Certified GKH Gardening Expert
You could try the automatic waterers; however, you may want to let a neighbor or family member keep an eye on the garden while you're away, as there is a chance that the waterers could malfunction. This article should also offer some suggestions: https://www.gardeningknowhow.com/garden-how-to/lifestyle/out-of-town-garden-woes-tips-for-travelers.htm
One last thing - I didn't address your question about automatic watering. I don't like the idea of leaving the water on waiting for a timer but that's just me. Depending on how big your garden is - a trusty neighbor can water everything thoroughly within 30-40 minutes and not have to do it again for antoher two days and if it rains then skip a day or two. I find this to be one of the most relaxing things to do on a nice summer day...
You did not indicate when you will be gone or how long which will determine what to do. Note: in MD it rains so much/so hard that watering is almost a secondary act. However, if it's a new garden you must water well during late June (2-3 x a week, as well as in July and August. If it rains that week then only once about 2-3 days after the rain. I maintain fairly hardy plants that do well w/o water and have grasses and annuals on the deck that I rarely water letting the rain take care of them most of the time. I recommend asking a trusty neighbor to care for your plants. Most folks are glad to do this as long as you give them explict instructions - pls seek a fellow gardner not a novice.