Short answer
Build the Lifting Crane in the Garden with 8 Wooden Beam, 3 Bronze Gear and 4 Iron Detail. Zombie Gardening unlocks it; building the crane unlocks Garden Storage II.
Home and garden
View full-size image ↗Official promotional screenshot · © Lazy Bear Games / tinyBuild · Official media kit · Material credits
Unlock and build
Research Zombie Gardening after Garden Improvement I. It costs 60 green and 20 blue tech points and also unlocks the Gardener Stand and crop tablets.
At the Garden build desk, prepare 8 Wooden Beam, 3 Bronze Gear and 4 Iron Detail for the crane.
What the crane opens
The crane is a prerequisite for Garden Storage II. If you are looking for that storage upgrade, check whether the crane has already been built in your Garden.
Keep the garden jobs separate
Zombie Gardening unlocks several objects together. The Lifting Crane opens storage progression; the Gardener Stand and crop tablets are the separate pieces to check when setting up crop automation. See the linked gardening guide for that setup.
Sources
Related pages
Official screenshot · © Lazy Bear Games / tinyBuildAutomationGraveyard Keeper 2 Zombie Gardening & Gardener StandOfficial screenshot · © Lazy Bear Games / tinyBuildAutomationGraveyard Keeper 2 Fertilizer
Official screenshot · © Lazy Bear Games / tinyBuildAutomationGraveyard Keeper 2 Factory Layout & Setup