Knowledgebase
Petunia seedlings leaves turning white #745028
Asked April 19, 2021, 9:19 AM EDT
Hi. I was wondering if you could tell me why my petunia leaves are turning white on some of the plants. They are planted in that seed starter mix that has some kind of coconut husks in it. Some weak fertilization with Peters bloom stuff. Other packs are perfectly green using the same seed. Included is a pic. Thanks for your help. Teresa
Benzie County Michigan
Expert Response
Hello,
It looks to be an iron deficiency in the plants. Sometimes the pre-mixed bags of growing media are not the most consistent and the pH can vary from what's in the bag. Make sure that you are using a fertilizer that has micronutrients and considering increasing the amount of fertilizer. You can test the pH of the growing media which should be between 5.5 and 6.2. This is a guide that has been created for professional growers:
https://e-gro.org/pdf/2018_705.pdf
Here is a guide on how to test pH of young plants grown in plug trays (like you have): https://sites.google.com/view/fertdirtandsquirt/plugs?authuser=0
For homeowners, altering the pH can be a little challenging but you can get supplies at a gardening supply company: https://hgic.clemson.edu/factsheet/changing-the-ph-of-your-soil/
Thanks!
Heidi
You are welcome!
