It is possible to get three harvests from strawberry plants Spring 1. This requires using Speed-Gro and planting on Spring 13, and the easiest way to do this is to complete the spring crops bundle; this requires planting cauliflower day 1 as well as visiting the Community Center after the Egg Festival before you plant the strawberries. The other way to aquire Speed-Gro by Spring 13 is to craft it, but this requires achieving level 3 foraging by Spring 6 to acquire pine tar in time, which is more difficult.