Orchid failing

(Question)

I bought a beautiful orchid from a grocery about a month ago. I have been watering only once a week, I placed it in my bathroom, with indirect light, as it has a skylight near.
I noticed that inside the pot has plastoform inside and I have been watering with it. Now the plant looks sick and slowly dying. The leaves at the bottom are turning yellow and the flowers are dropping. Is there something that I could do to save it? Thanks

(Answer)

Thanks for contacting Toronto Master Gardeners. Most orchids will to drop leaves as they produce new growth. They also lose a few leaves after blooming. The blooms will fall off after a few weeks and the plant will then bloom again. The frequency of blooming depends on the type of orchid. If you have lost a lot of leaves or new leaves are falling off, there could be a problem.
Leaf loss may be related too:

Overwatering: This is a very common problem that leads to root rot which can cause leaves to turn yellow. Inspect the roots and if you some that are black or brown and mushy, remove them and reduce watering. Water the plant when the top one inch of the potting medium is dry. You mention that pot has a plastoform inside. If it doesn’t provide good drainage, it would help to repot the plant in fresh potting medium. When watering, soak the soil well and avoid watering the leaves.

Low temperatures: Ideally the room should be 15 – 20 C during the day and slightly lower at night.

Inadequate Fertilization: A potassium deficiency can cause leaves to drop. A balanced water soluble fertilizer (20-20-20 for example) at a quarter of the rate recommended for other house plants can be used to fertilize an orchid. During the winter use this solution for one of the regular waterings every 3 weeks. Feed every two weeks in the summer.
For more information about growing orchids, please see the following links:

https://www.torontomastergardeners.ca/gardeningguides/growing-orchids-a-toronto-master-gardeners-guide/

https://www.gardeningknowhow.com/ornamental/flowers/orchids/dropping-orchid-leaves.htm

https://www.gardeningknowhow.com/ornamental/flowers/orchids/common-orchid-problems.htm