The European Christmas tree growers recommend GlobalG.A.P.

There are many different national certification standards within the member countries of the Christmas Tree Grower Council of Europe. These standards may be more or less targeted at different client segments and/or production methods, and they may have greater or lesser national focus.

In order to provide common certification standards, the members of the Christmas Tree Grower Council of Europe have agreed on recommending GlobalG.A.P. as the most commonly used certification standards across Europe.
GlobalG.A.P. is a private, global organisation that has developed standards for agricultural production defining requirements in respect of quality, the environment, working environment, social matters and hygiene. GlobalG.A.P. is based on the individual countries' national legislation focusing on traceability and documentation via unbiased audits.

Today, GlobalG.A.P. is used in more than 130 countries by more than 110,000 companies, and therefore certification standards are diffused as the B2B-certification standards in many of the trading channels that are trading Christmas trees. My means of the GlobalG.A.P. purchasers obtain assurance for correct production methods and handling of the products to the benefit of consumers and the environment.

Read more about GlobalG.A.P. : http://www.globalgap.org/uk_en/