Explore Plants
Ask Mr. Smarty Plants
Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
rate this answer
Wednesday - November 22, 2006
From: Leander, TX
Region: Southwest
Topic: Propagation
Title: Breaking dormancy of native seeds
Answered by: Nan Hampton
QUESTION:
The science of seed preservation seems to be well advanced. However, Jill Nokes' book appears to be the only well-known information about breaking dormancy of native seeds. I'm grateful that she wrote that book, but it is more of a anecdotal collection than a scientific study, so I would appreciate any further sources of information that you encounter. If you can answer, or forward this question to the appropriate person, I would certainly appreciate it: Is stratification, either warm or cold, a biological process that requires imbibation in order to proceed? In other words, should a seed be scarified BEFORE stratification? This is confusing to me because all texts seem to treat storage SEPARATELY from preparation for germination, while in nature it's all one complex, variable process. Obviously, since my objective is to propagate, I need to perform specific actions at specific times to replicate the "natural" requirements of a species. More than you expected, I guess........, but thanks for any help.ANSWER:
Seeds with tough impermeable coverings need a break in that seed coat in order to allow moisture to enter to begin the germination process. Seed scarification occurs naturally from environmental sources—abrasion from the soil, frost, fire, passing through the digestive system of animals, etc.—but this is more or less a random process. We can intervene and speed up the process by scarifying batches of these tough-coated seeds before they are planted. There are several methods: mechanical—abrading by sandpaper, knife, etc.; soaking in water; and treating with acid. Stratification, either cold or warm, involves storing the seeds in a moist medium, such as sand, for a period of time to break the physiological dormancy. Indeed, seeds with tough coats need to be scarified before stratification so that they can take advantage of the moisture in the stratification medium. Several studies have reported both increased speed and amount of germination by scarifying and then stratifying seeds. For example:Kaye, T. N. "Effects of scarification and cold stratification on seed germination of Lupinus sulphureus ssp. kincaidii." Seed Science and Technology (2001), v. 29(3), p. 663-668. A combination of scarification and stratification increased germination by as much 95%.
Syn,. Y. C. et al. "NaOH scarification and stratification improve germination of Iris lactea var. chinenesis." HortScience (2006 June) v. 41(3), p. 773-774. Germination improved by 80% using both treatments together.
Geneve, R. L. "Seed dormancy in Eastern redbud (Cercis canadensis)." (Jan. 1991), v. 116(1), p. 85-88. From the abstract: "Seed dormancy in Eastern redbud (Cercis canadensis var. canadensis L.) can be overcome by seedcoat scarification to allow water imbibition, followed by chilling stratification to permit germination."
Qrunfleh, M. M. "Studies on the hawthorn (Crataegus azarolus L.): I. Seed germination as influenced by scarification and stratification." Dirasat Series B Pure and Applied Sciences (1993) v. 19(4), p. 7-18. Acid scarification combined with warm stratification increased germination by 10%.
Stratification requirements and techniques differ for various plants and some do not benefit particularly from stratification. However, if the seeds would benefit from stratification, either cold or warm, and they have an impermeable coat, the bottom line would seem to be scarify first and then follow with stratification.
You can find a good article on seed germination and dormancy from Texas Tech University Department of Plant and Soil Science.
More Propagation Questions
Transplanting Mexican bonebract in Floresville, TX
November 12, 2008 - My kids and I finally identified a small plant that we found growing in our pasture. There was only one and it is lovely. It is the Mexican Bonebract. What I am interested in finding out is how to tra...
view the full question and answer
Propagation of Jack in the Pulpit in Lansing MI
April 18, 2010 - I just received some Jack in The Pulpit corms. Which way is up; does the pointy thing go up or down?
Thank you.
view the full question and answer
Grooming and propagation of Bee Balm
August 28, 2007 - I planted our first Bee Balm [Mornarda didyma] bush a month ago. I`ve watered it daily and it is growing well with many runners apparent. Should I be deheading or pinching regularly? Should I cut it ...
view the full question and answer
Failure to bloom of Turk's cap in Midland TX
September 08, 2009 - My turk's cap won't make flowers. It has daily watering via irrigation system, and soft amended soil. The plant is beautiful and thriving, but no flowers. What should I do?
view the full question and answer
Propagation of lilies by seed
November 02, 2007 - I have collected a large number of lily seeds. How can I get them to grow?
view the full question and answer
 |
Support the Wildflower Center by Donating Online or Becoming a Member today. Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends. |
