I had a few landscape firms come out to one of my properties. I was looking to get a very very low maintenance solution for the lawn. How often should we airrate our lawn. What's a good organic fertilizer to put down at the same time of the seeds (tall fescue)Organic will not burn the seed correct? Also they mentioned a really invasive tree that's going throaght the hedges. Is there such thing as tree of heaven?
Ailanthus altissima, tree of heaven is invasive and you should remove it. See the fact sheet from Weeds Gone Wild on removal. http://www.nps.gov/plants/alien/fact/aial1.htm
You did not mention the type of grass you are growing. Turf type tall fescue is a cool season grass that grows in full sun to part shade and is the most disease and drought tolerant.
A low maintenance solution for your lawn consists of testing your soil every 3-4 years for pH, liming, and nutrient deficiencies; overseeding and fertilizing your lawn in the fall for cool season grasses(You should be aware that Maryland now has a lawn fertilizer law. This also applies to commercial companies too http://mda.maryland.gov/resource_conservation/Documents/fertilizerwebpage.pdf ); and mowing at the proper height. The most difficult aspect of a more natural or organic approach to lawn care is controlling weeds. The least toxic method is hand pulling. You will have to decide if you want to tolerate the weeds.
Usually the best time to perform core aeration is in the fall. Aeration opens the soil up to allow air, water, and fertilizer to penetrate and roots to grow. See our publication for more information http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG102%20Lawn%20Estab...
You may want to look at our Turfgrass Maintenance Calendar for lawns. This calendar offers monthly lawn care steps as well as a fertilization schedule http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG112_Turfgrass_Main...
There are many types of organic fertilizers such as Milorganite, Espoma, etc.