Hi, Why My Calathea Arundinacea New Leaf Has This Spot On It? Is This Related To Fungal Disease?

Question

I water it one times a week.

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Answer 1

It is too young and small too say! This can come from a small injury while it is emerging, or an actual deficiency, or even a pH issue. To be sure, you can test for nutrient content and pH.

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm

This article will help you with the plant's care:

https://www.gardeningknowhow.com/houseplants/calathea-plants/calathea-zebra-houseplant.htm