Sunday, March 2, 2014

Early Planting: Is there enough light?

Yesterday I mentioned that in order to have a 12 month garden, your plants have to have both enough warmth and enough light.    There are loads of vegetables that are comfortable in cool weather, but the light issue is more universal.

It all has to do with the number of hours of light in a day - and that depends on your latitude.  Plants grow well when they get at least 10 hours of daylight a day.  The further away from the equator you get, the more days below 10 hours you'll get during the times of year that your pole is pointed away from the sun - November through March in the northern hemisphere,  April through August in the southern hemisphere.    The exact number depends on your latitude - how far away from the equator you are.

I was thinking how nice it would be if there were a chart out there on the interwebs with all this information for every latitude and it turns out there is!    Yay!   

And thanks to the  U.S. Navy, there's a site with a handy dandy calculator that spits your information out for you and you don't even have to know your latitude!    You just have to know where you are.   [If you don't already know where you are, I'm sure there's someone close by you can ask.]

Go here:  http://aa.usno.navy.mil/data/docs/Dur_OneYear.php   and fill in Form A.   [If you live outside the U.S., fill in Form B.]   You can choose a different year if you want.   Notice below the forms that there are directions for saving it to a spreadsheet.  

Turns out that Solsberry is too small to be listed, so I used Bloomington for my location.   Here's the daylight chart  for Bloomington, Indiana.  [Sorry for the tiny type - it's the only way I could make it fit.  The files don't convert to pic files.]

              o  ,    o  ,                   BLOOMINGTON, INDIANA                Astronomical Applications Dept.
 Location: W086 35, N39 13                   Eastern Standard Time               U. S. Naval Observatory        
                                                                                 Washington, DC  20392-5420     
                                                                                                                
                                         Duration of Daylight for 2014                                          
                                                                                                                
 Day    Jan.     Feb.     Mar.     Apr.     May      June     July     Aug.     Sep.     Oct.     Nov.     Dec. 
                                                                                                                
         h  m     h  m     h  m     h  m     h  m     h  m     h  m     h  m     h  m     h  m     h  m     h  m
 01     09:28    10:14    11:20    12:39    13:52    14:45    14:53    14:11    13:02    11:46    10:31    09:37
 02     09:29    10:16    11:22    12:42    13:54    14:46    14:52    14:10    13:00    11:44    10:29    09:36
 03     09:30    10:18    11:25    12:44    13:56    14:47    14:51    14:08    12:57    11:41    10:27    09:35
 04     09:31    10:20    11:28    12:47    13:58    14:48    14:51    14:06    12:55    11:39    10:25    09:34
 05     09:32    10:23    11:30    12:49    14:00    14:49    14:50    14:04    12:52    11:36    10:22    09:33
 06     09:33    10:25    11:33    12:52    14:02    14:50    14:49    14:02    12:50    11:34    10:20    09:32
 07     09:34    10:27    11:35    12:54    14:04    14:50    14:48    13:59    12:47    11:31    10:18    09:31
 08     09:35    10:29    11:38    12:57    14:06    14:51    14:47    13:57    12:45    11:29    10:16    09:30
 09     09:36    10:31    11:40    13:00    14:08    14:52    14:46    13:55    12:42    11:26    10:14    09:29
 10     09:37    10:34    11:43    13:02    14:10    14:52    14:45    13:53    12:40    11:24    10:12    09:28
 11     09:38    10:36    11:45    13:04    14:12    14:53    14:44    13:51    12:37    11:21    10:10    09:28
 12     09:39    10:38    11:48    13:07    14:14    14:54    14:43    13:49    12:35    11:19    10:08    09:27
 13     09:41    10:41    11:51    13:09    14:16    14:54    14:42    13:47    12:32    11:16    10:06    09:27
 14     09:42    10:43    11:53    13:12    14:18    14:54    14:41    13:44    12:30    11:14    10:04    09:26
 15     09:44    10:45    11:56    13:14    14:20    14:55    14:39    13:42    12:27    11:11    10:02    09:26
 16     09:45    10:48    11:58    13:17    14:22    14:55    14:38    13:40    12:25    11:09    10:00    09:25
 17     09:47    10:50    12:01    13:19    14:23    14:55    14:37    13:38    12:22    11:07    09:58    09:25
 18     09:48    10:53    12:03    13:22    14:25    14:56    14:35    13:35    12:19    11:04    09:57    09:25
 19     09:50    10:55    12:06    13:24    14:27    14:56    14:34    13:33    12:17    11:02    09:55    09:25
 20     09:51    10:57    12:09    13:26    14:28    14:56    14:32    13:31    12:14    10:59    09:53    09:25
 21     09:53    11:00    12:11    13:29    14:30    14:56    14:31    13:28    12:12    10:57    09:51    09:25
 22     09:55    11:02    12:14    13:31    14:31    14:56    14:29    13:26    12:09    10:54    09:50    09:25
 23     09:57    11:05    12:16    13:33    14:33    14:56    14:28    13:24    12:07    10:52    09:48    09:25
 24     09:58    11:07    12:19    13:36    14:35    14:55    14:26    13:21    12:04    10:50    09:47    09:25
 25     10:00    11:10    12:21    13:38    14:36    14:55    14:24    13:19    12:02    10:47    09:45    09:25
 26     10:02    11:12    12:24    13:40    14:37    14:55    14:22    13:17    11:59    10:45    09:44    09:25
 27     10:04    11:15    12:27    13:43    14:39    14:55    14:21    13:14    11:57    10:43    09:42    09:26
 28     10:06    11:17    12:29    13:45    14:40    14:54    14:19    13:12    11:54    10:40    09:41    09:26
 29     10:08             12:32    13:47    14:41    14:54    14:17    13:09    11:52    10:38    09:40    09:26
 30     10:10             12:34    13:49    14:42    14:53    14:15    13:07    11:49    10:36    09:38    09:27
 31     10:12             12:37             14:44             14:13    13:04             10:33             09:28 
 

Notice that the latitude is in the top left corner of the chart.   The location and year are top center. 

For Bloomington,  the first time we get at least 10 hours a day this year, 2014, is January 25.    The last day we'll get at least 10 hours of daylight a day is November 16.  

That means our growing season lasts from January 25, to November 16.   That is a lot of days!    As long as we plant vegetables during the times of year that have the temperatures they like, then we can grow a lot of food here.

I've said before that we have a 12 month garden.   How does that work when we're getting less than 10 hours of light per day [Nov 16 - Jan 25]?   We'll  talk about that tomorrow.


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