Foliar mineral analysis helps distinguish between deficiency disorders and other issues such as
disease (this lettuce is showing advanced potassium deficiency).
Water analysis reports that show a high
pH and moderate to high alkalinity
(which is the strength of a high pH) give
growers valuable information on how
pH may need to be adjusted. Highly
alkaline waters are best treated with
acid before they are introduced to the
hydroponic system, which provides a
greater buffering capacity and less acid
will be required overall to keep pH
levels down over time.
Foliar Analysis
Foliar analysis is another useful tool for
growers that can provide insightful and
valuable information on the nutritional
status of a hydroponic crop. Foliar
analysis samples need to be collected
correctly to be accurate; this involves
taking leaves at the correct stage of
growth, often the youngest mature leaf,
combined from several different plants to
ensure a representative sample is being
tested. These are then sent directly to
the lab before the leaves can deteriorate.
Foliar analysis is used for a couple of
different reasons. First, it can routinely
monitor nutrients in the plant tissue to
help sustain growth and avoid nutritional
disorders in the crop that impact yield.
Second, it can be used as a diagnostic
tool to identify nutrient deficiencies,
toxicities, or imbalances when plants
appear to be underperforming or
showing strange symptoms.
While foliar analysis gives an insight
into the current nutritional status of a
plant or crop, it doesn’t reflect what the
plant is taking up at the time of testing.
Foliar mineral levels are representative
40
Maximum Yield
LETTUCE
Foliar analysis of healthy plants can help
determine the required nutrient levels and
ratios when growing a new crop where little
nutrient formulation information is available.
TOMATO
ROSE
STRAWBERRY
N % 3.1-4.5 4.5-5.5 3.0-5.0 2.6-3.5
P % 0.35-0.60 0.40-0.70 0.25-0.50 0.25-0.35
K % 4.5-8.0 4.0-6.0 1.5-3.0 1.0-2.0
Ca % 0.80-2.0 1.20-2.0 1.0-2.0 0.70-1.50
Mg % 0.30-0.70 0.40-0.70 0.25-0.50 0.25-0.40
S % 0.20-0.30 0.60-2.0 0.25-0.70 0.15-0.35
0 – 0.30 0.08-0.15 0.0-0.10 0.02-0.10
Fe (ppm) 50-100 80-200 60-200 100-200
Mn (ppm) 50-300 50-250 30-200 200-500
25-55 30-60 30-60 30-100
Zn (ppm) 25-250 30-60 17-100 30-80
Cu (ppm) 7-80 15-50 7-25 5-12
Na %
B (ppm)
TABLE 1: Typical foliar mineral levels by hydroponic crop.
“
REGULAR FOLIAR ANALYSIS does provide long-term
information on how minerals levels change through
the crop life cycle and when nutrient formulation
adjustments should be made.”
of the nutrients being taken up at the
time tissue was forming, and for some
slow-growing species that may have
been several weeks previously. Regular
foliar analysis does provide long-term
information on how minerals levels change
through the crop life cycle and when
nutrient formulation adjustments should
be made, particularly when plants move
into the flowering and fruiting phases.