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Plant Analysis Sampling Instructions

Filed Under:
Publication Number: P1224
View as PDF: P1224.pdf

This publication tells you how to collect a plant tissue sample for analysis. Remember: Plant analyses and evaluations are worthless unless you submit the proper plant part. Following are instructions as to the plant part, stage of growth to sample, and the number of plants to sample.

  1. Do not sample:
    1. Dead or diseased plants.
    2. Insect- or mechanically-injured plants.
    3. Stressed plants (those that have suffered from extreme temperatures or moisture).
    4. Plants with soil-covered leaves.
    5. Plants in the advanced fruiting stages.
    6. Plants that have had no rainfall since a foliar application of insecticides, fungicides, or nutrient elements.
    7. Plants that have shown deficiency symptoms for a prolonged period of time.
    8. Early in the morning or on extremely cloudy days. Nitrates accumulate under these conditions.
  2. Place plant tissue samples inside a large paper bag. Do not wrap or enclose tissue samples in polyethylene bags (freezer bags) or other impermeable containers. Let succulent or wet tissue samples air-dry for at least one day before mailing to the lab.
  3. You may want to compare a normal plant with a suspected nutrient-deficient plant. If so, take two samples—one from the normal plant and the other from the abnormal plant. Place each sample in a separate paper bag. Use individual mailing containers, and make reference to each sample.
  4. When sampling instructions are not given for the crop you want to sample, a good rule of thumb is to sample the most recently matured leaves. If you are in doubt, contact your county Extension agent.
  5. Complete the questionnaire as accurately as possible. Feel free to write additional comments about the crop in question on a note and attach to the questionnaire. Place this information inside the small envelope attached to the mailing kit.
  6. When possible, collect a soil sample from the same location and time as the plant sample was taken. Send soil samples separately from plant samples, but make reference to each sample provided.

For more information, contact your county MSU Extension office.

Table 1. Field Crops

Stage of Growth

Plant Part to Sample

No. of Plants to Sample

Corn¹

Seedling stage (less than 12”)

All the aboveground portion.

15–20

Before tasseling

The entire leaf fully developed below the whorl.

10–15

From tasseling and shooting to silking

The entire leaf at the ear node (or immediately above or below it).

10–15

Soybeans or Other Beans²

Seedling stage (less than 12”)

All the aboveground portion.

20–30

Before or during initial flowering

Two or three fully developed leaves at the top of the plant.

20–30

Small Grain (Wheat, Oats, Rye)³

Seedling stage (less than 12”)

All the aboveground portion.

20–30

Before heading

The four uppermost leaves.

40–50

Hay, Pasture, or Forage Grasses

Before seed head emergence or at the optimum stage for best quality forage

The four uppermost leaf blades.

40–50

Alfalfa

Before or at 1/10 bloom stage

Mature leaf blades taken about 1/3 of the way down the plant.

40–50

Clover and Other Legumes

Before bloom

Mature leaf blades taken about 1/3 of the way down from the top of the plant.

40–50

Sorghum-Milo

Before or at heading

Second leaf from top of plant.

40–50

Peanuts

Before or at bloom stage

Mature leaves from either the main stem or cotyledon lateral branch.

20–30

Cotton

Before or at first bloom or when first squares appear

Youngest fully mature leaves on main stem.

20–30

¹Sampling after silking is not recommended.
²Sampling after pods begin to set is not recommended.
³Sampling after heading is not recommended.

Table 2. Vegetable Crops

Stage of Growth

Plant Part to Sample

No. of Plants to Sample

Potatoes

Before or during early bloom

Third to sixth leaf from growing tip.

20–30

Head Crops (such as Cabbage)

Before heading

First mature leaves from center of whorl.

20–30

Tomatoes (Field)

Before or during early bloom stage

Third or fourth leaf from growing tip.

20–30

Tomatoes (Greenhouse)

Before or during fruit

Young plants: leaves adjacent to second and third clusters.

Older plants: leaves from fourth to sixth clusters.

20–30

Peppers

Before bloom

Most recently matured leaf.

20–30

Beans

Seedling stage

(less than 12”)

All the aboveground portion.

20–30

Before or during initial flowering

Two or three fully developed leaves at the top of the plant (trifoliates).

20–30

Root Crops (such as Carrots, Onions, Beets)

Before root or bulb enlargement

Center mature leaves.

20–30

Celery

Midgrowth (12–15” tall)

Petiole of youngest mature leaf.

20–30

Leaf Crops (such as Lettuce, Spinach, Turnips, Mustard)

Midgrowth

Youngest mature leaf.

20–30

Peas

Before or during initial flowering

Leaves from the third node down from the top of the plant.

20–30

Sweet Corn

Before tasseling

The entire fully mature leaf below the whorl.

20–30

At tasseling

The entire leaf at the ear node.

20–30

Melons (such as Watermelons, Cucumbers, Muskmelons)

Early stages of growth before fruit set

Mature leaves near the base portion of plant on main stem.

20–30

Table 3. Fruits and Nuts

Stage of Growth

Plant Part to Sample

No. of Plants to Sample

Apples, Apricots, Plums, Prunes, Peaches, Pears, Cherries

Midseason

Leaves near base of current year’s growth or from spurs.

20–30

Strawberries

Midseason

Youngest full expanded mature leaves.

20–30

Pecans

6 to 8 weeks after bloom

Leaves from terminal shoots, taking the pairs from the middle of the leaf.

20–30

Walnuts

6 to 8 weeks after bloom

Mature leaflet pairs from mature shoots.

20–30

Grapes

From end of bloom period through August

Petioles and leaves from leaves adjacent to fruit clusters.

20–30

Berries

Midseason

Youngest mature leaves on laterals or “primo” canes.

20–30

Table 4. Ornamentals and Flowers

Stage of Growth

Plant Part to Sample

No. of Plants to Sample

Ornamental Trees

Current year’s growth

Fully developed leaves.

20–30

Ornamental Shrubs

Current year’s growth

Fully developed leaves.

20–30

Turf

During normal growing season

Leaf blades. Clip by hand to avoid contamination with soil or other material.

1/2 pint of material

Roses

During flower production

5-leaflet leaves below bud.

20–30

Chrysanthemums

Before or at flowering

Most recently matured leaf from top of plant.

20–30

Carnations

Unpinched plants

Fourth or fifth leaf pairs from base of plant.

20–30

Pinched plants

Fifth and sixth leaf pairs from top of primary laterals.

20–30

Poinsettias

Before flowering

Most recently matured, fully expanded leaves.

20–30

Begonias (Rieger elatior)

Before heavy flower formation

First leaf from top that is 2 or more inches wide.

20–30

Azaleas, Camellias

Before flowering

Most recently matured leaves.

20–30

Be sure to take the proper plant sample:

Top 2 or 3 fully developed leaves at the top of some plants (trifoliates) Mature leaflet pairs from mature shoots Ear leaf Petioles and leaves from leaves adjacent to fruit Top 6 inches of forage Soil sample from root area Above-ground portion of seedlings (less than 12 inches)


Publication 1224 (POD-12-22)

Reviewed by Keri Jones, PhD, Laboratory Coordinator, Plant and Soil Sciences.

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Authors

Portrait of Dr. Keri Denley Jones
Laboratory Coordinator
Soil Testing Lab

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