Unflatten JSON with arrays

I have a flattened JSON that I need to Unflatten.

Flattened version looks like this below - note that "Flower" represents an array hence the "0".

{
    'Trees.ID1.Bud.Growth Season': '',
    'Trees.ID1.Bud.Axil': '',
    'Trees.ID1.Bud.Flower.0.Sex': '',
    'Trees.ID1.Bud.Flower.0.Petal Count ': '', 
    'Trees.ID1.Bud.Flower.0.Petal Colour': ''
}

I've managed to Unflatten, but unfortunately my approach treats the array as a structure.

{
    'Trees': {
        'ID1': {
            'Bud': {
                'Growth Season': '', 
                'Axil': '', 
                'Flower': {
                    '0': {
                        'Sex': '', 
                        'Petal Count ': '', 
                        'Petal Colour': ''
}}}}}}

What I'm trying to work out now is whether I need to adjust my flattened format, or the process I use to UNflatten ?

The Unflatten process I took from this post Python best way to unflat json?

from functools import reduce

def get_nested_default(d, path):
    return reduce(lambda d, k: d.setdefault(k, {}), path, d)

def set_nested(d, path, value):
    get_nested_default(d, path[:-1])[path[-1]] = value

def unflatten(d, separator='__'):
    output = {}
    for k, v in d.items():
        path = k.split(separator)
        set_nested(output, path, v)
    return output

Would appreciate any pointers as to best flatten/UNflatten in order to preserve the arrays.

You could use flatten_json:

import json

from flatten_json import flatten, unflatten_list

nested_json = {
    'Trees': {
        'ID1': {
            'Bud': {
                'Growth Season': '',
                'Axil': '',
                'Flower': [{
                    'Sex': '',
                    'Petal Count ': '',
                    'Petal Colour': ''
                }]
            }
        }
    }
}
print('Original Nested JSON:')
print(json.dumps(nested_json, indent=4))
flattened = flatten(nested_json, '.')
print('Flattened JSON:')
print(json.dumps(flattened, indent=4))
unflattened = unflatten_list(flattened, '.')
print('Unflattened JSON:')
print(json.dumps(unflattened, indent=4))

Output:

Original Nested JSON:
{
    "Trees": {
        "ID1": {
            "Bud": {
                "Growth Season": "",
                "Axil": "",
                "Flower": [
                    {
                        "Sex": "",
                        "Petal Count ": "",
                        "Petal Colour": ""
                    }
                ]
            }
        }
    }
}
Flattened JSON:
{
    "Trees.ID1.Bud.Growth Season": "",
    "Trees.ID1.Bud.Axil": "",
    "Trees.ID1.Bud.Flower.0.Sex": "",
    "Trees.ID1.Bud.Flower.0.Petal Count ": "",
    "Trees.ID1.Bud.Flower.0.Petal Colour": ""
}
Unflattened JSON:
{
    "Trees": {
        "ID1": {
            "Bud": {
                "Axil": "",
                "Flower": [
                    {
                        "Petal Colour": "",
                        "Petal Count ": "",
                        "Sex": ""
                    }
                ],
                "Growth Season": ""
            }
        }
    }
}