I was intrigued by your question, being a Westerner with no experience other than a few recipes that require filé, for which I have a jar of unadulterated powder. So thank-you for getting me to look into non-culinary aspects of sassafras. Meantime, since I wasn't reading cooks’ opinions, I picked up a different consensus than you did. The more botanical sites all said to pick the leaves while fresh and green, meaning any time before the Fall cold sets in, and roots when they're dormant mid-Winter. The exception was a site leaning more toward large applications, rather than half a dozen leaves for personal use. It said picking the leaves later into the Fall, when they were starting to yellow and turn, meant you could take more.

This made me wonder if there's that much of a culinary difference when to go foraging, or if the preferences you read about were more for the sizes of the leaves, or accessibility or the needs of the trees or any other consideration. And maybe the timing is the way grandparents did it, and that had to do with when they were going to be making a huge amount of gumbo or whatever for Fourth of July, or the annual family reunion, or the Labor Day picnic, but have to pick in the Spring to have it dried and ready for X, might only be remembered as ”sassafras has to be picked in the Spring”. You might consider contacting the sources you've been looking at to find out why they recommend what they do.

I don't have answers for you, but it's been interesting to think about. Thank-you.

A few years ago I was on a walking/hiking path in SE Mass. and I found small sassafras trees growing. I took photos to positively ID them because the leaf shape was so unusual to me. Hence, I was curious about your question now and did some research... every source that I found said that the best time to harvest sassafras leaves is just before they begin to change color in autumn.

What I neglected to consider for differentiating time to pick sassafras was growth conditions: soil composition, climate, rainfall, temperature, and so on. I don't know what happens to the flavor content of leaves during fall abscission.

As plllog stated, the need for filé is also cultural. Or based on projected use.

In any case, here's one of my experiences in making filé. Last week we had very severe wind/rain storms. A lot of sassafras twigs and leaves fell from their trees. I took advantage of the fallen leaves and proceeded to clean, dry on window screens, and trim tough veins from the leaves. Started with about 20 sq. ft. of leaves. After grinding to powder, I was left with about 2/3 cup of filé powder. For a week's effort.

When this batch runs out, I will purchase said powder.

LOL! Good idea. Maybe if you someday have a dehydrator or 5 rack air fryer it will be worth revisiting. 😃

I have a dehydrator. Window screens were easier and quieter and don't require electricity.