Documents relating to Seed Cleaning
Author: Stasie Maxwell
Date: December 20th, 2022
The Understory Initiative’s winter 2022 newsletter and impact report. This report highlights our accomplishments in 2022, the impacts we’re having on understory habitats and local communities.
Download: TUI Winter 2022 Newsletter & Impact Report (.pdf; 15.5 MB)
Author: The Xerces Society Date: 2016
Native wildflowers are the backbone of pollinator habitat on the farm. Field borders, filter strips, pastures, hedgerows, and other places where wildflowers (and grasses!) grow also provide us with natural pest control by sustaining predators of crop pests. Additionally, these plants help filter runoff from fields, and protect soil from erosion. Despite the benefits that native wildflowers and grasses provide, the cost of seed can be daunting. Fortunately, if you have native plant areas already established, they can provide you with a readily available source for additional seed.
While harvesting seed from existing wildflowers around the farm may not yield huge volumes, it can provide you with the raw material to gradually create more habitat on the farm. By collecting seed from plants already growing on your land, you are also focusing your efforts on species that are known to perform well on your soils. In this document we outline the basic steps of collecting native plant seed using readily available, non-specialized equipment. While our focus is primarily on wildflowers, many of these same techniques can be useful for collecting native grasses as well as seeds from trees and shrubs.
Download PDF: Collecting and Using Your Own Wildflower Seed to Expand Pollinator Habitat on Farms (2MB)
Authors: Bonner, F.T. and Karrfalt R.P. (eds.) Date: 2008
The major audience for this book, as for its two predecessors, is those who are involved in the growing and planting of trees and shrubs. Their involvement can be collection and sale of seeds, production of nursery stock (both bare- root and container), or planting itself. Planting for commercial forest production is the traditional mainstay of tree planting, but planting for wildlife food, watershed protection, urban environmental improvement, ornamental enhancement, wetland mitigation, and carbon sequestration are all on the increase. Ecosystem management, now commonly used in the management of many federal and other governmental forest lands, has decreased the use of planting to regenerate the forests and has increased the role of natural regeneration. Those who apply these practices will find this book useful also in the data on flowering and seed production. Although the book is not intended to be a detailed textbook on seed ecology and physiology, there is sufficient scope and depth to the material included to make it useful to anyone who studies seeds.
Download (PDF): The Woody Plant Seed Manual (21MB)
Authors: Guerrant Jr., E.O. and Raven, A.
Seeds of 69 taxa native to the Willamette Valley, Oregon were subjected to four germination treatments: two under ambient late winter into summer environmental conditions (untreated (fresh) seed or dry and frozen seed) and two in controlled environment chambers (some seed was cold stratified at 5°C then placed in a 10°C/20°C chamber, other seed was placed in 10°C/20°C chamber then moved to a 5°C/15°C chamber). At least 93% of the taxa tested can tolerate desiccation and frozen storage.
One third of the taxa had a maximum mean germination above 80% in at least one of the four germination treatments, 55% of the taxa had a maximum mean germination rate between 10% and 80%, and only 12 % of the taxa had less than 10% germination. A total of 88% of the taxa had their highest germination in one or both of the two treatments, fresh and cold stratification.
Download (PDF): Seed Germination and Storability Studies of 69 Plant Taxa Native to the Willamette Valley Wet Prairie (267KB)
Author: Steinfeld, D.
J. Herbert Stone Nursery produces over 20,000 pounds of native grass seed annually from 36 species endemic to public lands in the western states. Nursery seedbeds are established from wild seed collections. Each collection (referred to as seedlot) is grown separately from other seedlots of same species to prevent cross pollen contamination. Sowing, culturing, harvesting and storage practices for seed and seedling production are discussed. Methods and strategies for achieving successful restoration projects using native grass seed and seedlings are also addressed.
Download (PDF): Propagating Native Grass Seed and Seedlings (202KB)
Authors: Justice, O.L. & Bass, L.N. Date: 1978
Details different methods of seed storage, different types of seed storage structures, temperature control methods, packaging materials, monitoring methods, and more.
Download (PDF): Principles and Practices of Seed Storage (11MB)
Authors: Harrington C.A., Lodding, C.C., and Kraft J.M. Date: 1999
Pacific madrone (Arbutus menziesii) seeds can be extracted and cleaned in a procedure which utilizes a mortar and pestle, a blender with a rubber blade, and several sieves. The method involves several steps but is not difficult and can result in a large amount of seed in a short period of time. Following extraction, the seeds can be dried and stored at low moisture content (6%) in sealed containers at 3-5°C or given a cold strati cation treatment and then sown. Cold stratification periods of 60 days or longer increased the initial rate of germination compared to seeds stratified for 40 days but resulted in seed losses due to premature germination during stratification. For lots from the Puget Sound Lowlands, cold stratification for 40 days is adequate; seeds in stratification longer than 40 days should be monitored closely for premature germination.
Download (PDF): Extraction and Germination of Pacific Madrone Seed (150KB)
Authors: Elias, S. & Garay, A. Date: 2004
The TZ test, one of the most significant discoveries in seed testing in the 20th century, provides an answer. It determines the percentage of viable seeds within a sample, even if seeds are dormant. This is particularly useful for freshly harvested seeds that possess high levels of dormancy such as some grasses and native species. The results of the TZ test indicate the amount of viable seeds in a sample that are capable of producing normal plants under suitable germination conditions.
Download (PDF): Tetrazolium Test: a fast, reliable test to determine seed viability (241KB)
Author: McCormack, J.H. Date: 2010
Principles and practices of seed harvesting, processing, and storage: an organic seed production manual for seed growers in the Mid-Atlantic and Southern U.S.
Download (PDF): Seed Processing and Storage (2MB)
Author: Tucson Plant Materials Center Date: 2004
Details information on seed certification, site selection and preparation, weed control, diseases and insects, seed harvesting, processing native seed, and seed production guidelines on a few specific native plants.
Download (PDF): Native Seed Production (899KB)
Author: USDA Date: 1968
Details seed cleaning techniques, seed cleaners and separators, conditioning and treatments, handling and storing, and plant layout.
Download (PDF): Mechanical Seed Cleaning and Handling, Agricultural Handbook No.354 (10MB)
Author: Rancho Santa Ana Botanic Garden Date: 2009
This manual focuses on the seed processing steps that precede – and are necessary for – successful propagation and long-term seed storage. It targets California native plants and plants native to northern Baja California, Mexico, but the general techniques are applicable also to other physiologically or taxonomically related species.
Download (PDF): Processing Seed of California Native Plants RSABC (14.8MB)