It will be quite a chore to grow grass in those areas. They are probably full dense shade. I have a spot just like that. Given that your renting what do you want to do with the area? In the long run, hardwood mulch and some shade loving plantings are your best choice. This fall you could try some fine fescue. First thing will be to pull or use a herbicide on the weeds. Make sure you can identify poison ivy and poison oak - that may be what is growing on your tree in the first picture.

In your area St Aug would be my first thought. It can take over in my opinion. All you have to do is put down one piece (about a dollar). If you can get Floratam use that but I think all you can find is Palmetto in your area. Put it down onto bare soil and walk on it to get good contact with the underlying soil. Keep it moist for the first 2 weeks until it knits to the underlying soil. Moist means moisten (not drench) it at breakfast, lunch, and dinner. Once it is established keep it just a little bit moister than the surrounding Marathon II. Marathon II is a dwarf type grass. Palmetto likes to be mowed at the highest setting. If you mow your lawn at the highest setting and restrict water to once per week (that is after you are sure your piece of St Aug is knitted down), the St Aug will send out runners in all directions about 5 feet in length once during the warm up in the spring and once again during the cool down in the fall. So you'll get a pretty good coverage. When you fertilize, fertilize only the St Augustine. Drop some alfalfa pellets on the main piece and follow the runners out with more alfalfa pellets. You can do that every week if you like. That will keep the St Aug in the peak of health while allowing the Marathon II to decline. If you have patches of burr clover now, that is right where I would start with the St Augustine pieces. The more pieces of St Aug you start with, the faster this project will be complete. In the really hot and dry summer heat, meaning over 100 every day and humidity below 20%, you should water the St Aug every 5 days. Just to keep the Marathon sort of green, that should probably be watered, too. As the temps cool down, you can favor the St Augustine more and try to get more runners out of it. If you buy one piece of St Aug for a dollar, you can chop it up into smaller pieces with a machete or shovel. I would not cut it into more than four pieces, though. You have to have something to work with. But that would help you get it going farther faster. Generally St Augustine will dominate all other grasses with few exceptions. Some bunch grasses like dallisgrass can get a foothold and move in. Burr clover can be a weed in St Aug. Once you get St Aug, you can no longer use Weed-B-Gone Clover, Chickweed, and Oxalis against broad leafe weeds. WBG will kill the St Aug. You have to use a product with atrazine. You can only use that stuff once per year, so be judicious when/where you use it. Atrazine is a nasty product and repeated use doesn't seem to work as well as the first use anyway. When you spray, walk backwards so you don't have to walk through it. That stuff will flat knock down everything but the St Aug, though. It can take a few weeks, and you'll never really see the weeds withering away until SUDDENLY (!) they are no longer there. I would wait until April when the grass and all the weeds are growing well. Don't spray it now or you might lose your entire lawn. This paragraph is more for next year and the years after once you have the St Aug established. If you are watering and mowing right, you should never see another weed.

+1 Tiemco. I have written two postings in the past two days for folks that wound up with difficult-to-treat weeds after using big-box seed mixes. It's penny-wise and pound-foolish to save a couple of dollars on seed and then wind up having to purchase specialty herbicides to kill the weeds (the herbicides cost $50-$130). Purchasing really good (sod-quality) seed lowers the follow-up work that can go on for 2-3 years. It's similar to purchasing knock-off parts to repair your car - it may work or it may backfire and cause other problems. Also consider that disease-resistance is much better in the newer cultivars, which avoids the do-it-again-and-again cycle of repairing the lawn. This post was edited by andy10917 on Sun, Dec 9, 12 at 9:56

In terms of excess moisture, I just poked around a bit this morning on my way to work and noticed that the soil in that area was very wet. I also noticed lots of little bugs flying around that area! Also should add that a couple mushrooms have popped up in other parts of the lawn. With that in mind, I'm thinking a fungus has attacked the KBG and is leaving the fescue plants alone (so far). If you are not watering like the following paragraph describes, you should go there gradually over the next month. Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, sprinkler and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall.