Wheat Growth Stages
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Week 1 Growth Stage. The plants this week are at approximately the 1 leaf stage. Seeding depth was approximately 1 inch deep. Wheat normally has 4-5 seminal (seed) roots and barley may have up to 7 seminal roots. The number that develops is dependent on variety, seed vigor and soil conditions.Growing degree days: from planting (3/29) to emergence (4/16) = 155. Growing degree days: from emergence (4/16) to 1 leaf stage (4/20) = 89.5. Accumulated growing degree days (planting to 1 leaf stage) = 244.5. Zadoks scale: 11, Feekes scale: 1, Haun scale: 1.1
Week 2 Growth Stage. Plants are at roughly the two leaf stage. They are not finished developing their second leaf. Growing degree days for week of 4/19 - 4/25 = 130.5. Accumulated growing degree days (emergence to 2 leaf stage) = 177. Zadoks scale: 12, Feekes scale: 1, Haun scale: 1.8. Pictures taken April 26.
Week 3 Growth Stage. This week the plants are at the two and three leaf stage. They are still developing their 3rd leaf. The alternate leaf pattern is becoming more visible for both wheat and barley plants. Leaves form alternately on cereals with odd numbered leaves arising from one side of the stem and even numbered leaves arising from the opposite side of the stem. When counting leaves on cereals, the first formed leaf is numbered 1, the second leaf is numbered 2, and so on. Tillers are counted in the same manner. Tiller 1 arises from the base of leaf 1, tiller 2 arises from the base of tiller 2, etc. Growing degree days for week of 4/26 - 5/2 = 110. Accumulated growing degree days (emergence to 5/2) = 277.5. Zadoks scale: 13, Feekes scale: 1, Haun scale: 2.5. Growers should begin scouting fields for wild oats at this time. Wild oats develop in a similar manner as wheat and barley. Speed of leaf development is also similar. Because wild oat susceptibility to post-emergence herbicides is influenced by development stage, it is important to properly identify the stages. One can also use the GDD information to estimate how long it will take wheat, barley or wild oat to reach specific stages. Many wild oat herbicides use seedling growth stages in label recommendations. Pictures taken May 3.
Week 4 Growth Stage. Whitebird has three fully developed leaves and one tiller. Merit barley is about a full leaf ahead of Whitebird wheat this week. This indicates that Whitebird requires more GDD for each leaf to develop than does Merit. The number of tillers that develop is dependent upon both genetic and environmental factors. Some varieties are more free tillering than others. Barley is generally more free tillering than wheat. Stresses resulting from inclement weather, too little or too much water in the soil, soil compaction, deep seeding, or nutrients out of balance may all cause decreased numbers of tillers to develop. Very high seeding rates will also reduce the number of tillers/plant due to competition between plants. Growing degree days for week of 5/3 - 5/9 = 83 Accumulated growing degree days (emergence to 5/9) = 360.5 Zadoks scale: 21, Feekes scale: 2, Haun scale: 3.4. Most important this week are things that are happening in the plants but are not yet visible. At this stage of growth, the head in the main stem has started to develop and can be seen under magnification. This is the stage when maximum number of kernels/head is determined. The maximum number of kernels for the main stem head will likely be finalized during the next two weeks. Head development for tillers follows the same sequence as for the main stem, but is delayed in timing just as tiller leaf appearance is. Any stress during this stage will result in reduced yield potential. When temperatures are high through the tillering stage, yield potential is reduced. Moderate temperatures and shorter days (longer nights) will enhance development of more kernel buds on the head (florets) and gives potential for more kernels/head. At this point, the developing head is still below ground level. It will not start to rise in the plant until tillering is completed and jointing starts. Also developing at this time but not yet visible in the pictures are the buds for adventitious roots. These roots develop from the crown nodes of the main stem and tillers, not from the seed as the seminal roots have. As adventitious roots develop, the plant will gradually become more dependent on them until they become the predominant root mass. Stress in the seedbed will inhibit development and growth of these important roots. Pictures taken May 10 at early tillering (3 main stem leaves and 1 tiller).
