There are at least five growth scale systems developed worldwide for wheat, the one we often use is the Feekes scale. This scale uses a numbering system 1 through 11 with each number representative of a new growth event. Each number may be further divided by using decimals to further describe a given stage. A wheat field reaches a new growth stage when more than 50% of the plants are at the next stage.
The early stages may be collectively referred to as the vegetative stages since the growing point is below the soil surface and protected from above ground environmental and pest issues. These stages would include Feekes 1 – 5. After vernalization and growth stage 5, the tissue in the growing point has differentiated to include reproductive tissue in reproductive tillers and will be pushed above the soil surface at growth stage 6. Collectively, Feekes 6 – 11 may be referred to as the reproductive stages. Currently wheat fields in Ohio are at Feekes Growth Stage 5. A description of each Feekes Growth Stage is given below:
Feekes 1.0: germination period to the first emerged leaf. The number of leaves present on the first shoot can be designated with a decimal. For example, 1.3 is a single shoot with three leaves unfolded. This stage would have occurred last October.
Feekes 2.0: tillers become visible. A tiller is a new shoot that originates underground off the main stem.
Feekes 3.0 – 4.0: tiller formation. Wheat generally will generate three to five tillers in the fall prior to the onset of winter depending on planting date. These tillers will contribute the most to grain yield. Additional tillers may develop in early spring.
Feekes 5.0: strongly erect leaf sheaths. Plants will have an upright appearance but the growing point is still below the soil surface.
Feekes 6.0: first node visible. On reproductive tillers a visible knot, bump, or swollen tissue called the node is noticeable above the soil surface. The growing point, which includes the developing head or spike on reproductive tillers is above this node. Tiller production has ceased and wheat head development will continue on reproductive tillers. See the previous newsletter for a more detailed description of this stage, https://agcrops.osu.edu/newsletter/corn-newsletter/winter-wheat-progress....
Feekes 7.0: second node becomes visible. This stage is characterized by the rapid stem elongation and further development of the head or spike.
Feekes 8.0: flag leaf visible. This growth stage begins when the last leaf (flag leaf) begins to emerge from the whorl, and the second node is visible. The flag leaf will contribute 75% of the energy needs of the developing grain.
Feekes 9.0: Flag leaf completely emerged. Complete emergence is defined when the leaf ligule is visible. The ligule is a membranous structure found at the collar or the location where the leaf blade and leaf sheath join at the stem. The flag leaf will the last leaf on the reproductive tiller. Feekes 10.0: Boot stage. The head or spike is fully developed and can be seen in the swollen section of the leaf sheath below the flag leaf.
Feekes 10.5: Heading and flowering. When the head is fully emerged the stage is further designated as Feekes growth stage 10.5. Heads generally emerge mid to late May depending on the location in the state. Flowering will generally follow within five to seven days after emergence depending on temperature. Flowering is further divided using decimals: Feekes 10.5.1 (early flowering –anthers are extruded in the center of the head), 10.5.2 (mid flowering –anthers are extruded in the center as well as top of the head), and 10.5.3 (late flowering – anthers are extruded in the center, top, and base of the head).
Feekes 11.0: Ripening. The last stage and further divided by the characteristics of the maturing grain. These subdivisions include: milk stage (11.1), mealy stage (11.2), hard kernel (11.3) and harvest ready (11.4). Temperature and daylength will determine how quickly a wheat crop moves through each stage.
A video may be found showing various growth stages at the following sites:
Feekes 7 & 8: https://www.youtube.com/watch?v=PZ7Lvsux1y8
Feekes 9 & 10: https://www.youtube.com/watch?v=OHGhq0qSM1o
Wheat heading: https://www.youtube.com/watch?v=Q6Da1HRlmV8