What I do is "cool down" most of my temperate zone animals (Cynops, Triturus, Taricha) in sort of a wintergarden during fall and winter. Temperatures go as low as 3 deg. C.. I keep the animals aquatic in tanks with lots of hardy vegetation (e.g. Egeria or Java moss with cork bark islands). This wont work with all Triturus species though. I even feed carefully at low temps. Breeding success has increased since I do this regularly.
I don't do this for Tylototriton verrucosus (obviously), Pleurodeles, Paramesotriton and Cynops ensicauda. For the latter two, slight temperature variations (decrease during the colder period of the year) seem to be sufficient to induce courtship and even reproduction (temps going down to 14 deg. C. during winter).
I've heard of people breeding temperate zone caudates who supposedly don't do anything. When "interrogated" thoroughly though, slight temperature variations have also to be assumed for these setups. However, some sort of domestication effects in animals being kept and bred in captivity for generations have also to be considered (loss of fixed reproduction periods).
Apart from hibernation and photoperiod I experienced that employment of high energy feeds (e.g. pelleted trout feed, white worms) after periods of regular feeding at low levels seems to favor or even improve courtship and reproduction.
Ralf