Q.Passion Fruit
Hello,
My passion fruit leaves became yellow?
Can you please advise .?
When is best time to give food for soil?
Thank you for your support,
Fara Pourkiani

Certified GKH Gardening Expert
The first thing that you will want to do is test your soil's pH and nutrient content before you add anything. These articles will help: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
If you determine that you, indeed, have a nitrogen deficiency then you may feed right as the vigorous growing season starts.
The best way to feed, however, is mulching each year with fresh compost. This will break down over the year and give them nutrients slowly.
This article will help you to grow passion fruit:
https://www.gardeningknowhow.com/ornamental/vines/passion-flower/passion-flower-care.htm