the roots will be fine in the earth.....if your planting in pots with two or more plants, thats when you should be concerd about root space. outside will be fine for roots, side shoots and 2ndary growth might be a concern. but like stinky said try and train them away from eachother. although i have seen a lot of plants crammed into a green house with great results, its still best to let them have their space....helps airflow through out the plant.