IMPAIRMENT, RESTRUCTURING AND OTHER - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Apr. 01, 2017	Mar. 31, 2018	Apr. 01, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, long term	$ 1.1		$ 1.1
Charge recognized for probable loss	10.2
Scotts Lawnservice
Restructuring Cost and Reserve [Line Items]
Divestiture transaction related costs		$ 0.1		$ 0.7
International Business
Restructuring Cost and Reserve [Line Items]
Divestiture transaction related costs	0.2	2.3	1.6	3.9
Project Focus | Scotts Lawnservice
Restructuring Cost and Reserve [Line Items]
Divestiture transaction related costs		0.1		0.7
Project Focus | U.S. Consumer
Restructuring Cost and Reserve [Line Items]
Restructuring charges and adjustments	(0.1)	$ 1.0	(0.3)	$ 0.8
Restructuring costs incurred to date	9.8		9.8
Project Focus | Hawthorne
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred to date	1.0		1.0
Project Focus | Other
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred to date	$ 1.2		$ 1.2