Take the following steps into consideration when collecting leaf samples:
- Avoid the outer rows of the greenhouse or field and the first and last 10 yards of a row.
- Sample leaves of average leaf quality.
- Sample abnormal plants (with deficiency symptoms) separately. If a deficiency might be present in the young or old leaves of the total crop, sample these leaves separately as a young or old leaf sample.
- Keep in mind the sunny and shady side of the plant. Always consistently sample the same side.
Time of sampling
It is strongly recommended to take the samples before 9:00 AM. The plant will then have enough leaf-tension with proper moisture conditions.
Sample the youngest, fully developed leaves and the oldest, but still vital leaves (pic. 1). From these composited leaves, only sample the middle/top leaf (pic. 2). Picture 3 shows an example of a young and an old leaf sample.
For an average, representative (young or old) sample about 20 leaves are needed. Sample size can vary, depending on leaf type (size and thickness). If you have questions about sample size, please contact us.
Packing the leaf samples
Pack the young and old leaf samples separately, these will be two different samples. Stack the leaves to assure fluent processing, (fold the leaves if needed), and put in a plastic zip-lock bag. Make sure al air is out, so any leaf evaporation is excluded (see pictures below). When leaves are wet because of rain or dew, dry them first with a tissue (see pic. 4).