Sunday, January 27, 2013

When To Harvest

Harvesting Schedule … how’s our wheat coming along?

Not very long into the road trip, the voice from the back seat asks, “Are we there yet?”   We apprentice small grain growers also want to know:  “Is it grain yet?”

More than impatience prompts the question.  Research suggests there are optimum times during the life of a wheat field for applying fertilizer, attacking weeds, or watching for pests.  One way of looking for wheat growth milestones has been found to be fairly reliable, no matter where the wheat is planted.  The key is knowing how much heat that field has experienced since the seed was planted.

Vincent Van Gogh's Wheat Fields

... in the hot Provence sun.

Growing Degree Days is the magic incantation.  Each day gets a number, which is simply the mean temperature – halfway between the high and the low – for that day.

From Hot ...
... to cold.

Just to make it a challenge, the temperatures are on the Centigrade scale and the lowest temperature that you use is never below freezing, or 0 degrees C.

Maggie's Farm -- Agoura Hills
Agoura Hills, NOAA reports, gets about 156 Growing Degree Days in December, on the average.  Since we planted Sonora, Red Fife, and Glenn at the very tail end of November, those seeds and seedlets had about 156 GDDs of magic warmth by the end of December. Maybe a bit more since the month was warm.  Another 173 during January (probably less since we had some colder weather) adds up to 329 on the 31st.  It just keeps accumulating.
What does this have to do with the entreaty, “So when is the wheat ready to eat?”

Over the years, growers have noticed how much heat is required to encourage wheat through each of its basic stages of growth.  Sprouting (or emergence), leaf development, stem growth, flowering, seed filling, and kernel maturity all require a certain number of GDDs. 

Well, maybe not a “certain” number, but an approximate guess, based on a lot of watched wheat.  And those guesses may prove a bit off if the weather is different from the average, or if we get a week of chilly downpours.   Or the goats get into the wheat.  It’s a speculation, based on estimates, opinions, averages, and hunches.

With much of our wheat now emerged from the soil up into the warm sun and well into leaf development, here’s what might happen.  Leaves will continue to appear through much of February.

Our Red Fife 54 calendar days and 279 Growing Degree Days after planting

During March we’ll see the boot stage start, with real stem growth.  That often happens after a total of 768 GDDs.  Based on previous years, Agoura Hills will reach that number on about March 26th.  

April will be time for heading, the appearance of the seed heads and maybe, before month end, the flowering of those wanna-be seeds.  During the month of May we are likely to see the kernels ripening, with maturity anytime from late in May to the middle of June. 
Or maybe earlier.             Or later.            And each of our five main varieties will be on its own schedule. 

So we’ll wait and see.  But at some point in the spring, the real timetable will make itself obvious.  Kernels will reach their full size and be considered "watery ripe."  They'll gradually turn from green to amber, and this is when the calendar is put away and it is all there in front of us, pressing kernels between our thumbnail and index finger …

... watching for the soft dough stage, the hard dough stage, the time when you can only leave a dent in the grain, and, finally, when your nail can no longer make an impression. 

Then, it’s time for harvest.

The Harvesters by Pieter Bruegel

Local grain for local mills, providing local flour for those great local loaves.    Mmmm.

1 comment:

  1. Being from KS and a poet and all that. I wrote a poem many years ago using wheat fields as a metaphor and a farmer shared a lovely little bit of data with me: when the wheat is ready, the seed heads 'relax' on the stem. The unripe wheat kernels are up, almost parallel, on the stem. When they are ripe and ready for harvest, they 'relax' and are almost perpendicular to the stem - known as 'heading out.'

    As a boy, we would start school in August and when the harvest was ready to be brought in, we would be on vacation for two weeks to help with the harvest - everyone was expected to show up in the fields because when it was ripe, it had to be brought in before any rain which might ruin it. We would start in one family's fields because they almost always ripened first (microclimate) and moved as a body from field to field harvesting the grain from everyone's fields all working together to get everything in before any rain. It was THE paramount event in my young life.

    Thank you Paul for documenting this process! I'm eager for the end of this great experiment when we can sit down and eat something!