Warm-season Turfgrass – To Overseed or Not to Overseed

Overseeding with a cool-season grass like ryegrass can make your lawn look very nice in the winter, but do the aesthetic benefits outweigh the risks? Ultimately, the decision is yours, but there are some legitimate concerns.

If you were not able to keep your grass well-watered and actively growing all summer, you may want to think twice about overseeding. Planting winter grass before the permanent grass goes dormant in the fall causes additional problems for your drought-stressesd turf. The winter grass deprives the existing grass of the last month or so of its normal growing season by shading it out and competing with it for water and nutrients. Speaking of nutrients – the addition of fertilizer to the cool-season grass can further harm the warm-season grass by encouraging weak growth far too late in the fall, setting the stage for winter damage.

Another reason to avoid overseeding comes next spring when the warm-season grass is breaking dormancy and beginning to grow. If an overseeded grass is present, it competes for light, water, and nutrients with the underlying grass, thus inhibiting growth. For this reason, it is very difficult to achieve satisfactory results year in and year out when overseeding your warm-season turfgrass.

Trees

While fall isn’t the only time for planting trees and shrubs, it is definitely one of the best. Why is that? As the temperatures cool, evergreen and deciduous trees and shrubs go dormant and become less active. However, the winter temperatures of our Alabama soils are still warm enough to promote root growth. When spring arrives, this increased root system is better equipped to access water, thereby drastically reducing the stress of transplanting.

Even though we are a month or so away from ideal planting time, take this opportunity to plan what you will plant. When it comes to trees, bloom time, bloom color, growth habit, and mature size are all factors that should be considered. One other element to think about is fall color. Although temperature and moisture affects and limits the timing and degree of fall color in Alabama, the incorporation of trees with proven autumn hues helps to create year round interest in the landscape. Many of our native trees provide excellent color. Don’t forget about the evergreens! Pine, cedar, and holly, to name a few, also have their place in the landscape as they provide a great background to make the vibrant colors of neighboring trees really pop!

Time to Lime? Test Your Soil First

Yes – this month is a great time to lime, but are you sure that your soil needs it? Applying lime when it is not needed can cause problems for your garden or landscape. The only way to be certain is to test. A soil test, which should be conducted every three years, will determine your soil’s pH and fertility levels, thus letting you know if a lime application will be beneficial.

Why is pH important? Soil pH directly affects the nutrients available to plants, and is a gardener’s most important analysis from the soil test. In our region, soil pH is generally acidic. These acidic levels are great for some plants, but greatly inhibit the growth and development of many others. Liming is often necessary to correct these levels. Because of the length of time and amount of moisture needed for the lime-soil reaction to take place, fall is an ideal time to test your soil and begin preparation for next year’s planting.

There are several potential sources of lime – burned lime, dolomitic limestone, and pelletized limestone are just a few. As you might suspect, each has its advantages and disadvantages. Burned lime is a fast-acting form of lime but can be hazardous if used incorrectly and is difficult to apply. Dolomitic limestone is a slower acting material and is also a source of magnesium. Pelletized limestone is easier to apply, but is usually more expensive than other sources.

In addition to providing pH, a soil test will give lime application recommendations. The rule of thumb is 100 pounds of lime evenly applied over 1000 square feet to raise soil pH by one point. It is recommended this amount should be the maximum amount applied at any one time. For example, if your lawn’s pH is 4.5 (very acidic), a series of applications, one month apart, should be considered. After all applications are completed, additional lime should not be added until another soil test is conducted in three years.

For more information about this topic or other horticulture-related topics, please contact Regional Extension Agent, Bethany O’Rear, by calling the St. Clair County Extension Office at 205-338-9416 or her directly at 205-612-9524.