Certified GKH Gardening Expert
The best way to ensure deep watering is to ensure that the soil contains aeration. Fixing drainage problems once the plants are established can be a little more difficult.
Sometimes, poking holes in the ground, deeply, or removing small plugs from the area can help with drainage issues at the top of the soil level. Adding earthworms to the area can, also, greatly increase soil aeration.
Here is an article that will help you with this task: