These types of plants will often be listed under plants for xeiroscaping - which means plants that will survive with little or no watering. If your garden is somewhat more demanding, you are probably going to need a good friend or neighbour to help out when you're away. But their job could be made easier by following a few rules of thumb. Not only does clay soil hold more water, it retains water longer than sandy soil. Soil dries out more quickly on slopes, especially those facing south or west.
Herbs can withstand very dry conditions.
Water only when they begin to droop. Shallow-rooted crops will need more frequent watering than more deeply rooted crops. Try to plants crops with similar watering needs together. Raised beds can dry out more quickly than regular beds, usually because they have better drainage. Plants in raised beds are often grown intensively - that is, they are planted more closely together.