Nutrient Deficiencies
How to spot, diagnose, and treat problems of
nutrient deficiency in your indoor garden, in two parts.
Part I - Recognizing the Problem.
Before you assume your plant has a nutrient deficiency, make sure
the problem is not due to other causes. Examine the plant
carefully for plant pests, especially on the undersides of damaged
leaves, along the stem, and in the soil.
Even under the best conditions, not all leaves form perfectly or
remain perfectly green. Small leaves that grew on the young
seedling normally die within a month or two. Under artificial
lights, bottom leaves may be shielded from the light, or be too
far away from the light to carry on chlorosynthesis. These leaves
will gradually turn pale or yellow, and may form brown areas as
they die. However, healthy large leaves should remain green at
least three to four feet below the plant tops, even on those
plants under small light systems. Under low light, the
lower-growing shoots as well as the large leaves on the main stem
are affected. Some symptoms of nutrient deficiencies begin first
at the bottom of the plant, but these symptoms generally affect
the lower leaves on the main stem first, and then progress to the
leaves on the branches.
Although some deficiency symptoms start on the lower older leaves,
others start at the growing shoots or at the top of the plants.
This difference depends on whether or not the nutrient is mobile
and can move from the older leaves to the active growing shoots.
Deficiency symptoms of mobile nutrients start at the bottom of the
plant. Conversely, deficiency symptoms of immobile nutrients first
appear on the younger leaves or growing shoots at the top of the
plant. Nitrogen (N), phosphorus (P), potassium (K), magnesium
(Mg), boron (B), and molybdenum (Mb) are mobile in the plant.
Manganese (Mn) and zinc (Zn) are less mobile, and calcium (Ca),
sulfur (S), iron (Fe), and copper (Cu) are generally immobile.
Once you have determined which part of the plant is affected and
how the problem is spreading, you can isolate which 'family' of
nutrients the plant is lacking: mobile or immobile.
A dry atmosphere or wet soil may cause the blade tips to turn
brown. Brown leaf tips also may indicate a nutrient deficiency,
but in this case, more tissue will turn brown than just the end
tips.
Chlorosis and necrosis are two terms which describe symptoms of
disease in plants. Chlorosis means lacking green (chlorophyll).
Chlorotic leaves are pale green to yellow or white. Cholorotic
leaves often show some recovery after the necessary nutrient is
supplied. Necrosis means that the tissue is dead. Dead tissue can
be gold, rust, brown, or grey. It is dry and crumbles when
squeezed. Necrotic tissue cannot recover.
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