Crop |
When to Sample |
Plant Part to Sample |
Number of Leaves in Sample |
Alfalfa |
Early growth up to 1/10 Bloom stage |
Entire top 15 cm of plant |
45-55 |
Apple |
Late summer just after the end of terminal growth |
Youngest fully expanded leaf from non-fruiting terminals |
75-100 |
Apricot |
Late summer just after the end of terminal growth |
Youngest fully expanded leaf from non-fruiting terminals |
75-100 |
Beans |
Seedling stage |
Entire above ground portion |
25-30 |
Beans |
Before or during initial flowering |
Youngest mature leaves from the top of the plant |
25-30 |
Beets |
Before root or bulb enlargement |
Centre mature leaves |
25-35 |
Broccoli |
Before heading |
First mature leaves from centre of whorl |
10-20 |
Cabbage |
Before heading |
First mature leaves from centre of whorl |
10-20 |
Carnations |
Pinched plants |
5th and 6th leaf pair from top of primary laterals |
20-30 |
Carnations |
Unpinched plants |
4th and 5th leaf pair from terminal of plant |
20-30 |
Carrots |
Before root or bulb enlargement |
Centre mature leaves |
25-35 |
Celery |
Early to mid-growth |
Petiole and leaf of youngest mature leaf |
20-30 |
Cereal Grains |
Prior to heading |
First 4 leaf blades from top of plant |
30-40 |
Cereal Grains |
Seedling stage (less than 30 cm) |
All the above ground portion of plant |
50-75 |
Cherry |
Late summer just after the end of terminal growth |
Youngest fully expanded leaf from non-fruiting terminals |
75-100 |
Chrysanthemums |
Before and during early flowering |
Youngest mature leaves on flowering stem |
20-30 |
Clover and Other Legumes |
Prior to bloom |
Mature leaf blades about 1/3 of the way down the plant top |
50-60 |
Coffee |
Early to mid-season |
Mature leaves of current year's growth |
40-50 |
Confer |
In spring, when it has about 2 inches of new growth |
Collect 2 inches of new tip growth (entire tip including stem). Collect from the same side of the tree at the same height on each tree. |
approx. 30 tips |
Corn |
Seedling stage (less than 30 cm tall) |
All the above ground portion |
25-30 |
Corn |
Just before tasselling |
The fully developed leaf below the whorl |
15-20 |
Corn |
Tasselling to silking |
The leaf at the ear node or the one above or below it |
15-20 |
Cotton |
Early growth, at first bloom and when first squares appear |
Youngest fully mature leaves on main stem |
30-35 |
Cucumber |
Early stage of growth prior to fruit set |
4th to 6th leaf from terminal on main stem |
20-25 |
Cucurbits (Cucumber, Melons, etc.) |
Early stage of growth prior to fruit set |
4th to 6th leaf from terminal on main stem |
20-25 |
Deciduous Fruit (Apple, Apricot, Almond, Cherry. Peach, Pear, Prune) |
Late summer just after the end of terminal growth |
Youngest fully expanded leaf from non-fruiting terminals |
75-100 |
Forage and Pasture Grasses |
Before head emergence or at the stage of best quality |
The uppermost leaf blades |
50-60 |
Grains(Small, Including Rice) |
Seedling stage(less than 30 cm) |
All the above ground portion of plant |
50-75 |
Grains(Small, Including Rice) |
Prior to heading |
First 4 leaf blades from top of plant |
30-40 |
Grapes |
During bloom period |
Leaves and petioles opposite the flower cluster |
75-100 |
Head Crops(Cabbage, etc) |
Before heading |
First mature leaves from center of whorl |
10-20 |
Leaf Crops (Lettuce, Spinach, etc.) |
Before mid-growth |
Youngest mature leaf |
30-50 |
Lettuce |
Before mid-growth |
Youngest mature leaf |
30-50 |
Lemon, Lime |
During autumn growth flush |
Mature leaves from last flush of growth on non-fruiting terminals |
30-40 |
Melons |
Early stage of growth prior to fruit set |
4th to 6th leaf from terminal on main stem |
