Relentless Gardener: Decoding Nutrient Deficiencies in Houseplants

Yellow, browning, or deformed leaves on a houseplant can mean many different things.

Nutrients can be the cause of many problems in houseplants such as leaves losing color, yellowing, or turning brown. It is important to know the nutrient requirements of your houseplant.

Is it a heavy feeder? This means it needs more fertilizer than other plants required to stay healthy, and they may have a faster growth rate.

Some plants such as orchids and Ficus require high amounts of nitrogen, potassium, and phosphorus. It is recommended to use a fertilizer with a balanced ratio of nitrogen, potassium, and phosphorus but at a higher rate, or fertilize more frequently. But be careful of over-absorption of fertilizer and too much can cause root burn.

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Each type of nutrient deficiency shows up differently in houseplants. Here is a good list to follow:

A sign of nitrogen deficiency will be a general yellowing of the leaves, starting with the older inner leaves first and moving outward to the younger ones.

A sign of potassium deficiency will be when the leaf edges turn bright yellow and then scorch, but the inner leaf stays green.

A sign of phosphorus deficiency inhibits or prevents shoot growth. The leaves turn dark, dull, blue-green, and may become pale in severe deficiency.

A sign of calcium deficiency is yellowing on younger leaves first that become stunted and deformed.

A sign of iron deficiency can show up on young leaves on the top of the plant and then on the branch tips. This appears as yellowing between leaf veins with the veins remaining green.

A sign of magnesium deficiency is shown on the leaves as yellow patches between leaf veins on older veins.

A sign of sulfur deficiency starts turning the newest leaves yellow all over the plant.

Linda Langelo is a Colorado State University Extension horticulture specialist, member of Garden Communicators International, and regular contributor to MarthaStewart.com gardening articles. She also produces The Relentless Gardener Podcast. She is a guest blogger for AARP Colorado and AARP Maryland.