The event starts September 28th and goes until October 9th. There are two halves to the event.
In the first half (starting on September 28th):
types of seasonal seeds are available for planting: apple lollipoppy
seeds and peach lollipoppy seeds. Both types of seeds can be received by
animal requests. Apple lollipoppy seeds can be purchased from Lloid. Peach lollipoppy seeds can be received by sharing spooky bats and eerie bats in other people's gardens.
Two types of rare
creatures can be acquired. Spooky bats can be found on newly
bloomed apple lollipoppies. Eerie bats can be found on newly bloomed peach lollipoppies.
In the second half (starting on October 2nd):
new type of seed is available: plum lollipoppy seeds. They can be acquired
from completing requests or sharing scary bats or haunting bats in other's gardens.
Two types of bats, scary and haunting, can be found on newly bloomed plum lollipoppies.
Capture enough of each type to gain prizes ranging from essence and Leaf Tickets to clothing and furniture.
Again part of this event are "Hard Tasks". These are bonus tasks for
the event once you have completed the regular ones needed to acquire
all the items. Completing hard tasks will grant you recoloured versions
of items obtained throughout the event. Note that these items will not
appear in the catalog, and will not count towards event completion.
Additionally there are spooky terrain pieces for every section, including the fence.