20-25 |
Milo-Sorghum |
Before or at heading |
2nd leaf from top of plant |
20-25 |
Onions |
Before root or bulb enlargement |
Centre mature leaves |
25-35 |
Orange |
During autumn growth flush |
Spring cycle leaves, 4 to 7 months old from non-fruit-bearing terminals |
25-30 |
Ornamental Trees and Shrubs |
Current year's growth |
Fully mature leaves |
30-75 |
Peach |
Late summer just after the end of terminal growth |
Youngest fully expanded leaf from non-fruiting terminals |
75-100 |
Peanuts |
Before or at bloom stage |
Youngest fully developed leaves from top of the plant |
40-45 |
Pear |
Late summer just after the end of terminal growth |
Youngest fully expanded leaf from non-fruiting terminals |
75-100 |
Peas |
Before or during initial flowering |
Leaves from the 3rd node down from the top of the plant |
30-50 |
Pecans |
After the end of terminal growth |
Mature leaves from terminal shoots, taking the pairs from the middle of the leaf. |
30-45 |
Plum |
Late summer just after the end of terminal growth |
Youngest fully expanded leaf from non-fruiting terminals |
75-100 |
Potato |
During vegetative growth |
3rd to 6th leaf back from growing tip |
30-50 |
Pineapple |
During vegetative growth |
Young mature leaves |
10-15 |
Poinsettias |
Before and during early flowering |
Most recently mature fully expanded leaf |
15-20 |
Potato |
During vegetative growth |
3rd to 6th leaf back from growing tip |
30-50 |
Prune |
Late summer just after the end of terminal growth |
Youngest fully expanded leaf from non-fruiting terminals |
75-100 |
Radish |
Before root or bulb enlargement |
Centre mature leaves |
25-35 |
Raspberry |
From early growth through mid-season |
Youngest mature leaves on lateral or primary canes |
25-40 |
Rice |
Prior to heading |
First 4 leaf blades from top of plant |
30-40 |
Rice |
Seedling stage (less than 30 cm) |
All the above ground portion of plant |
50-75 |
Root Crops (Carrots, Beets, Onions, etc.) |
Before root or bulb enlargement |
Center mature leaves |
25-35 |
Roses |
Before and during early flowering |
Upper mature leaves on the flowering stem |
25-30 |
Small Grains (Including Rice) |
Prior to heading |
First 4 leaf blades from top of plant |
30-40 |
Small Grains (Including Rice) |
Seedling stage (less than 30 cm) |
All the above ground portion of plant |
50-75 |
Soybeans |
Or prior to or during initial flowering |
Fully developed leaves at the top of the plant |
20-30 |
Soybeans |
Seedling stage (less than 30 cm tall) |
All the above ground portion |
20-30 |
Spinach |
Before mid-growth |
Youngest mature leaf |
30-50 |
Squash |
Early stage of growth prior to fruit set |
4th to 6th leaf from terminal on main stem |
20-25 |
Strawberry |
From early vegetative growth to early fruiting state |
Youngest fully expanded mature leaves |
50-70 |
Sugar Beets |
Before mid-season |
Fully mature leaves midway between the younger center leaves and the oldest leaf whorl on the outside. |
30-35 |
Sugar Cane |
Up to 4 months old |
4th fully developed leaf from the top of the plant. |
25-30 |
Sweet Corn |
Before tasselling |
The entire fully mature leaf below the whorl |
20-35 |
Tobacco |
Before bloom |
Uppermost fully developed leaf |
8-12 |
Tomato (Field) |
Before early bloom stage |
3rd to 4th leaf back from growing tip |
20-35 |
Tomato (Greenhouse) |
Before bloom |
Young plants: Leaves from 2nd and 3rd clusters |
20-35 |
Tomato (Greenhouse) |
Before bloom |
Older plants: Leaves from 4th to 6th clusters |
20-35 |
Turf |
Anytime during growing season |
Leaf blades, avoid soil contamination |
500 cc of material |
Walnut |
After the end of terminal growth |
Middle leaflet pairs from mature shoots |
30-40 |