Turning point: When is it safe to plant garden? Spring in the vegetable or flower garden is a carefully orchestrated series of events By LEE REICH, Associated Press Published: May 15, 2021, 6:05am Share: This undated photo shows tomato being planted in a garden in New Paltz, NY. One week after the "average date of the last killing frost" for your garden is the time when it's generally safe to plant out tomato transplants. (Lee Reich via AP) Spring in the vegetable or flower garden is a carefully orchestrated series of events. The goal is to keep things moving forward with the warming season, taking into account weather predictions and, because those are just predictions, average spring warming trends where you garden.