Late January, believe it or not, means warmer weather for lawns in Phoenix, Tucson and Yuma. Many overseeded lawns are a multiple of colors at this time. This is due to cold weather (mainly frosts) and differences in soil depth and drainage patterns. In late December and January, the cool season grasses are often on the verge of going to sleep (cold induced dormancy). The lawns appear to be "growing better" in different areas than others. In a nutshell, here are plausible reasons for the following conditions.

This is usually caused by cold temperatures in a slightly under fertilized lawn, which has been planted (or ended up) with a high seed rate. The extra competition resulting from the higher seed rate. Here the lawn looks thick, but each plant is actually a single skinny tiller (a single shoot, or two tillers at the most), with narrow leaves. Quite often, this turf is light green in color, with yellow leaf tips. The turf will "look nice" until it gets hot in August. Then it will fade quickly and have a delayed bermuda green up because it was smothered by the "thick" overseed.

Even though the lawn is mowed regularly, the lawn may appear to have straw colored leaf tips. It may even look tan to silvery across the entire lawn. This is very common on tall fescue lawns at this time. The cause is accumulated and moderate frost damage. Resist the temptation to mow off the damaged leaf tips by lowering the mowing height. You will simply scalp the lawn and make the condition worse. Simply fertilize the lawn with 1/4-1/2 lb. of a quick release water soluble nitrogen form. The "new" growth will be mowed off, accordingly.

For winter grass lawns, this usually is the result of a low population density caused by either too low a seed rate, or poor germination from unequal irrigation. Tall fescue, perennial ryegrass, and even to some extent Kentucky bluegrass will all show this response. When grasses have "extra room to grow" (no neighbors close-by), their leaves are usually wider. This lets them catch more sunlight per plant.

If the ground doesn't have a lot of bald spots, simply fertilize and mow. If you reseed by hand, don't put more than 10-15 seeds per square inch on the bald spots.

Here is a classic turf response of over irrigated wet spots, or poorly drained run-off areas. If the irrigation system is applying water evenly across the yard, than you are applying too much water. Adjust the run times on the lawn timer. Take a pitch fork and push it down into the grass and shake it side to side. Chances are the tines (forks) will go deep and the soil will offer little resistance. Leave the holes open. Do not put sand on top of the grass.

This is the result of too much late fall and early winter fertilizer. When the soil is cold, the fertilizer is either not taken up, or not expressed as growth when the air temperatures are cold. Now, when it's warmer (either January or February), the lawn will want to grow like mad. You have to mow the lawn more often, or raise the mowing height. Otherwise, you will scalp the lawn and end up putting on more water and fertilizer to fix a man-made problem.