Nightshade Sproutling
Drops from Big Bag of Pet Supplies. From seed to flower, a tiny terror is grown. Elemental type. This dropped from the sproutling that attacks you when you are collecting herbs in your garrison garden.
The Nightshade Sproutling is a Warlords of Draenor profession pet that drops from the Disturbed Podling, a creature that randomly attacks you while you gather herbs in the wild or in your Garrison herb garden.
Guide awaiting review
Gather Herbs in the Wild
Head to Shadowmoon Valley or Ashran and gather herbs from wild nodes — Disturbed Podlings spawn at a notably higher rate in Ashran, somewhere between 33% and 50% per herb node, making it the most efficient zone for farming the Nightshade Sproutling.
Defeat the Disturbed Podling
When a Disturbed Podling spawns and attacks you, defeat it for a chance at the Nightshade Sproutling — the Podling scales to your character's level, so it will be a level 110 enemy if you are level 110.
Skip the Garrison Garden
As of May 2018, Disturbed Podlings no longer appear to spawn in the Garrison herb garden, so farming wild herbs in zones like Ashran or Shadowmoon Valley is the reliable method for obtaining this pet.
Tips
One player obtained the Nightshade Sproutling after approximately 94 herb-gathering attempts, tracked across wild nodes.