In the Garden:
New England
April, 2007
Regional Report

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Mimic conditions in nature to get your seeds off to the best start.

Persnickety Seeds

Nature seems to have been feeling playful when she programmed some seeds to require light, some darkness, some cool temperatures, some warm temperatures, some a soaking in water. Of course, it all has to do with the native habitat of the species and its adaptations for survival.

Knowing the germination requirements of the plants that we're starting from seed, as well as tips for speeding things along, can ease frustration (such as waiting months for lisianthus to form flower buds) and increase our success with seed starting. So you don't do like I did years ago and plant half a flat of lupines that need a germination temperature of 55 to 65 degrees, and the rest of the flat with purple coneflowers that need 70 to 75 degrees. So you know that snapdragons will germinate faster if you slip the pots of newly planted seeds into the refrigerator for a couple of days.

Give Them Light
Poppies (Papaver species) are one of the easiest seeds to sow because all you have to do is sprinkle them on top of the soil. No covering needed. They are one of the many seeds that need light for germination. Lightly pressing them into the soil will ensure that the seeds make contact so they will be able to draw moisture from the soil, even though when nature spreads the seeds no one is giving them a gentle pat. In our region early spring is a good time to sow poppy seeds, but they will germinate best when the soil temperature reaches 60 degrees.

Ageratum, coleus, cosmos, four-o'clocks, foxgloves, hollyhocks, nicotiana, petunias, salvia, stocks, strawflowers, and yarrow also need light, whether you start them indoors or in the ground. Lettuce is one of the few vegetables that need light for germination. Often the seed packet will have this information but not always.

In the Dark
Most seeds need a covering of soil for best germination. In general, the larger the seed, the thicker the covering -- or the deeper they need to be sown. A rule of thumb is to plant at a depth that's three times the thickness of the seed.

A Warm Bath
Fat seeds and those with hard seed coats, such as beans, peas, lupines, morning glories, and sweet peas, benefit from a soaking before sowing so the seed coats can begin to loosen and take in water. Beet seeds also benefit from soaking because their seed coats contain a germination inhibitor that needs to be dissolved.

Soaking isn't a necessary step but it can help keep the seeds from rotting in the cold ground before they have taken up enough water to germinate. Place seeds in a glass of warm water overnight, but no longer or the seeds may begin to get slimy and rot. Beans can split if soaked too long so remove the seeds after 1 or 2 hours. Morning glories have such a hard seed coat that one more step is helpful: scarification. Details follow.

Scarifying
"Nicking" or "scarifying" is a way of creating an opening in a hard seed coat so water can penetrate to promote germination. I read that some seeds (which ones, I wonder) require the use of a hacksaw -- seriously -- but a nail file or nail clippers will do the trick in most cases. Morning glory, lupine, and mallow seeds benefit from this treatment. File each seed until a tiny portion of the outer hard seed coat is removed, or use nail clippers to just barely cut through the seed coat on one end. A very tiny opening is all that's needed, you don't want to damage the embryo inside. Then soak seeds overnight before planting.

The Cold Treatment
Seeds of many temperate native plants and tree species as well as some commonly grown perennials need a cold treatment -- called "stratification" -- before they will germinate. In the wild, this protective mechanism keeps them from bursting into growth before winter is over. So we need to imitate winter in order to coax these seeds into growing. Pansies, bleeding hearts, columbines, daylilies, lavender, perennial phlox, and primroses are some plants that we need to try to fool into thinking they've had a wintry nap.

After soaking the seeds overnight in warm water, sow small seeds in pots of moistened (not soaking wet) vermiculite and slip each pot into a plastic bag. Tie bags closed and label them, then place the pots in the refrigerator. Large seeds, which can be more easily separated from the medium and potted up once chilled, can be placed directly in plastic bags containing moist vermiculite. Chill for the recommended length of time -- from two weeks to several months, depending on the type of plant. For example, daylilies need six weeks, columbines need three, pansies need two.

Once you remove the pots from the frig, let them warm up overnight at room temperature before you place them on a heat mat if you use one.

Far from being dissuaded from trying to start plants that have particular requirements, I find it reassuring to know how to coax them to sprout. Although I do draw the line at seeds that rely on smoke or fire to initiate growth.


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