@JSM You’ll need eight hours of sun on the turf to get good growth. If the oak tree is older than three years old, you probably won’t be able to water deep enough to get to the root zone without over watering everything else. If the trees are healthy, they should be fine. A problem you may have depends on the soil build up around the oaks for the flower bed. Soil next to the tree’s root flare is not recommended.
Step 2: Remove Excess Soil and Mulch from the Trunk Flare
A very high percentage of trees are too deep in their containers, have been planted too low or have had fill soil, eroded soil and/or mulch added on top of the trunk flares. Soil or even heavy mulch covering the trunk flares block oxygen, keep bark moist and lead to circling and girdling roots. Ideally, excess soil and circling and girdling roots should be removed before planting. But - removing soil from the trunk flares of planted trees can be done professionally with tools such as the Air Spade or Air Knife. Homeowners can do the work with hand tools, stiff brushes, gentle water and shop-vacs or power washers if if done very carefully. Vines and ground covers should also be kept off tree trunks and pruned back away from the flares, at least on an annual basis.
Are you sure the soil is sandy loam?
You’ve got shade. Do you have slope?
Do single zones have a mix of fixed spray and rotors?
Looks like you may be zone/schedule challenged like a lot of other folks.
Welcome to the neighborhood!