Earlier this summer , a generous neighbor gave me some columbine ( Aquilegia ) seeds from her beautiful garden . Naturally , I was thrilled to receive the come but was n’t indisputable when to plant them . Some horticulture source notify planting them in other spring . Other sources recommended plant them in spill . So , which was correct – give or fall ? While the author take issue on when to plant the seeds , they were coherent on one peak : Columbine seed need to be exposed to a time period of cold temperatures before they canbreak dormancy . But why ?
First — What does it mean to break dormancy ?
Seeds may appear lifeless , but that is not the case at all . essentially , a semen is a plant in embryonic shape enclosed in a protective masking ( seed coat ) . The heaviness and hardness of the cum coat combined with chemical sprouting inhibitors ( internal secretion ) within the seed pelage protect the embryonic plant until conditions are optimal for sprouting . Tobreak dormancysimply means that the embryotic works must literally break through or break away the seed coat so that germination can take position . For that to befall with some plant species , the seed coat require to be mince or weakened through a process calledstratification .
social stratification
Stratification apply temperature to break in dormancy . It go on when dormant seeds are exposed to a catamenia of stale temperature followed by warm temperatures and wet . This combination of understudy temperatures softens or weakens the ejaculate coat allowing the semen to germinateonce growing conditions are suitable in spring . Think of stratification as a survival mechanism that prevents seeds from germinating either too too soon in spring , when the cutter seedlings might pass during a late inhuman snap fastener , or too recent in summer when they wo n’t live long enough to produce new seed . This mechanism put on to plants that develop in temperate climates such as those found in North America . Plants species that evolved in raging climates , such as the Torrid Zone , do n’t experience inhuman temperatures . Therefore , the seeds of those species do n’t demand to be stratified .
For seeds that fall to the ground from works or are sow in in late summer or fall , social stratification come of course during winter ’s freeze / thaw hertz . This method has worked for Mother Nature for hundreds of yard of years . But seeds may also be stratify indoors for planting outdoors later . The key to achieving successful social stratification indoors is to simulate the conditions seeds experience when break dormancy in nature . In other words , the goal is to trick ejaculate into thought they have experienced winter .
Methods for stratify Seeds
Before stratifying seeds , research the amount of chill time they require to break dormancy . It can range from just a duet of weeks to many months , depending on the flora species . Then , decide which social stratification method will work well . While there are many method , a few of the easier ones are account below . In increase , check out some of the commercial-grade nursery web site for step - by - step social stratification instructions and pall times .
Dry Stratification – This is a pre - discussion that subjects cum to a catamenia of cold-blooded temperatures without any wet . It crop well for plants such as cleome , foxglove , some poppy species , and hardy perennial Grass that fly high in juiceless soils or ironic winters . Simply seal off wry cum in a credit card baggie or looking glass jar , label and date the contents , and store the container in the icebox for one to four months depend on the plant species . After the chilling menstruation , take away the seeds and industrial plant in spring as you ordinarily would once the danger of rime is past .
Moist Stratification – This method requires seeds to be in contact with a moisture - retaining medium during the chilling procedure . It function well for plants , such as wildflower mintage , that evolve under moist , stale winter condition . Those conditions can be mimic using any of the moist stratification method acting below :
Baptisia seeds prepared for cold , moist social stratification . photograph : Pat Chadwick
Examples of seeds that benefit from stratification
Seeds of most Sir Herbert Beerbohm Tree and shrub species that germinate in the mid - Atlantic orbit of the U.S. welfare from stratification . The amount of chilling metre needed look on the species . Iowa State University Extension ’s publication onGermination of Tree Seedprovides advice on when and how to collect Sir Herbert Beerbohm Tree source for sprouting of a variety of species let in redbuds , maples , oaks , hickories and fruit trees .
The seeds of most cosmetic yearly species do n’t require social stratification . However , a few that do require stratification admit larkspur ( Consolida ) , beloved - in - a - mist ( Nigella ) , yearly poppy ( Papaverspp . ) , annual pincushion flower ( Scabiosa atropurpurea ) , and bells of Ireland ( Moluccella laevis ) .
A few examples of perennial coinage that benefit from social stratification include :
contraband - eyed Susan ( Rudbeckiaspecies )
Columbine ( Aquilegia )
False Aster ( Boltonia )
False Indigo ( Baptisia )
False Sunflower ( Heliopsis )
Ironweed ( Vernonia )
Joe Pye Weed ( genus Eupatorium maculatum )
Lavender ( Lavendula )
Milkweed ( Asclepias syriaca )
New England Aster ( Symphyotrichum nova - angliae )
Perennial Sunflower ( Helianthusspecies )
Rattlesnake Master ( Eryngium yuccifolium )
Turtlehead ( Chelonia )
In finicky , wildflower specie that produce their seeds in fall benefit from stratification . For more information on those species , hold in out the Missouri Botanical Garden ’s steering on Native Seed Propagation Methods listed under source at the goal of this article .
Scarification
Some seed may not shoot if wet can not penetrate their laborious , impermeable seed coats . Those seminal fluid should be scarified before they are stratified . Scarificationis the process of breaking , scratching , or softening the seed coat so that wet can get through and start the germination process . While this process often can be accomplished through natural means , it can also be accomplished by mechanical , chemic , or thermic intervention such as :
The germ of many tree specie do good from a compounding of scarification and stratification because of their particularly heavyset , concentrated seed coats . Virginia Cooperative Extension ’s Publication 426 - 001 abstract basicseed stratificationprocedures for trees and shrubs .
In closing
Seeds of many flora species that evolve in temperate climates require a period of frost / thaw temperatures to wear dormancy and germinate . By understanding how seed make in term of social stratification and scarification , it ’s potential to better their sprouting rate .
As for the columbine seminal fluid mention at the beginning of this clause , sources vary on the amount of time they should be stratified with the fair time being 3 to 4 weeks . This intend they may be planted out of doors either in early bound before the land warms up or in fall so that they are exposed to the wintertime cold . As long as the seeds receive sufficient chill sentence , either approach path will exercise .
FEATURE PHOTO : Examples of seeds that benefit from social stratification . Starting at top of photo and moving clockwise : Baptisia , milkweed , coneflower , cover flower , coreopsis , and columbine . Photo : Pat Chadwick
SOURCES :
Plant Propagation , The American Horticultural Society ( Toogood , Alan , 1999 )
Botany for Gardeners , Third Edition ( Capon , Brian , 2010 )
The Ever Curious Gardener – Using a Little Natural Science for a Much adept Garden(Reich , Lee , 2018 )
Germination of Tree Seed , Iowa State University Extension
How to Prepare Seeds for Sowing , Lady Bird Johnson Wildflower Center
Native Plant Seed Propagation , Rutgers Cooperative Extension Fact Sheet FS1329
Native Seed Propagation Methods , Missouri Botanical Gardens
Plant Propagation From Seed , Virginia Cooperative Extension publication 426 - 001
Seed Stratification : What Seeds Require Cold Treatment ? , University of Illinois Urbana - Champaign Extension