Week 5 Growth Stage. The wheat is fully one leaf behind the barley. (Phyllochron is the term used to describe the interval between appearance of successive leaves.) Growing degree days for week of 5/10 - 5/16 = 74. Accumulated growing degree days (emergence to 5/16) = 434.5. Zadoks scale: 21, Feekes scale: 2, Haun scale: 3.3. This plant has a developed T0 tiller, tiller 1 and tiller 2. The main stem has four fully developed leaves and the fifth leaf is about 0.3 as long as leaf 4. The heads in the wheat plant are also developing and are slightly behind that of the barley. The adventitious roots are developing and are just visible in the photograph. Neither wheat nor barley has started to joint at this time. They soon will be starting a very rapid growth stage and will need unlimited supplies of water and nutrients to maintain the yield potential that is currently being set. Producers should do everything possible to minimize any stresses during this period. For comparison, a developing head from winter wheat is shown adjacent to a dime (shown below). The winter wheat had four detectable nodes at this stage. Developing winter wheat head at jointing stage (four detectable nodes). Pictures taken May 17 at tillering (four main stem leaves and two tillers).
Week 6 Growth Stage. Growing degree days for week of 5/17 - 5/23 = 160.5 Accumulated growing degree days (emergence to 5/23) = 595 Zadoks scale: 23, Feekes scale: 2, Haun scale: 5.7. Whitebird has not yet reached the jointing stage but when examined closely, the first joint was evident but still below the soil level. (Jointing officially starts when the first joint is detectable above the soil level.) This plant has a mainstem tiller, three primary tillers plus the T0 tiller. Secondary tillers are not yet developing. The developing heads are not yet visible to the unaided eye. From a physiological stage, the wheat is similar to where the barley was last week. Any moisture, nutrient or other stress will reduce tiller number and/or head size giving a reduced yield. The plants are starting into a very rapid phase of growth (dry matter accumulation). The cooler than normal temperatures that southern Idaho experienced during the period from seeding to present have favored development of additional tillers and larger heads. Warmer temperatures through this period will result in fewer tillers and smaller heads. Recent changes to warmer temperatures will put stress on irrigation systems and the plants will change from one stage to another very rapidly. Picture taken May 24 at tillering.
Week 7 Growth Stage. Early in jointing stage. The plants this week are in a period of rapid growth and dry matter accumulation. The flag leaf will be the last leaf to emerge. Any moisture, nutrient or other stress during this period will reduce yields by forcing the plants to abort tillers or by leaving the lower florets on the heads undeveloped. Growing degree days for week of 5/24 - 5/31 = 236.5. Accumulated growing degree days (emergence to 5/31) = 831.5. Zadoks scale: 31, Feekes scale: 6, Haun scale: 7.3. The developing head in the main stem is just above ground level but barely visible at this time (approx. 1/8 to 3/16" in size). Pictures taken June 1.
Week 8 Growth Stage. Late jointing stage. Wheat will soon develop flag leaves. Plants at this stage are quite susceptible to freeze damage. Less severe temperatures can cause damage when the heads are elevated in the plant. Freezes at this stage often cause entire kernels to be aborted. Freezes after flowering may cause kernels to abort but may also cause shriveled kernels. Head emergence through flowering is the most sensitive time for freeze damage. Read "Spring Freeze Injury to Idaho Cereals" (Bulletin No. 724) for more about freeze damage. Growing degree days for week of 6/1 - 6/6 = 133.5. Accumulated growing degree days (emergence to 6/6) = 965. Zadoks scale: 34, Feekes scale: 7, Haun scale: 7.9. Developing head from Whitebird, soft white spring wheat, at late jointing stage. This head (from the main stem) was approximately 4-6 inches above ground. Pictures taken June 7 at late jointing.
Week 9 Growth Stage. Mid boot stage. The plants this week are in the middle of the fastest phase of dry matter accumulation. They are approaching the stage of maximum water use. On a hot and windy day, the plants will use as much as 0.4 inches of water a day and on a hot calm day they'll use as much as 0.3 inches of water per day. Growing degree days for week of 6/7 - 6/13 = 149.5. Accumulated growing degree days (emergence to 6/13) = 1114.5. Zadoks scale: 41, Feekes scale: 10, Haun scale: 8.5. A producer could still use Tilt and/or Cerone at this stage. Developing head from Whitebird, soft white spring wheat, at mid boot stage. The tip of the awns on this head were approximately 2-3 inches from the flag leaf collar. Pictures taken June 14.
