N.Y. Comp. Codes R. & Regs. tit. 20, § 541.12 – Landscaping, nurseries and greenhouses.

(a) Landscapers and operators of nurseries and greenhouses are considered contractors when performing capital improvements or repairing, maintaining or servicing real or tangible personal property and are subject to the provisions of this Part.
Cross-reference:
For purchases, see section 526.6(b) of this Title.
(b) Tangible personal property produced for sale, but withdrawn from inventory and installed as part of a capital improvement is subject to the use tax. The computation of the tax is based on the price at which the vendor charges other installers. The tax rate used is the rate in the taxing jurisdiction where the tangible personal property is installed.
(c) A landscaper-contractor who produces tangible personal property solely for installation in the performance of his capital improvement contracts does not qualify for the farming exemption provided by section 1115(a)(6) of the Tax Law, and is therefor, subject to tax on all purchases of property, supplies and equipment. No use tax is due when the tangible personal property is so installed.