6 month old napping

[Smunchy]

Hi Everyone,
I have a 6 month little boy, who only takes very short cap naps during the day. Because he only takes short naps, they are usually 20 minutes long, he is getting tired and has to go down for a nap roughly every 90 minutes and is very grumpy by bed time (6:30pm).
Is this normal, is there anything I can do to make him nap longer? I feel like I'm doing something wrong.....any advice would be greatly appreciated

[CityDweller]

Mine was like that! She'd nap for longer in the pram at that age (up to 90mins at times). So we'd do that for at least one nap a day. Then I started re-settling her when she stirred if she was taking her longer nap in the cot. Would involve picking her up and rocking her for 15-ish minutes until she fell asleep in my arms and then doing that inching-sleeping-baby-into-cot-thing, but then she'd often go back to sleep for another hour or so. Was worth all the ridiculously massive amounts of effort I put in as now (1yo) she's a champion napper (something I never would have predicted as she was utterly crap at napping for the first five or six months)