PORT ST. LUCIE — The deGrom door is open.

Last week, Sandy Alderson said there was a chance the Mets could lock up all of their young starters. Though Matt Harvey may be impossible to keep for a variety of reasons, Jacob deGrom made it clear Wednesday that he is willing to listen to a long-term contract plan.

“I’m a little bit older, so I might be more willing to do something like that,’’ deGrom told The Post at Mets pre-camp. “You just have to look at what is fair so both sides get a decent deal. It’s something I’d have to look into and make sure I agree with it.’’

There has yet to be any movement by either side on any such deal.

It would be in the Mets’ best interests to keep deGrom around as long as possible. He is not eligible to be a free agent until after the 2020 season. He will be arbitration-eligible after either 2016 or 2017, depending on his Super-2 status.

“I haven’t thought that much about it, and I have to talk to my agents and stuff and look at the numbers and decide what was favorable,’’ said deGrom, who turns 28 in June.

Looking at the numbers, the best comparison for a possible deGrom long-term contract is probably Giants ace Madison Bumgarner. Like deGrom, he had one-plus year of service time before signing long-term. He also enjoyed a promising half-season in his first year (2010) and strong success in his second year (11th place in the Cy Young voting in 2011) — deGrom won Rookie of the Year in 2014 and finished seventh in the Cy voting in 2015.

Starting in 2012, Bumgarner signed a six-year deal for $35.56 million. The contract’s max value, including 2018 vesting and 2019 team options, is $61.5 million over seven years — buying out two years of free agency, assuming the options are picked up.

If deGrom does his job, everything will take care of itself. And he knows that.

Buying out arbitration — and free agent — years has its risks and its rewards. DeGrom’s first two seasons were tremendous and he is only getting better.

In addition to the amazing arm and ability, and the even-keel approach on the mound, deGrom is one of the most competitive players on the Mets, if not the most competitive.

Don’t let his easygoing nature fool you. Underneath all that flowing hair is a warrior who wants to throttle the opposition in every way, pitching, fielding and hitting.

In fact, one of the points deGrom made Wednesday is that he is still upset with his one World Series start. DeGrom is 23-14 with a 2.61 ERA over his first two seasons. He was 14-8 last year with a 2.54 ERA and then won his first three postseason starts.

It didn’t work out against the Royals. In five innings, he gave up four runs, six hits and walked three.

The tall right-hander is determined to get back to the World Series in 2016 and get the job done.

“I wasn’t really happy with how that went,’’ deGrom said. “Hopefully I get a chance to get back there and kind of redeem myself. You never know how many starts you are going to have in the World Series, and to not have a very good one, definitely makes you want to get back and improve on that.’’

DeGrom pitched a total of 217 innings last season, counting the postseason and that one spectacular All-Star inning.

“I’m going to try to keep it the same, stay relaxed out there and just have fun,’’ he said.

The offseason has give the popular deGrom an opportunity at more endorsements. He filmed a commercial for Firestone Complete Auto Care.

“It’s fun to do that kind of stuff,’’ deGrom said. “I really enjoy it.’’

His talent and his hair make him stand out.

In his recent appearance on “Late Night With Seth Meyers,’’ Harvey mentioned the first time he saw deGrom in the clubhouse, he thought deGrom was a woman.

“Yeah, I heard about it,’’ deGrom said with a smile. “That doesn’t bother me. The hair is what it is. I get annoyed with it sometimes. But you know, I just don’t think I can cut it right now.

“I don’t want to mess with it.’’

Don’t mess with success.

DeGrom had about three inches of his hair cut off this offseason by his sister, and this weekend when he goes home, he will get it “cleaned up a little bit.’’

On Friday, the legendary Sandy Koufax may make a stop at camp to see some of the young arms like lefty Steven Matz and deGrom.

“I would enjoy sitting and talking to him,’’ said deGrom, who met Koufax at the New York BBWAA dinner after his rookie season when he won Rookie of the Year honors.

Keep learning. Keep improving. Keep winning. Big paydays are coming.