Did My Winter Wheat Vernalize?

One key difference between winter and spring wheat is that winter wheat needs to vernalize to trigger the transition from vegetative to reproductive growth.  This accumulation of cold units occurs when soil and ambient temperatures are roughly between 32 and 50°F. Last fall was very dry, and despite seeding the winter wheat on time, the seed lay in dry dirt for several weeks. Several of you have asked whether this winter wheat would have vernalized to produce grain this season.  Ideally, you want to accumulate those cold units in the fall after seeding, and a seedling, even if it has not reached the soil surface yet, accumulates those cold units.  That accumulation will continue in the spring if needed

There is no way to tell if an individual plant has accumulated enough cold units to transition from vegetative to reproductive growth until jointing or stem elongation is underway. As wheat reaches the four-leaf stage, the plants will become more erect.  This is referred to as pseudo-stem elongation and does not mark the transition from vegetative to reproductive growth.  To determine if stem elongation or jointing is underway, you can pull plants up and, with two fingers pinched together, go up along the main stem, starting at the crown.  The crown will feel like a hard knot.  If you feel a second hard knot as you go along the stem upwards, the plant is jointing, and stem elongation is underway. You can also cut the main stem longitudinally and see whether there is a section of hollow stem between the crown and the developing head (Photo 1). Stem elongation is well underway in winter rye and should get underway in winter wheat at any time now.  

Photo 1 - The first internode or hollow stem between the crown and the developing grain head
in winter wheat (Photo Credit: Romulo Lollato, Kansas State University)