Onions . Yes , light has something to do with onions . And I have teach that it had something to do with MY onions . There are so many varieties of onion — Vidal , Walla Walla , Texas Super Sweet , just to name a few . But for years the kind I longed to mature were the swelled Allium cepa . Man , I have tried , but have go to accomplish those softball - size of it bulb receive in the super market place and pictured in seed catalogs . I would even settle for a baseball game - size onion plant . The safe I could do was something between the size of a golf game ball and a lime , until I became cognizant of an essential environmental constituent : photoperiod . Here ’s how it chance .
After many years of attempting to grow those “ market size ” onion , I come to the unhappy finale that perhaps it was time to admit bankruptcy and to put that “ onion plant space ” in the garden to better use . Well , having been told on more than one function by my married woman that I was “ hard - head ” and just “ unembellished ole ’ stubborn , ” I calculate what the heck , just one more attempt . meanly , I did the manly thing and admitted a little inquiry was in parliamentary procedure if I was ever going to be able to arrogate the bragging right field for grow the large and ok onions in the neighborhood .
Living here in Central Virginia , by nature the first question that flashed across my mind was , “ I wonder howMr . Jefferson’sonioncropfared . ” A friend , knowing my interest in horticulture and account , recently gave me Peter Hatch ’s book , ARich Spot of Earth . I wondered if Mr. Jefferson had experience the same onion job as I. Maybe he had peeled back the proverbial onion and retrieve a solution I might apply to conclude my onion plant quandary . According to Mr. Hatch ,
“ In the South , onions ( Alliumcepa ) are a strong point item , grown in measure under specific experimental condition . Mid - Atlantic dwelling garden usually contain only ‘ green onions ’ or Allium porrum ( Allium fistulosum ) , especially because onions are so cheap in super market . Onions were recorded as being planted in the Monticello garden only nine times . Since onions were a staple fiber in some of Jefferson ’s favorite mantrap and were purchase twenty - one time from the Washington grocery in 1806 , one might conclude that Jefferson find other source for this age - quondam but prized culinary gem of the subterranean macrocosm . ” ( Hatch , p. 184 ) .
It appears that the onion planting at Monticello were limited to Egyptian walk onion . A little more about that subsequently , but for now , theMonticelloonion Revelation of Saint John the Divine was not much help in my pursuance for softball game - size of it Allium cepa .
My next research plosive consonant was theVirginia Tech Publication 426 - 411titled “ Onions , Garlic andShallots . ” Here are the environmental preferences of onions as listed in Pub . No . 426- 411 :
Having hunt down though the environmental checklist with vanish vividness , now what ? There must be something that I miss . A piffling humbled , I determine to do the unthinkable : I revisited the publication and proceeded to take whole thing . Well , you guessed it ; I had indeed missed something crucial . I learned that there are three unlike groups orcategoriesof onions : “ prospicient - day ” onions , “ short - daylight ” Allium cepa and “ intermediate - Clarence Shepard Day Jr. ” onions ( also call “ day neutral ” ) . What was that all about ? Hmmm , perhaps something to do withdaylight length ? This reminded me about that old thermos bottle story — it can keep stuff and nonsense stale or hot . How does it make out which to do ? You ’re right . A little more research was required .
Most onions , as it turns out , arebiennialplants , which is just a fancy way of suppose that it takes two ( 2 ) raise season to complete thelife cycle . In its first year , the onion plant plant develops and produces a bulb that is used for food storage , and in the following yr , it produces flowers and seeds . In myopic , onions have three ( 3 ) “ major ” phases of increase : thevegetative form , when ascendent and leaves are bring forth by the plant , thebulbing phasewhen bulbs are give rise , and thereproductive phase , when flowers and seeds are produce . The bulbing stage and flowering stage are usually dissever by a cold ( vernalization ) period . onion plant produce for their incandescent lamp are deal as annual and harvested at the closing of phase two ( 2 ) . The three distinct phase are drive bytemperatureandlength of twenty-four hour period , also known asphotoperiod . Since onion bulb development depends on the temperature and length of day , random planting during our growing season here in Virginia will leave in limited success .
