The "dog days" are the hottest, muggiest days of summer. In the northern hemisphere, they usually fall between early July and early September. The actual dates vary greatly from region to region, depending on latitude and climate. But, fall is coming.

Did you notice that you got to skip a mowing and that some of the trees are starting to turn rusty-colored?

In ancient times, when the night sky was not obscured by artificial lights, the Romans used the stars to keep track of the seasons. The brightest constellation, Canis Major (Large Dog), includes the "dog star," Sirius.

In the summer, Sirius used to rise and set with the sun, leading the ancient Romans to believe that it added heat to the sun.

Although the period between July 3 and Aug. 11 is typically the warmest period of the summer, the heat is not due to the added radiation from a far-away star, regardless of its brightness. The heat of summer is a direct result of the earth's tilt.

Spending time outdoors this time of year is uncomfortable, and potentially dangerous, due to the intense heat. However, the chinch bugs are very active in St. Augustine grass (see http://edis.ifas.ufl.edu/lh036 for details), and the summer flowers need water. So, take care of those tasks early in the day and then retreat to the air conditioning to plan your fall planting.

Plant tomato plants in August for tomatoes in October. Varieties such as Phoenix, Florida 91, Solar Set and Heat Wave II are good selections for setting fruit in high temperatures, should summer temperatures continue. Otherwise, try some of the newer varieties recommended for fall planting by the University of Florida's Institute of Food and Agricultural Sciences. These include Bella Rosa, Tribute or Finishline. Refer to http://edis.ifas.ufl.edu/in756 for more information on tomato selection. Refer to the Florida Vegetable Gardening Guide, http://edis.ifas.ufl.edu/vh021, for information on other vegetables for fall gardening.

Many bedding plants flower quickly and can add color to the fall landscape. These include pentas, African marigolds, torenia, zinnias, melampodium and scaevola. Other can be planted in October for blooms all winter-long. Plan spaces and color themes for calendulas, pansies, snapdragons and violas. Add in ornamental cabbage or kale and some dusty miller to accent the garden. They too will perform through the cold.

See http://edis.ifas.ufl.edu/mg319 for more on Annuals for the Florida Garden.

Dependable fall blooming perennials include lion's ear, pineapple sage, firebush, cigar plant, yellowbells and firespike. Also, garden mums and many different irises will add color again in the spring. See http://edis.ifas.ufl.edu/mg035 for information on perennials.

Webster's second definition of "dog days" is a period of stagnation or inactivity. But, even when the heat forces you to slow down on the labor-intensive work, there is plenty of gardening activity to do. Stay in the air conditioning and plan that spectacular fall and winter yard.

Sheila Dunning is an agent at the University of Florida's Institute of Food and Agricultural Sciences Extension office in Crestview.