Gardening within the root zone of a large tree is always a challenge, especially one like the Liquidambar (sweet gum), with an extensive network of surface and feeder roots. The roots outcompete smaller plants for any available soil moisture and nutrients and the tree when in leaf will often shield rainwater away from reaching the underplantings. Plants best suited to this type of environment are those that will tolerate dry and typically unfavorable soil conditions. Whether they need to be shade tolerant or can be more sun loving will depend exactly on how much light reaches this planting area but they will all need to share the characteristic of being drought tolerant. And they will need help initially to get established, with frequent deep watering and perhaps some nutrient supplementation through fertilizer or a layer of compost. One of the things you could try - in addition to a better suited plant selection - would be to enlarge the size of the bed. Using the sweet gum as an anchor for one end of the bean shape, draw the shape out so that the opposing end is well clear of the canopy. While the roots will still be present, the area will be more exposed to the elements, receiving more direct sun and rain. You could also raise the soil level in this area, which will give the new plantings a better start than digging directly into the rooty, nutrient-starved existing soil. You just need to be careful not cover the entire perimeter around the base of the tree with additional soil, as this can deprive the tree roots of oxygen and eventually kill it. But raising in it one particular area well away from the trunk will have no adverse effect. And a larger planting area will carry more impact than a smaller "ring" around the base of the tree. There are lots of drought tolerant perennials (and quite a few shrubs) that will grow in this situation, especially in a zone 7 climate. Google up some lists or visit a local nursery for their recommendations. Smaller sized plants will establish easier than larger, more mature ones (and they are far easier to plant when digging through compacted, rooty soil). Most annuals tend not to be the slightest bit drought tolerant so you may not have as much success with them. And often the plants best suited for these conditions are not the showiest with respect to flowering so you may need to dial down your expectations and focus on foliage or other long term interest. Good luck!

I'm sure you will get other responses with greater detail but here is where I would start. Be sure to pull those weeds by hand to remove the seeds from that area. Understand that tilling it up will bring other buried seeds up to the surface so you will be fighting weeds next year. Be sure to put a marker at any small plants you put in that area. I slice up milk jugs with a pair of scissors to make plant markers. This will help in weeding the area and a helper won't pull up your plants. If the soil has a good layer there you should not have to add more topsoil. And yes you should try to remove any large stones when it is tilled up. I purchase the composted cow manure called Black Cow. Look for a bright yellow bag with black printing at Lowe's or Home Depot. It is very inexpensive. About $2 per bag here in Virginia. It sounds like you may need three or four bags but you can judge for your planting area. Good luck with your project.

Ferns, hostas, astilbe (water, water, water), heucherella (just planted some pink ones and they look lovely), tiarella, hydrangea in place of burning bush, Dicentra eximia (native bleeding heart), native (deciduous) azaleas, carex are a few more ideas, well my favorites anyway. ;-) Not sure you can see the Pink Revolution heuchera too well here. They are around the bird bath which I cleaned and centered today. They were just planted and will fill out even more next year. If I can I will try to get a better photo tomorrow or Monday!

Ditto to the advice above. I feel your pain lol. I neglected my garden for about three years due to life getting in the way, and now I am trying to rehabilitate and revamp the beds. Don't feel you need to do it all at once. Do a bed at a time, or a section at a time. That's what I'm doing and I'm not quite so overwhelmed. That said, I would actually start with a plan, vague or sketchy as it may be. Think about how you want it to look, what kinds of plants you want (for instance, I'm transitioning over to more shrubs for less maintenance). At this point in the season I might even just clear out the weeds and replant the good stuff, put down some compost and shredded leaves, and wait for spring to do the bulk of the digging and planting. It's kind of amazing what a few months with some organic matter will do; on top of your existing-if-neglected garden bed, organic matter should make spring digging much easier. Then I would spend the winter doing some research to see what you really want. Maybe plant a few bulbs this fall for spring color, inspiration and motivation. Of course, I just realized this depends on where you live, if you have a winter, etc. Not sure where you are but if you are in a colder zone, I think this would be the way to go. Good luck! :) Dee