SQL server won't run my Maintenance Plan unless I start the AQL server Agent

In SQL server management studio I have to go to SQL server agent and right click and click start, and then the maintenance plan will run, but after a reboot it won't run again until I start it again.  How can I fix this?

This is the error I get if I try and execute the maint plan when the agent is not running?

TITLE: Execute Maintenance Plan
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Execution failed. See the maintenance plan and SQL Server Agent job history logs for details.

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ADDITIONAL INFORMATION:

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)

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SQLServerAgent is not currently running so it cannot be notified of this action. (Microsoft SQL Server, Error: 22022)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=09.00.3068&EvtSrc=MSSQLServer&EvtID=22022&LinkId=20476

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BUTTONS:

OK
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