It’s getting to be the end of May and you do not have your corn planted yet. What do you do? Well, the first thing not todo is panic! We still have plenty of time to plant corn and have some outstanding yields. The first question to ask yourself is why did you choose the hybrid that you did? In most cases it was because it yields well for your farm and your fields. That hasn’t changed!

Here are a few ideas to consider before you jump the gun:

  1. As planting dates become deeper into May and the 1st of June hybrids react differently than they do in April and the 1st of May.
    1. According to Purdue University and The Ohio State University, as planting is delayed, the number of necessary GDDs from planting to Silking decreases by about 106 GDDs per day of delayed planting. The number of necessary GDDs from planting to kernel black layer decreases by about 6.8 GDDs per day of delayed planting. This data indicates that we can still plant full season hybrids much later than we previously thought! For example, if a hybrid normally requires 2,800 GDDs from planting to maturity, then it will require slightly less than 2,600 GGDs if planted on May 31 rather than May first.
  1. How much do you lose by late planting corn?
    1. According to Dr. Bob Nielsen (Purdue University) and Emerson Nofziger (Illinois University) “Estimated yield loss per day with delayed planting varies from about 0.3% per day early in May to about 1% per day by the end of May. Yield potential goes down with delayed planting because of a number of factors, including a shorter growing season, greater insect & disease pressure, and higher risk of hot, dry conditions during pollination”. An example would be if you had a yield potential of 200 bushels at the end of April your expected yield at the end of May would be around 182 bushels. If your other yield factors were the same.

Ok, so when do you make the changes?
First and foremost, there is no cut and dried dates! They will vary for each of you, but here are some suggestions from your GRO-MOR Seed Specialist:

  1. Keep planting your original planned hybrids until the end of May.
  2. During the first week of June you may consider switching from a full season (110-112 day) to a mid-season (106-108 day) corn.
  3. From the 1st week of June until the early part of the second week consider switching to an early season corn (101-106) hybrid.
  4. After the second week of June then make the switch from Corn to Soybeans.

Again, these are not hard fast rules, they are suggestions. There are never any guarantees in this business. Talk to your Crop Insurance company to see how their dates will affect your decisions. If you have livestock, this too should weigh into the above factors. Talk to Jim Swartz or Katie Hartman to see how this could change your marketing options. In other words, look at the big picture and not just the calendar.

Here are some other related reading materials to help in your decision-making process.

Myers, Brent and Bill Wiebold. 2013. Planting Date 2013. Univ of Missouri Extension [On-line] [URL accessed May 2018].

Nafziger, Emerson. 2008. Thinking About Corn Planting Date and Population. The Bulletin (No. 2, Article 7, April 4), Univ. of Illinois Extension. [On-line]. http:// [URL accessed May 2018].

Nielsen, RL (Bob). 2017. Corn & Soybean Planting Progress in Indiana Over the Years. Corny News Network, Purdue Extension. [On-line]. [URL accessed May 2018].

Thomison, Peter, Steve Culman, & Mark Loux. 2015. Adjusting Corn Management Practices for a Late Start. C.O.R.N. Newsletter, Ohio State Extension. [On-line] [URL accessed May 2018].

If you have questions, please feel free to talk to your Luckey Farmers Agronomist or give your Luckey Farmers Seed Specialist a call.

Ed Thurn                                 Doug Uher                              Terry Hoover
419-680-2279                         419-346-3804                         419-343-4434