Michael Appleton has warned Pompey cannot afford to rely on their youngsters in League One.
No fewer than seven teenagers attended the recent 10-day Spanish training camp.
Meanwhile, other first-year professionals Alex Grant, Andy Higgins and Elliot Wheeler remained at home to train with coach Guy Whittingham and the senior players.
The massive number of players promoted from the club’s Academy this summer is not only a reflection of the youngsters’ abilities but also the necessity for the club to become more self-sufficient.
Appleton has already indicated Ashley Harris, Adam Webster and Sam Magri will be part of his first-team set-up this season.
However, he remains concerned the vast majority are not yet ready to feature for the senior side.
Pompey fans will again get the chance to see some of them in action for the visit of Bolton tomorrow (3pm).
But Appleton has called for patience over their on-going development.
He said: ‘Let’s be absolutely, completely blunt.
‘If we are going into the season with kids, there is only one thing that is going to happen, end of story.
‘No-one can blame them and expect any different but let’s just get real for one second.
‘They need massive, massive help and they need time. They are not ready for this type of football at all – as in the amount of numbers we are talking about.
‘Two or three might come through to be part of an experienced team and a team that can be successful – but certainly not seven, eight or nine of them.
‘If they are lucky enough to get a few minutes here, a few minutes there, then all of a sudden a couple of them are lucky enough to get a start, then great.
‘We must all realise, though, the kids are not going to be the answer in making sure Portsmouth have a really competitive season.’
In addition to Harris, Webster and Magri, four other youngsters have featured during pre-season friendlies so far.
Former Hampton & Richmond striker Dan Thompson netted against Brighton in the 5-1 defeat in Spain.
Others who have played include left-back Dan Butler and attacking midfielders George Colson and Jed Wallace – all Academy regulars under Andy Awford last term.
And Pompey’s boss was impressed with how the seven handled themselves during what was their maiden Pompey tour recently.
Appleton added: ‘What I was able to do on the tour was give a little bit of time to some of the young players.
‘They probably don’t get as much of my time as they would like throughout the season, especially when the games get going.
‘That has been great, not only seeing them in training but seeing them in games as well.
‘It has helped me get an understanding of what sort of things they can cope with. That has helped.
‘Two or three of them may have to play their part at some point during the season.
‘So for them to get a little bit of play like they’ve done so far in pre-season is good for everyone all round.’