Around the beginning of April, the nurseries are flooded with new annuals and perennials for customers to lap up--- unfortunately, we have some cooler nights around here in the Pacific Northwest, so it is VERY wise to check the night time temperatures before purchasing any tender annuals.
I have learned my lesson losing plants during cold snaps. Geraniums and Non-stop begonias are my biggest worry; I also have concern for tomatoes as I have (on more than one occasion) placed them out too early and they end up stunted and are very low producers. I suggest that you purchase tender plants once all fear of below 45 degrees F has passed. I am looking at the forecast now and there are still some chilly nights ahead so I am going to wait on putting my tender begonias out for now. I also will wait on putting tender houseplants out too.
Houseplants are a little more tricky to bring in and out during warmer months. They need to essentially "harden off" to be accustom to their new environment. The house temperature rarely has large fluctuations in temperature and humidity, while outside, things are much different. It can take me a week or two moving plants out in the morning and in at night to help them adjust. My lemon and lime trees are chomping at the bit to go outside, but it is still a little too cold.
if you have any questions or comments, please feel free to contact me any time at NWBotanista@gmail.com