The stunning aesthetic of orchids is quickly marred when their stems change to any color other than a vibrant or rich green. Fortunately, I’ve dealt with this problem before, and today, I’ll talk you through the causes and solutions to the common question, “Why is my orchid stem turning white?:
Reasons Why Orchid Stems Can Turn White
After Flowering
Blooming takes up an incredible amount of the orchid’s nutrient stores, and after the phase is complete, the plant enters a dormant phase to recharge its energies. As a result, you may notice that stems change from white to brown as petals start falling off.
While it’s nothing to be alarmed about, maintaining a balance of temperature, light, and humidity during this period can guarantee the plant comes out of this cycle happy, healthy, and looking its best.
Watering Issues
Air and water are the foundations of a healthy orchid. But too much water displaces air in the soil, depriving roots of oxygen and diminishing their photosynthesizing capabilities that help create that stunning green stem.
It is recommended that orchids should be watered once a week during their dormant period and twice a week during their growth phase. Additionally, you should only use about 1/4 cup of water for full-grown plants and 1.5 tablespoons for mini orchids.
Pro Tip: If your usual watering can is too much for the plant, use a small syringe, measured spray bottle, or a piece of ice to water your orchid.
Too Much Sunlight
Dappled or indirect sunlight is what most orchid species prefer. If you notice white spots surrounded by dark circles, your orchid is getting too much light and becoming sunburnt.
The best thing to do is relocate the plant to a shadier location. If you don’t have a spot that receives indirect sunlight, you can always invest in a sheer curtain or translucent blind to filter some of the sun’s rays.
Changes in Humidity & Temperature
Nearly every orchid species does well when ambient humidity levels are between 40% to 70%. But white mold can develop and spread quickly across the stem when humidity levels exceed 70%, especially in low light conditions.
Conversely, when humidity levels drop below 40%, the plant loses its ability to absorb carbon dioxide and experiences photosynthesis issues that can cause white discoloration on the stem.
The best solution is to use humidifiers or dehumidifiers, depending on the situation. In some cases, you may be able to mist your orchid, but be aware of the water usage, as too much will also cause the whitening of the stem.
As for temperature issues, orchids fall within three preferences: cool growers, intermediate growers, and warm growers. Warm growers can tolerate as low as 64°F (night) to as high as 80°F. Cool growers fare best in the 55°F to 70°F range. Intermediate growers tend to prefer temperatures between 68°F to 75°F.
If you have trouble making it warmer or cooler for your orchid, consider using a heater, HID grow light, fan, or venting system to mimic the desired temperature.
Fertilizing Problems
Over Fertilizing
The orchid’s ability to absorb minerals and nutrients from fertilizer is limited compared to other houseplants; too much causes minerals like salt or urea to build up, creating white discoloration of the stem due to diminished oxygen intake.
I have found that a “weakly, weekly” approach is best to prevent this. Instead of a full fertilization all at once, use a diluted (1/4) fertilizer solution weekly each time you water. This way, you can avoid the threat of salt buildup, which, in addition to white stem discoloration, can also cause growth issues.
Underfertlizing
Orchids rely on fertilizer to maintain healthy growth rather than from a particular soil composition. Not giving it enough diminishes its ability to fight off pests and diseases that can lead to white discoloration. Furthermore, orchids that are not fertilized properly also have issues with moisture absorption, leading back to water management issues that cause white discoloration.
If the “weakly, weekly” method suggested above isn’t working, you can consider concentrating the dose or using a better organic orchid plant food with a 20-20-20 formula to improve its stem appearance and health.
Lack of Nutrients
Fertilization is critical to orchids getting the nutrients needed to keep stems a healthy green color. While too much or too little will lead to white discoloration of the stem, the nutrient composition in the fertilizer can also be a contributing factor.
For the best results, your 20-20-20 plant food and fertilizers should have more than the required nitrogen, phosphorus, and potassium formulation. They should also contain Humic acids and Sea Kelp extract that nourish and strengthen roots, promote a healthy immune system, and encourage more extensive plant growth year after year.
Pests & Diseases
Not all white discoloration is a result of your orchid’s growing conditions. Thrips, mealybugs, and spider mites are common pests that can cause white spots on the stem. Fungal infections such as powdery mildew and botrytis can also lead to white discoloration on the stem, especially in high humidity conditions.
Prevent these issues by using orchid-friendly leaf armor or leaf shine wipe. These solutions are the best for preventing pests and fungal diseases from affecting your orchid and can work to provide sustained protection for much longer than traditional chemical pesticides.
Stress
Anything from repotting to moving locations to changes in lighting and humidity can cause your orchid unnecessary stress, often leading to white spots on the stem. To avoid stressing your orchid, make sure to repot during growth periods, enact environmental changes gradually, and maintain consistent care habits.
Pro Tip: Invest in an orchid plant care bundle that includes everything needed to keep your plants happy and stress-free.
Orchid Care FAQ
1. Should I remove an orchid stem if it has turned white?
Orchids will continue to use energy to grow flowers, even if the stem is white. That inefficient use of plant resources can lead to stress and other growth issues. So, if you can’t correct the root cause of the white discoloration on your orchid’s stem, it’s best to remove or trim it down, especially if pests or diseases are to blame.
2. What causes white mold in my orchid potting medium?
This type of white scale results from overwatering, using mineral-rich tap water, high-humidity & low-light conditions, or poor air circulation in the soil. Depending on the severity of the mold, it may be best to repot your orchid into a new pot with a fresh, well-draining medium after isolating and removing all traces of the mold from roots to stem.
3. Why is my orchid stem turning white in the summer?
The summer heat can dry out the air and cause your orchid to use up more water than it takes in. This leads to a lack of moisture, which can cause white discoloration on the stem and other issues like wilting or drooping leaves. To prevent this, increase humidity levels around your orchid by placing a tray of water near it or misting its leaves regularly.
Solve the Mystery of White Orchid Stems
The journey of nurturing an orchid is a delicate dance where care, attention, and understanding play pivotal roles. By exploring various factors such as water management, fertilization, the presence of pests and diseases, and the stress levels of your orchid, you can accurately answer the question, “Why is my orchid stem turning white?” and enact solutions that guarantee long-term health and vitality.
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