Plants suffering from nutrient deficiencies can show many symptoms.  But, deficiencies in particular nutrients can show specific changes that you can identify. There are also some general symptoms that will indicate that nutrient deficiency may be affecting your houseplant. These include poor growth, failure to flower, change in coloration of leaves and browning of the leaf tips.

Some specific nutrient symptoms are:

Nitrogen (N)

The first symptom observed is that the older leaves turn pale green  and then yellow. beginning at the tips of the leaves. Eventually the whole plant will become paler in color and will not thrive.

Phosphorus (P)

Beginning with the older leaves, the plant will be dark green or assume a reddish cast. There may be necrotic (dying) spots.

Magnesium (Mg)

Leaves show yellow areas (chlorosis) between the veins, followed by necrosis (dead areas).

Potassium (K)

The oldest leaves will die, starting at their tips and proceeding along the margins of the leaves.

Calcium (Ca)

The tips of the plant stop growing. Also, the plants show a tendency to wilt.

Iron (Fe)

The leaf surfaces become yellow but the veins remain green.

Micronutrients (Mn, Mo, Zn, B, Cu, etc)

Any of the symptoms listed above can be related to micronutrient deficit, but some deficiencies result in specific effect, e. g. lack of boron or copper leads to root rot. In zinc deficiency the internodes do not elongate, so the plant becomes stunted.

Courtesy of NYBG Plant Information Plant Service