That message was directed at New Zealand First, which hardly needs reminding that dealing with National as a single large party is simpler than dealing with Labour.
That is because Labour has to square away major components of its own deal with the Greens with New Zealand First as well.
Labour could hardly agree to the Greens' policy to remove all sanctions on beneficiaries, for example, without the agreement of New Zealand First, which supports a work-for-the-dole approach to welfare.
Peters needs the Greens in any deal with Labour but refuses to meet with them - either separately or together with Labour despite James Shaw extending an olive branch to Peters on election night.
But English's main criticism of the Greens was the way it exercises its power.
It was not a last-minute bid by English to get the Greens to switch sides for a so-called "teal deal".
It was a bid by English to talk up the power that the Greens hold in the hope that the party negotiators exert more pressure in their talks with Labour.
The more Green policy that Labour has to accept, the more attractive a National deal might be for New Zealand First.
Green Party leader James Shaw has been holding talks this morning with Labour leader Jacinda Ardern at Parliament ahead of Labour's talks with New Zealand First at midday.