I need to know where to do deductions for materials in the landscape business

Use SUPPLIES  or make your own category if you wish.  

There are 17 unique categories for entering business expenses in the TurboTax Home and Business program for a Schedule C.  If you have a particular expense that does not fit in the other 16 categories listed use Other Miscellaneous Expenses at the bottom of the list.

• Click on Business
• Click on Business Income and Expenses
• Click on I'll choose what I work on
• On Profit or Loss from Business, click on the start or update button

On the next screen, click on Edit for your business listed.

On the next screen scroll down to Business Expenses          

On Other Common Business Expenses, click on the start or update button