ACQUISITIONS AND INVESTMENTS - Rhizoflora (Details) - USD ($) $ in Millions	Aug. 13, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Business Acquisition [Line Items]
Goodwill		$ 243.9	$ 254.0	$ 605.2
Minimum
Business Acquisition [Line Items]
Intangible assets amortization period		3 years
Maximum
Business Acquisition [Line Items]
Intangible assets amortization period		25 years
Hawthorne
Business Acquisition [Line Items]
Goodwill		$ 0.0	$ 0.0	$ 350.2
Hawthorne | Rhizoflora, Inc.
Business Acquisition [Line Items]
Total consideration transferred	$ 33.7
Inventory acquired	0.6
Finite-lived intangible assets acquired	10.9
Goodwill	$ 22.2
Hawthorne | Rhizoflora, Inc. | Minimum
Business Acquisition [Line Items]
Intangible assets amortization period	5 years
Hawthorne | Rhizoflora, Inc. | Maximum
Business Acquisition [Line Items]
Intangible assets amortization period	25 years