Photos, please?

what size pot was it in before you placed it in 15 gallon pot? That sounds way to big for a small 4' tree.

What type of soil was used? Did you actually repot? As in, remove all of the original soil from around the roots and place in fresh soil? Or did you pot up? Meaning you'd remove the roots with old soil intact and only fill the sides and bottom with fresh soil.

How often do you water? How much do you water? Does the pot have drainage holes?

Putting it in the dark will not help it nor will misting the leaves.

Is it an actual edible fig? Ficus benjamina, alii, lyrata?

My bet is it was either over watered or, if you did actually repot and not pot up, the roots may have been exposed for too long.

but again, I'm gonna say over watered. Probably used a heavy peat based soil which doesn't drain well on top of being in a pot far too large for the roots, meaning they never get a chance to breath, end up rotting and the tree acts as if it's staved of water.

It's not clear from your description, but I'm guessing that you purchased your fig online since Willis is a mail order only nursery. Is that correct? Had it already leafed out when you received it, or did it leaf out after it arrived but before you repotted it? If it shipped in a small tree pot (6" or so) and the potting media was still damp, then not soaking prior to planting shouldn't have been a problem. If bare root (unlikely for a fig) or if the potting mix had dried out, though, then soaking would have been beneficial.

@dave thank you for the detailed response. I ordered online and it wasn't in a pot before. It just came with the roots and a bit of soil. I got a 15 gallon (it is 16"x16") because that is what Willis Orchard suggested. It is an edible fig, Italian Bearing Fig

I used a mixture of: Miracle Gro Cactus, Palm, & Citrus Potting, Pine Fine mulch, and Espoma Organic Potting Mix. Based on your terminology it looks like I actually potted up, although, it didn't come with much soil when shipped so it's primarily my mixture.

@ernie yes, that is correct. And yes, it had already leafed out when I received it, which was only yesterday... As soon as I got the tree I went and bought soil and by the time I got back the tree was already like the picture above.

I've bought figs from a variety of mail order/internet nurseries (Burnt Ridge, Edible Landscaping, and others), and I've never received a plant that wasn't dormant on arrival (or just showing signs of waking up). Greening buds is fine, but it shouldn't be leafed out like that in my experience. You mentioned that it wasn't potted, but was the root ball in potting soil or was it bare root? How were the roots packaged/wrapped?

@ernie the rot ball only had a little bit of soil with it as well as crystal soil gel

To my mind, shipping a 4' leafed out fig tree nearly bare root (which is what it sounds like you're describing) is pretty lousy. While soaking might have helped, I really don't think you're at fault here, and, if the tree doesn't survive, I think you have good grounds to demand a refund or replacement. Nonetheless, figs are pretty resilient, so it's likely that it will bounce back. In the meantime, though, it's possible that it will drop most if not all of the existing leaves. While it attempts to recuperate, keeping it in partial shade is probably a good idea. Be sure to keep the soil evenly moist (but not waterlogged), and definitely don't fertilize it.

If you decide to buy more trees in the future, I'd steer clear of Willis. From what I've read, they have a spotty reputation, and there are a lot of good alternatives. Also, figs grow very fast when provided with the right conditions, so there's no need to pay for large trees in my opinion. In fact, smaller trees with a better shoot to root ratio will probably grow faster than a big tree that's poorly balanced.

I would defoliate the tree completely by cutting through the petioles halfway between the leaf and its attachment point and get it in an appropriate soil (DAMP is the operative word - never wet or soggy) in an appropriate size pot, in the shade, then wait for it to start pushing new growth, which it almost undoubtedly will if you can avoid rotting the roots off the plant. As soon as it's pushing new growth, start moving it into full sun gradually. If you're interested in pursuing this plan, ask any questions you might have or why certain suggestions were made.

More about trees in pots for the long term here.

Al