4 Reasons Why Your Orchid Stem Is Turning Yellow

Orchid stems and foliage may not be the most engaging parts of the plant, but they are usually the first parts that indicate an orchid is in distress. An orchid stem that turns yellow is experiencing chlorosis, a condition that causes plant parts to lose their healthy green color and turn yellow. In human terms, think of your orchid as turning pale. Something is amiss.

It's normal for older leaves and flower spikes to turn yellow before they dry to brown and fall off. Reddish stems on some varieties are also a natural occurrence. But when your orchid stem starts to turn yellow it's time to take corrective measures now before the underlying cause gets worse.

Yellowing stems can result from overwatering, too much sun, infection, and poor nutrition. Early steps to remedy the cause can prevent the plant from deteriorating further, turning brown or black, and eventually dying.

Overwatering

Overwatering is an underlying cause of many orchid problems including yellowing stems. It's important to keep roots well hydrated but watering too often or allowing the pot to sit in water can saturate the roots and advance excess moisture up into the stem. Water displaces oxygen causing the stem to lose healthy green tissue.

If you suspect overwatering, remove the orchid from its pot and inspect the roots. White, mushy roots indicate it's getting more water than it can absorb. Use a sterile cutting tool to remove roots that have lost all turgidity and repot the orchid with fresh, dry, potting material. Give it time to recover. Withhold water for several days and then reduce water and humidity until the stem starts to regain healthy green color. This may take several days to several weeks.

Too Much Sun

Different orchids thrive best in varying degrees of sunlight, but the type of light almost always needs to be indirect. Extended exposure to the sun hitting the plant directly can adversely affect the amount of chlorophyll in the plant, resulting in a chlorotic, yellowish stem. The heat generated by direct sunlight may also cause insufficient moisture.

Water the orchid thoroughly and allow the excess water to drain. Move the plant to a cooler location with indirect light. Withhold fertilizer until the stem regains its green color.

Nutrient Deficiency

Unless you have a greenhouse, you are probably growing an orchid as part of a houseplant collection. This often means keeping the plant in a pot with a soilless medium made up of combinations of bark, sand, moss, and perlite. Orchid potting mixes can support nutrition but provide very little actual food. This makes supplemental feeding (fertilizing) important and necessary.

Nutrition deficiencies develop when the plant gets either too much calcium or not enough nitrogen. Hard water raises calcium levels and nitrogen is the element that supports healthy green foliage. Early signs of nutrient deficiency include stunted growth, failure to bloom, and patterns of yellow or dark spots on leaves.

If your orchid has been in its same pot for more than a year, repot with fresh planting medium. If you do not fertilize on a regular schedule, start by using a 1/2 dilution of fertilizer specifically formulated for orchids. Use filtered, distilled, or tap water that has been sitting for several days to reduce the plant to excessive chemicals for watering. Fertilize monthly until you see new, healthy green growth. Fertilizing can be increased to bi-weekly once the orchid is actively growing.

Fungal and Bacterial Infection

Infections causing chlorosis in your orchid are the most difficult to correct making prevention the best treatment. Bacteria and fungi can affect any part of the orchid from roots to leaves and once the main stem starts to turn yellow, the infection has advanced beyond the early stages.

Immediately isolate the plant. Remove it from the pot and inspect the roots, removing any that appear black or mushy. Random yellowing or dark spots on leaves can also indicate infection. Severely damaged leaves can be pruned, but take care when removing them from a monopodial, single-stemmed orchid such as Phalaenopsis. Removing multiple leaves can damage the plant beyond saving. Treat all cuts with a cotton swab dipped in hydrogen peroxide.

Allow the plant to recover. If the stem on a single-stemmed orchid continues to deteriorate and turn black, the orchid should be discarded.