This datapack, which requires both Pam's Harvestcraft 2 - Crops, Pam's Harvestcraft 2 - Trees, and Botania, allows you to use Botania's Alchemy Catalyst to create the various gardens from Pam's, as well as transmute Pam's saplings into other kinds.
To start, you need to make one Floral Fertilizer from Botania, and throw it into a mana pool with an Alchemy Catalyst. This creates a Windy Garden, and from there you can transmute between the gardens as follows:
Windy -> Tropical -> Soggy -> Shaded -> Frost -> Arid -> Windy
You can start transmuting saplings as soon as you get any Pam's sapling, or if there simply are no fruit trees in the area, you can transmute an apple sapling from one of Botania's Pasture Seeds.
The transmutation cycle for saplings is too long for me to bother transcribing it here (48 recipes), but it loops just like the garden cycle does.