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The Magic Is Gone: Why Seeds Don’t Sprout

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Waiting and then more waiting. A hunched gardener, surrounded by small containers of moistened soil material, searches for any evidence of a sprout. What happened to the hopes and dreams of summer bounty? Time, money, electricity, seeds, soil, water, and more are all betting on the future of seedlings. Yet they have not emerged to face the world. Why have they refused to germinate?

What causes germination magic to stop? Seeds need water, air, heat, light, and basic health to get started.

The quickest way to stop seed germination is with watering techniques. Water softens the seed coat so the root will emerge; it mixes to form nutrition for the seed, and serves as the “motor down the highway” to move hormones and nutrition up and down the germinated seed. If you overwater, the seed drowns and rots. Too much water in your planting material creates a lack of air spaces for root growth and kills helpful soil bacteria. All seeds, even dormant ones, survive by respiration. They absorb oxygen and release carbon dioxide. If your soil is too heavy and waterlogged, the seeds will not perform and the Seed Planter will be left staring at little containers of wet soil. Just remember, not too wet or not too dry. Like Goldilocks and the three bears.

Heat, or lack of, is problematic for seed germination. Different seeds have different requirements. The germination temperature range for seeds started indoors is 75 to 90 degrees. Lower temperatures may slow germination; cold means the seeds will stall out. If it is too hot the seeds cook. Again, remember Goldilocks.

Seeds themselves may halt germination. Some seeds have a Superman-impermeable coating that requires assistance from the Seed Planter to break. Scarification is using a file, or something rough, to break the hard coating. Some seeds are chemically dormant, with Mother Nature halting germination using abscisic acid (ABA). One method to break down chemical dormancy is by refrigeration. These conditions should be clearly stated on the seed package.

Planting techniques may grind germination to a fast halt. Seeds planted too deeply will simply run out of gas before they get to the surface. Some seeds, like begonias and petunias, need light to germinate. Pushing them into deep soil will stop germination dead.

Some seeds are just no longer viable. With age or poor storage conditions, stored in high heat or high humidity, seeds will not come up. Seeds are composed of 20% moisture and 80% growing tissue. Even in dormancy they conduct respiration, so age may disrupt cells and growth hormones stopping viability.

Light goes hand in hand with darkness. In light, the plant manufactures sugars and starches. Darkness allows the plant to digest and use those components to grow. Provide your germinating seeds with at least 8 hours of darkness daily.

Using the Goldilocks rule will help your seeds to germinate. Not too hot, not too cold. Not too old, not too hard. Not too saturated, not too dry. Not too deep, not too shallow. Use your seed packet information as a magician’s guide to perform all your planting tricks.

Julie Silva is a University of California Cooperative Extension Master Gardener of Tuolumne County who believes it is always good to be prepared.