Make hedges in the Gazebo and use these to connect the existing hedges on the land. See map below. You need to make 82 straight and 35 corners. Square and curved corners are interchangeable, you can use either.
There is also Cactus here - chop all of these you will need them later for the Gardens of Babylon.
There is only one quest for this land.
To access Abandoned Park you need the Quadrant installed (Crafted in Architect's Manor from an Astrolabe and the Mould. The Mould is a rewarded after solving the puzzle on Architect's Manor)
Once the hedge is finished you can find underground deposits of Sulfur, Iron & Gold. find and extract these with the help of Compasses and Geologists.
Remember to take all the resources from the land including all the cactus.
Abandoned Park can be colonised.