The Physiology of Garden Love

When the days begin to warm, the gardener bides her time. Once the soil is also warm and the frost promises to hold off until fall, a new growing season can begin. The gardener wasn’t idle while her soil was frozen and covered in snow. She pored over seed catalogs and diagrammed the most efficient use of space or most beautiful arrangement of ornamentals. When only a few weeks remain before soil fully thaws, the gardener peels open fresh packets of seeds and tucks them into potting soil where they’ll become seedlings before braving the outdoors.

Seeds have thick protective coats housing an embryo inside that will eventually sprout to become roots and foliage. That protective coat prevents water from entering or exiting the seed and also limits its interaction with gases in the air. For a seed to sprout, it must shed the seed coat.

Tomatoes, kale, eggplant, leeks, broccoli, basil. Tasty recipes emerge from the soil, unbending their first stem as though letting out a slow yawn. Slowly, leaves take on their unique shape, texture, and scent. The gardener has anticipated the scent of fresh basil since plucking the last withered herbs in October. A tomato’s velvet stem reminds her of the supple fruit it will yield in July.

Temperature is crucial in shedding a seed coat. It isn’t simply that seeds need to be warmed, many seeds require warmer temperatures during the day and cooler temperatures at night. Holding a seed at a constantly warm temperature reduces germination rates and can lead to poor plant growth. Once a seed senses the proper temperature alternation, usually 5-10ºC difference between day and night, it sheds the seed coat and begins to interact with water, gases, and nutrients around it. Continue reading

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