Week 10 Growth Stage. Head emergence. This is when the plants are most susceptible to freeze damage because the heads are partially or fully exposed. Any stress during this time period will affect cell replication within the developing kernels thus reducing overall kernel size. Proper timing of irrigation is crucial during this time. Growing degree days for week of 6/14 - 6/20 = 249. Accumulated growing degree days (emergence to 6/20) = 1363.5. Zadoks scale: 53, Feekes scale: 10.2, Haun scale: 10.4. This head is approximately 4" long (excluding awns) and approximately 1/4 of the head was emerged from the boot. Pictures taken June 21.
Week 11 Growth Stage. Flowering stage. Growing degree days for week of 6/21 - 6/27 = 213.5 . Accumulated growing degree days (emergence to 6/27) = 1577. Zadoks scale: 65, Feekes scale: 10.5.2, Haun scale: 11.5. This head is approximately 5.5" long (excluding awns). Pictures taken June 28.
Week 12 Growth Stage. End of flowering. The next stage will be the soft dough stage of kernel development. Generally, soft dough stage is the time for the last irrigation. This is true for producers with a silt loam soil where the soil profile is full of water. Producers with sandy soil can irrigate beyond the soft dough stage to make up for water loss in the soil. Producers need to remember that excess irrigation will affect test weight and percent plump, increase the chance of lodging and increase the risk of disease problems associated with lodging. Excess irrigation in wheat will lower grain protein. Growing degree days for week of 6/28 - 7/5 = 210. Accumulated growing degree days (emergence to 7/5) = 1787. Zadoks scale: 69, Feekes scale: 10.5.2, Haun scale: 11.6. This head is approximately 5.5" long (excluding awns). Pictures taken July 7.
Week 13 Growth Stage. Early milk stage of kernel development. Growing degree days for week of 7/6 - 7/11 = 192.5. Accumulated growing degree days (emergence to 7/11) = 1979.5. Zadoks scale: 73, Feekes scale: 10.5.4, Haun scale: 13.0. This head is approximately 5.5" long (excluding awns). Developing kernel at early milk stage from main stem head (340 Growing degree days from heading). Pictures taken July 12.
Week 14 Growth Stage. Soft dough stage of kernel development. Growing degree days for week of 7/12 - 7/18 = 244.5. Accumulated growing degree days (emergence to 7/18) = 2227. Zadoks scale: 85, Feekes scale: 11.2, Haun scale: 14.0. This head is approximately 5.5" long (excluding awns). barley Developing kernel at soft dough stage from main stem head (584.5 Growing degree days from heading). Pictures taken July 19.
Week 15 Growth Stage. Early hard dough stage of kernel development. Growing degree days for week of 7/19 - 7/25 = 247. Accumulated growing degree days (emergence to 7/25) = 2474. Zadoks scale: 87, Feekes scale: 11.2, Haun scale: 15.0. wheat This head is approximately 5.5" long (excluding awns). Developing kernel at early hard dough stage from main stem head (831.5 Growing degree days from heading). Pictures taken July 27.
Week 16 Growth Stage. Hard dough stage. Growing degree days for week of 7/26 - 8/1 = 256. Accumulated growing degree days (emergence to 8/1) = 2730. Zadoks scale: 87, Feekes scale: 11.2, Haun scale: 15.0. Developing kernel at hard dough stage from main stem head (1087.5 Growing degree days from heading). Pictures taken Aug. 8.
Week 17 Growth Stage. Kernel hard stage of ripening. Growing degree days for week of 8/2 - 8/8 = 264. Accumulated growing degree days (emergence to 8/8) = 2994. Zadoks scale: 91, Feekes scale: 11.3, Haun scale: 16.0. wheat Kernel at kernel hard stage from main stem head (1351.5 Growing degree days from heading). Pictures taken Aug. 9.