H-2 B visa is designed for Non-agricultural seasonal workers. Employer has to obtain labor certification from Department of Labor for its worker and subsequently apply to USCIS on behalf of workers on Form I-129. 

There is a statutory numerical limit, or “cap,” on the total number of individuals who may receive H-2B non-immigrant classification during a fiscal year. The Congress set up a numerical cap to 66,000 which are divided between the first half of the fiscal year (October 1 through March 31) and second half of the year (April 1 through September 30). 

USCIS has received a sufficient number of petitions to reach cap for  H-2B status for the first half of fiscal year  2015. 

Please do not send any H-2B petitions with request of employment start date prior to April 1, 2015.

See more info http://www.iv-law.com/immigration-lawyer/non-immigrant-visas/h-2-temporary-workers/