Adam May has been told he can have a Pompey future.
But the midfielder has been warned he has to seize his loan opportunity at League Two Swindon.
The 21-year-old is entering the final year of his existing deal at Fratton Park after making 30 senior appearances.
Jackett promised he has a chance to stay at the club he emerged at - but has to now prove his worth with the Robins.
He said: ‘I’ve let Adam May go to Swindon for the season.
‘Paul Jewell (Swindon’s director of football) phoned me.
‘He can 100 per cent have a future here. A lot will depend on what he does there, but the chance is there for him.
‘For me, I did think it was too good an opportunity for Adam to turn down.
‘If it was a National League side or something like that it may have been different, but Swindon is a good club.
‘Him going there is a really good one, and I’m looking forward to following his progress there.
‘It’s a great chance for him now and I do think he’s ready for it.
‘I do think he’s ready for League Two and to do well.
‘Hopefully he can do well. He’s ready for it now and that move.
‘For me as a manager it was too good an opportunity to pass up.
‘I wanted to try to take it because Adam’s and person I’ve got a lot of time for.’
Jackett feels there is still plenty of development to come from May and a stay away from Pompey doesn't mean his progress will not be closely followed.
He added: ‘He’s definitely not out of mind. It’s let him go, adjust and adapt.
‘Player development isn’t an exact science. A lot happens between 18 and 24. Players come on at different times.
‘Players can get a lot stronger, a lot more confident and basically physically grow into their strength.
‘Adam is a big lad but I’m not sure he’s always had the body strength of somebody his size.
‘If and when he gets to that and gets his confidence there’s definitely a player there.
‘I think he’s naturally a big lad and naturally a big lad anyway.
‘I don’t think he’s always had the strength for it but as he gets older he will, definitely.’