Thesize of the onion plant lightbulb is dependent upon the number and size of the green leaf or transcend at the time of bulb matureness . For each leafage there will be a closed chain of Allium cepa ; the larger the folio , the larger the ring will be . The onion will first form the top , and then , bet on the onion plant variety and duration of twenty-four hour period , it will start to mould the bulb . ( Magruder ) . Herein lies the challenge : the requirement for foliage and foliage development and the requirements for bulb development aredifferent . Since the Allium cepa is a cool conditions crop , foliage exploitation take a temperature of 45 - 60º and light bulb formation postulate a temperature requirement of 60 - 75º foroptimum bulb size .
In addition to temperature , bulbing is initiated when the daytime length reaches the routine of hours vital for that assortment . In scant , temperature and day length are the factors that determine when vegetational growth catch ( phase 1 ) and bulb development ( stage 2 ) start out ( Lancaster ) . There have been attempts to isolate the trigger that move from folio growing to onion plant development , but these have been abortive . ( Remember that how - does - it - know thermos fib ? ) , but some research advise that hormones and growth regulators such as auxin , cytokinin , gibberellins , and ethene have been implicate in bulbing ( Brewster ) . However , research carry atTexas A&MandThe U.S. Department of Agricultureconcluded that no evidence could be found to support the claim that treating onion plant with growth governor and hormones increase the size or weight of onion bulb .
The selection of the correct varieties and planting time are vital for success . Choose a short - Clarence Shepard Day Jr. variety when day length is 11 - 12 hr ( latitudes less than 35 degrees ) ; choose intermediate - day types when 24-hour interval length outmatch 13 - 14 hours ( middle latitudes ) and think that prospicient - solar day types need greater that 16 hour of day , ( latitudes majuscule than 39 degree ) . ( Brewster ) . Our close together latitude in central Virginia is 38 degrees , so we just happen to be between the inadequate day and long day category . Our recollective day daytime is14 hours and 48 bit — obviously too little for prospicient - mean solar day onion . But wait , 14 hours is more than enough fourth dimension for short - day onions . But since the length of Clarence Shepard Day Jr. is what triggers bulb development , in our surface area that 12 - 60 minutes trigger is March 17 . That ’s because the size of the bulb depend on the top or foliation exploitation , and we do not usually reach the optimum temperature roam for that ( 45 - 65 degree ) until March 17 . That ’s just a roundabout way of saying that around here , the bulb starts to mold before there is sufficient leaf development to acquire a large onion plant medulla oblongata . In the fall it ’s just the opposite ; we have the right temperature for top ontogenesis but miss the 75 - 85 degree temperatures for adept medulla oblongata development . So cutting through all that mumbo jumbo , the orbit we live in is not ideal for growing short- or long - day onions . Therefore , we are special to intermediate - solar day onions . The chart below depicts the grow range of mountains for the various type of onions :
cum catalogs often provide the length of 24-hour interval requirements for the onions they offer , and in a few instances , supply information such as “ adaptation 35 degrees-45 degrees latitude . ” In short , to increase the probability of having a successful lightbulb onion crop in our area , one need to be cognisant of the class of onion that grows well here . In our expanse , forgetful - day and retentive - day onions will have circumscribed success , whereas the intermediate - day onion — such asCandy F1 , Candy ( Red ) F1 , Crystal , Gladstone or Super Star — will have greater success .
Many of these varieties are available from various seed catalogs as seeds or starts . If you want to begin onion indoors and transpose them to the garden , they need to be started in January . seedling or plants can be ordered from various catalogs . Several of our local garden centers often carry intermediate - day onion in the other spring .
In our area onion plants should be jell out as shortly as the priming is executable and up into mid - April . As for the bulk small onion plant bulbs ( labeled : yellow , white and red ) on cut-rate sale in garden center and big box stores or at our local computer hardware stores , their variety and length of sidereal day requirements are unknown ; however , if your finish is to grow bounce Allium cepa for their green foliage — not for a with child “ bulb ” onion — they will act upon in our area for that purpose .
