well if you have a good spot with at least 5 hours of direct sunlight, its going to dry the soil out. your going to need to water at least twice a week during summer. try mulching them with about2 inches of mulch. this will keep the soil cool and moist during the hot summer and keep it warm during the spring and fall. pots will dry out faster than soil in the ground. try adding a little bit of vermeculite or silica crystals to your soil but not too much you dont want soggy roots. dig holes about 3 feet by 3 feet by 3 feet for each plant. try to find an area that the soil looks dark and breaks apart easily in your hand. you want to mix your good soil with the native soil in the bottom of the hole, then add your good soil for about 6-8 inches, then plant your plant in the good soil, you want a buffer zone so that when the roots grow thru your good soil they dont hit pure shitty soil and get shocked. another thing you could try (if your not trying to be super stealth) is take a 5 gallon bucket (clean of course) with a lid. drill a small hole (around 1/16" - 3/16") in one side right at the bottom of the bucket. put this bucket beside your plant full of water (and nutes if you are feeding) and it should drip for a day or two, this will porlong time between watering.
anyway hope this helps
goodluck