I assume you're talking about putting established plants outside rather than just starting germination at that time. Middle of may SHOULD be fine to put outside assuming your exact location is getting plenty sunlight, all danger of frost has passed, average daily high temps are in the 70ish range, and ideally lows average no colder than 50ish...but the warmer the better. Established, plants that have been properly hardened off will have a much better chance of survival than small seedlings. I'd say grow them inside until they have at LEAST 4 nodes but preferably 5 or 6.
Look up extended forecasts, monthly averages, farmers almanacs and the such on the web to get a good idea of yearly averages in your area for that time period. Also keep in mind outside there are other things to consider such as if you have a "severe weather season" in your area, or certain known pests that are abundant at that time. I think the most you would want to try to plant in a square meter (I think thats what u meant...1 meter/sq) would be maybe one or two. But I have no first hand experience with that strain (yet) so perhaps someone else who does would know different. I'm growing some of those this year myself and I'm only several degrees lat off from you. You can find my thread listed in the outdoor/greenhouse forum titled "Shadowbucks go at an outdoor grow." But first please go to the forum titled "Introductions" and introduce yourself (if you have not done so already) to the AFN fam. Be as personal or discreet as you like but in my own personal experience here, I had A LOT of people come read my intro post and welcome me here. And a lot of the same people have since helped me out greatly with questions I have had. But anyways, welcome to AFN! :smokebuds: