Meanwhile Zagreb and Ljubljana are quite well connected buy bus, especially during the summer season there are several daily departure, current schedule can be found at the buttom of this page. Busses from Ljubljana to Zagreb can be found here.
The easiest way to get to Ljubljana is definitely by car. If you don't have your own vehicle we recommend a one way rental from Zagreb or Zagreb airport, you can see current rentals offers from Zagreb here.
Other means of transportation
1. By train – there are several daily direct trains between Zagreb and Ljubljana. A One-way ticket between Zagreb and Ljubljana cost about 14 Euros and the return ticket about 22 Euros. Duration of the train trip is about 2 hours 20 minutes. From the main train stain Kranj, you have frequent airport bus to Ljubljana airport.
2. By car - driving by car from Zagreb to Ljubljana is fast and easy, as there is highway end to end between the two cities. The travel distances on the shortest and fastest route is 139 km, which equals a travel time of about 1 hour 30 minutes. In Slovenia it is important that you remember to buy a vignette, otherwise you risk to get fined. On the map below we have marked the main as well as an alterative travel route
3. By plane - not available