, by the washing machine, and in the kitchen junk drawer; we forget to sow them on time and are grateful when nature takes its course. The cookie tin method is great because you can store it where it will be subjected to temperature fluctuations (in the refrigerator if there’s room, or outside over the winter) which might help trick the seeds into germinating whenever we decide to sow them.
HEIRLOOMS, HYBRIDS, AND SEEDLESS GREATS
Thanks to nature and plant breeders, we can count on a sliding scale of predictability when it comes to the outward appearance of self-sowers. At the most predictable end are heirlooms: carefully selected open-pollinated plants that have been sowed and saved for at least half a century Although pollinating insects, birds, and wind are in control of open-pollinated plants, they will continue to look the same from one year to the next (aside from naturally occurring mutations) as long as different species haven’t been planted in close proximity. Or if we gardeners consciously choose to save seeds from the best plants and the showiest flowers, as is the case with heirlooms, our plants will actually improve over time.
Hybrids are somewhat less predictable. When wildlife and wind cross-pollinate different varieties of the same species of open-pollinated plants growing in close proximity, they create a new generation that is similar but slightly different from each parent plant. If you have two different varieties of flowering tobacco (Nicotiana) in your garden, the seeds from either could become a whole new variety—a hybrid—with either a fabulous or a strangely muddy mix of characteristics. Dominant and recessive gene variations, as well as naturally occurring mutations will always present surprises, good and bad. Sometimes it’s best to start all over again with the strain you prefer.
F1 hybrids, on the other hand, are bred by controlled cross-pollinating of two parent species with differing traits to achieve a particular union of extra-special characteristics. They have to be created over again each season from the same parent species. With flowers, breeders are usually trying to create a new color, better height, improved sturdiness, or longer bloom time. As awesome as F1 hybrids usually are, their seeds will either be sterile or their seedlings will revert back to a disappointing parental form.
Breeders have a few excellent reasons to deliberately develop sterile or seedless plants for gardeners too. One is to create non-invasive forms of those ornamental invasive species that we all love, like purple loosestrife and butterfly bush, by making them incapable of producing healthy, viable seeds. Those plants may still spread from the roots, but at least they won’t send seedlings far and wide as well. Another reason is to save gardeners the trouble of deadheading to prolong a plant’s bloom time. Usually, a plant that cannot set seed will continue to bloom its head off until seasonal cues, like low daylight or cold temperatures, tell it to quit. And occasionally seed production is sacrificed when the plant’s energy is spent on bigger flowers or extra petals instead. The only way for gardeners to propagate a plant that cannot self-sow is to take cuttings or divide it at the roots.
A fabulous russet sport in a patch of Nicotiana ‘Lime Green’.
Testing the viability of lupine seeds—only one sprouted.
Most hardy annual and perennial seeds ripen in the summer or fall and may be stored—dry, dark, and cool—for at least one season to keep them dormant until you decide to flick the switch. Seeds that ripen in the spring should be sown immediately after collection rather than saved for later because in order to germinate they are likely to need summer’s heat before winter’s chill. And because the seeds of most biennials will germinate as soon as they hit the ground, in order to give their seedlings a full season to grow before flowering the next, they should also be sown as soon as possible.
A seed’s lifespan also varies by species. Some will remain capable of germinating for years while others only survive dormancy for a season or two. To test whether old seeds are still viable, fold ten or so into a dampened paper towel placed inside a resealable plastic bag to keep the seeds moist, and place them where they will stay warm (about 70 degrees F), such as on top of the refrigerator. Check for sprouts after a week or two. If all seeds sprout, you win; if only one or two sprout, the germination rate will be low for the whole batch. Use your results to sow more (or less) seeds than you think you’ll ultimately need.
