It is not very difficult for even the most unobservant gardener to tell if something is amiss with their orchid. These remarkable plants are very adept at communicating with us through their outward appearance and usually waste no time in alerting us to something they are not entirely happy with. Discoloured leaves, particularly those that are yellowish in appearance are an important warning sign that should be taken seriously.

It is not unusual for leaf shapes and appearances to vary amongst the different types of orchids. Some have squat, bulky foliage, whereas other have thinner, elongated greenery. The foliage structure is largely dependent on the environment from which the orchid originates. One thing that is universal however, is the colour of the leaves; they should appear a glossy green shade if the plant is healthy. Here we discuss potential things that may cause problems with the leaf appearance of your plant.

Temperature

Yellowing is indicative of the temperature being below the optimum values of 75-95 degrees F. Although orchids do like a drop in the overnight warmth, this still needs to be above 55 degrees. If you think this may be an issue, relocate your orchid to a warmer region; kitchens, bathrooms and shaded conservatories are excellent places to consider.

Light

Orchids love light but only if it reaches them in a diffused state as it would in nature. Many well-meaning owners forget this important fact and subject their plants to unhealthy amounts of harsh illumination which leads to scorching. Installing a net curtain or shade can easily remedy this problem, but do not expect results to be instantaneous as it may take a while for the normal green colour to return.

Over-Watering

This is another crime of over-enthusiastic and misinformed owners. This can lead to either a yellowish or a black coloration of the foliage and also cause the additional problem of root-rot. Re-potting the plant in fresh planting matter is a good solution and you may also want to consider using a pot made of a porous natural material such as clay or terracotta. Always check the dampness of the planting medium before hydrating and only add more moisture if this is almost dry to the touch.

Infections

Orchids are very susceptible to fungal infections, particularly if they have to suffer over-damp conditions. This will lead to yellowish patches on the leaves and if severe, may require dousing with anti-fungal preparations

Chemicals

Some airborne substances can be harmful to your plant. Main culprits include cigarette smoke, ammonia and chemicals from paints or detergents. Respect your orchids delicate nature and try to keep its environment as pure as possible.

Malnutrition

Most orchids need a dose of nitrogen-rich feed on a monthly basis. If your plant is not getting this it could affect its growth and ability to photosynthesise, leading to a reduced amount of chlorophyll in its leaves which will result in discolouration.

Always try to think logically when you think your orchid may be suffering from some sort of problem. Begin by ruling out the most obvious cause of the unusual leaf appearance and systematically tackle one thing at a time, letting at least a week go by before you try something new.