How to take a plant sample

The when and how of plant sampling is very dependent on the crop sampled. Instructions for sampling and submitting samples as specified by the lab should be followed. See specific instructions on the plant analysis sub-pages for selected fruits, vegetables and trees and field crops.

When no specific sampling instructions are given, the general rule of thumb is to sample upper, recently mature leaves. The recommended time to sample is just prior to the beginning of the reproductive stage for many plants. Here are some additional guidelines:

  • Paired samples – Where a deficiency is suspected, take samples from normal plants in an adjacent area as well as from the affected area. It is recommended to also take a soil sample from each area.
  • Sample 25 to 30 plants throughout the area
  • Dusty plants should be avoided – If dust is present, brushing or wiping with a clean damp cloth may be sufficient. If not, rinse briefly with water while the material is still fresh.
  • Care and handling of sample – Air dry the sample, put in a clean paper bag or envelope and take it to your local county extension center or mail it to the lab. For more information on where and how to send samples, visit the How to submit samples page.
  • Complete the sample information form – See the button below for a link to the form that needs to be completed and submitted along with the sample. This is essential for the lab to properly interpret the plant analysis.

Plant sample form

Plant test procedures and results

  • Plant analysis procedures (PDF)
  • We use the sufficiency and survey ranges as reported in the Plant Analysis Handbook II by Harry A. Mills and J. Benton Jones, Jr. 1996. MicroMacro Publishing, Athens, Ga.