Many people believe that fall begins the day after Labor Day.
Others believe that it really begins on the day the Autumnal Equinox falls.
As a groundskeeper I believe that fall begins for the gardener about the second week of August.
This is the time which I start a lot of my fall gardening activities.
I know it may sound strange to some, but for those who know it is a great time to start projects and fall maintenance that gives you a few extra weeks head start.
In The Planting Beds

• Divide Perennials - Perennials such as hostas, day lily, cone flower, and may other perennials can be split and divided now.
  The plants will have a long period of cool moist fall weather to help them get established by winter.
  
• New plantings can be done to add to your beds or change them.
  Getting plants in now will get them well established by winter.
  
• Prune up roses and other shrubs to get them in a more uniform shape.
  
• Work up the soil and apply pre-emergent herbicides to discourage fall weeds.
  

In The Vegetable Garden

• Set out fall crops such as broccoli, cabbage,and kale now.
  
• Clean out and remove dead and dying plants.
  
• Plant onions, radishes, spinach, and other cool season crops.
  
• Keep the soil worked up in bare areas to discourage weed establishment.
  

On The Lawn Lawns usually take a beating during hot summer weather and have a need for attention to start looking their best again.
If there are areas where there are large sections of mostly weeds then these areas should be killed off with an application of a weed killer like roundup.
Be sure that it has no residual effect and it is systemic (goes into the plants and kills the roots).
Apply this per label instructions.
In about a week you will seeds the weeds start to turn yellow this is your cue to prepare to renovate this area.
Rent a power rake and go over the area three or four times.
This will pull up a good portion of what ever vegetation was there.
Remove all the debris and then spread a good seed mixture over the area with a fertilizer spreader about four pounds per thousand square feet.
Next apply starter fertilizer according to label directions.
The final step is to spread a quarter inch of peat moss over the entire area and water thoroughly.
Keep this area moist for the next six weeks and you will have a good established lawn by the end of fall.
For less severe areas you can do core aeration in September along with an over seeding at that time.
If you turf is very thick and spongy you may want to de-thatch it first using a power rake.
Run the power rake in only one or two directions once you are through cleanup the debris and remove.
Then you can do core aeration and over seeding