Plant tissue analysis has increased greatly in the past 5 years. Tissue nutrient analysis is a very useful tool for trouble shooting problem areas in fields when used with a soil test. Agronomist often ask our staff if there is a best time of day to collect tissue samples. We searched for research on this topic and did not find much information. To give our customers more information, we did a demonstration project last summer. This project included collecting plant samples at 9am, 11am, 1pm, 3pm and 5pm. Tissue samples were collected from corn, soybeans and wheat at various stages of growth. All samples were collected in triplicate for this demo project. The figures show a few examples of nutrient levels from tissue samples collected at different times of day from various crops. As you can see from these figures, there are no significant differences in the nutrient levels when samples are collected between 9am and 5pm. Please call if you have questions.