Once I figured out all that long - twenty-four hour period , curt - 24-hour interval and intermediate - day stuff , the existent cultivation of onion was comparatively light . Va. Tech Publication 426 - 411offers elaborated educational activity on the cultivation requirements .
Wow , I commemorate that first softball candy onion I grew . I could n’t waitress to veer into that chump . Well , lease me tell you , I did n’t know I was adequate to of so many rent , and when I took a bite , it was unassailable . It plough out that onion have a defense mechanics ; when you cut in into an onion and damage the cellphone walls , it releases a compound calledSyn - propamethial flatulence , which is a sulfate derivative instrument . In general , Henry Clay soils and organic matter have a comparatively high level of sulfates ( Brewster ) . I have clay soil , which has been amended with constituent affair , which means that because of these gamey sulphate levels , I ’ll never be able to grow that mellifluous onion that can be eat like an Malus pumila .
Now the only matter left to figure out is when to glean the onions . As ageneral rulethe onion top side will turn slimly sensationalistic and “ diminish over . ” The onions should be reap soon after the crest have light over . Do n’t depart the onion bulbs in the dry land longer than a calendar week or two after they have fallen because the bend in the onion husk is a light point and can provide a roadway for organisms to enter the plant . These organisms may get the Allium cepa to rot untimely . Naturally onion may be harvest before they fall over to be used fresh in the kitchen . Also , medium - day onions are not considered long warehousing onions or estimable keeper , and my experience is they can be stored for 3 - 4 month before they begin to go sorry .
Now back toMr . JeffersonandMonticello . What is now be intimate about photoperiod and its shock on onions had not yet been discovered in Jefferson ’s time . That did n’t happen until1920 . Therefore , the grandness of select the right duration of day change may have been an unknown in Jefferson ’s Clarence Shepard Day Jr. . In addition , the soil at Monticello is clay , and in all chance has a in high spirits sulfur depicted object , which will increase the pungency of the onions , and may have led to the percept that “ northern ” onion plant were scented and of well quality . Or it may be , as Mr. Hatch suggests in his book , bulb onions were so meretricious that the space in the vegetable garden at Monticello could be put to better use .
In sum-up , onion are a nerveless weather crop . The exploitation and size of an onion bulb is subordinate on two environmental factors : temperature and length of day . There are three ( 3 ) category of onions : poor - daytime , medium - day ( or day - neutral ) and long - day . In Central Virginia , because of our location we can look to be successful with the selection of an medium - day type onion such asCandy F1 .
The heat or pungency in an Allium cepa is directly correlated to the level of sulfur in the soil ; therefore , because our clay soils have a tendency to have moderately high levels of sulphur , one would look the onions we raise to be on the pungent or hot side . I was pleasantly surprised at how successful I was when growing the intermediate - day case onion plant , and hopefully you too will be successful .
character :
Hatch , Peter J.,A Rich Spot of dry land : Thomas Jefferson ’s Revolutionary Garden at Monticello , Yale University Press , ( 2012 ) .
Brewster , James L.,Onions and Other Vegetable Alliums , 2nd ed . ( 2008 )
Magruder , R. , R.E. Webster , H.A. Jones , T.E. Randall , G.B. Snyder , H.D. Brown , L.R. Hawthorn , and A.L. Wilson , Description of Types of Principle American Varieties of Onion , Miscellaneous Publication 435 USDA , Washington D.C. ( 1941).http://usdasearch.usda.gov / search?utf8= ✓ &sc=0&query = WEBSTER+MAGRUDER+PUBLICATION+435&m=&affiliate = usda&commit = lookup
Garner , W.W. and H.A. Allard , “ force of comparative length of day and night and other factors of the environment on ontogeny and reproduction in Plants,”Journal OfAgricultural Research 18553 - 606 ( 1920 ) .
http://usdasearch.usda.gov/search?utf8=✓&affiliate=usda&query=VOL+XVIII+MARCH+1920+NO+11&x=19&y=14&commit=Search
The National Onion Association , http://www.onions - usa.org/
