Sampling Procedures for Greenhouse Analysis

Unless otherwise noted on our homepage, the container media and water tests are run every week. The deadline for submissions is Wednesday at noon in order the receive results by Thursday at the end of the business day. Otherwise, we will refrigerate your samples for the following week.  

For all materials, we recommend submitting your samples as soon as possible. If you're unable to ship or deliver them right away, we recommend refrigerating your samples.

Container Media Sampling

Established Plants

  • Collect a representative sample of the media by combining 5 to 10 subsamples into a single sample bag.
  • Exclude the top 1/2 inch of media, but otherwise sample from the top to the bottom of the pot.
  • Submit about 2 cups of media for Spurway analysis; for SME a quart is better.
  • Problem areas should be sampled separately.
  • For best results, follow the same procedure each time you sample so results can be compared and trends established.

New Media

  • Place the sample in a pot and water until drainage occurs.
  • When drainage stops, place the sample in a bag and submit to lab.


Irrigation and Fertilizer Water Sampling

  • Allow the water to run for 5 minutes to clear the lines.
  • Rinse a clean plastic bottle several times with the water/fertilizer to be tested.
  • Fill the bottle with approximately 1 pint (2 cups) of water and securely cap.
  • Clearly label the bottle.


Plant Samples for Greenhouses and Nurseries

Plant analysis is available for commercial customers.

Samples should be submitted with a Diagnostic Plant Analysis Request found at

For questions about sampling instructions and interpretations call the appropriate U of M Extension Specialist:

  • Submit about one full cup of plant tissue if possible.
  • Avoid dusty or contaminated samples.
  • If necessary, wash gently with demineralized water to remove contaminants; DO NOT wash dried tissue.
  • Place tissue in a loose fitting paper or cloth bag; refrigerate samples stored in plastic bags.
    • Floriculture Plants: (612) 624-9703
    • Horticultural Vegetable or Fruit: (612) 625-8114
    • Nursery Trees and Shrubs: 612) 624-7432
    • Agronomic Plants: (612) 625-6210 or (612) 625-1772

Greenhouse, Florist, and Nursery Tests