The saga of seeds

Seeds are critical to human survival. They supply us with food, fiber, shelter and aesthetic pleasure.

These amazing structures are miniature survival packages, storing sufficient carbohydrates to support their own germination and early growth. Their chemical and physiological makeup allows them to lie dormant until the conditions are right for germination, even after separation from the parent plant. Some seeds may remain dormant for decades. However, since most seeds gardeners work with lose viability the longer they remain dormant, expiration dates are usually printed on packets of vegetable and flower seeds.

Seeds require certain conditions to germinate. Water is essential. Once sufficient water is supplied to a seed, germination begins. However, very dry seeds need to absorb water slowly or tissue damage and possible death of the embryo can result. Soaking seeds before sowing might actually destroy these types of seeds, even though this is an age-old gardening practice. Many seeds need water and then light to germinate. Once sowed, they need to be barely covered with soil, or they won't grow. Temperature is another important consideration for germination. There is an optimum range of low to high temperatures that varies from one kind of seed to another.

A critical factor in seed success is dormancy. Seed dormancy can greatly reduce germination. Some seeds will not germinate no matter how much water they receive or what the temperature is. They need very specific conditions to break dormancy. Other seeds, such as beet seeds, have chemical inhibitors that must be leached out before germination can occur.

Many seeds require a specific cold-temperature treatment for a certain length of time to break dormancy. This process is called cold stratification. Some seeds, such as peas and beans, have hard seed coats that present a barrier to water. These seeds need abrasion or seed scarification on the seed coat to allow water to penetrate. Repeated wetting and drying, chipping, rolling the seeds around on sand paper or treating with microorganisms are ways to scarify hard seed coats. Several plants require exposure to fire to germinate. Some particularly difficult seeds require a combination of treatments to break dormancy.

Finally, a strong, healthy parent plant of high-quality genetic stock usually produces seeds of the best vigor. Weather conditions during ripening can also affect seed strength. Appropriate seed storage is another important factor in successful seed germination.

For more information on seed germination, you can refer to "Science and the Garden - the Scientific Basis of Horticultural Practice," edited by D. Ingram, D. Vince-Prue and P. Gregory.

Or, for more information on this and other gardening topics, contact me, 887-2252 or skellyj@unce.unr.edu, or your local University of Nevada Cooperative Extension office. Check out many useful horticulture publications at www.unce.unr.edu. "Ask a Master Gardener" by e-mailing mastegardeners@unce.unr.edu.

JoAnne Skelly is the Carson City / Storey County Extension Educator for University of Nevada Cooperative Extension. (Brand names are used for illustration purposes only and do not constitute an endorsement by Cooperative Extension.)