It helps to know your location and, if you don't want to tell that, your growing zone. It makes a big difference. Here in Vermont, my vegetables and flowers know that 50* F. means it's summer (almost)! And if you've planted tropical plants, who might actually object to temps in the 50s.
Unless you're planting tropical plants, you should be fine. It's too soon here to put out plants that can't tolerate frost (we are not supposed to plant until Memorial Day!) but my brassicas and lettuces (both from seed and starter plants) are happy out there. It was 38* F. last night. But all your regular garden vegetables should be fine unless there's going to be a frost. They might grow a little more slowly for a few days and then take off when the weather warms up.