Sampling Procedures for Greenhouse Analysis

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.

  • Submitt 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.

Samples should be submitted with a  Diagnostic Plant Analysis Request Form (.PDF).

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

  • 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