Seeding your lawn with Bermuda grass for the summer and rye grass for the winter is a popular practice in the southern United States, including Texas. While Bermuda is a warm-season grass that stays bright green most of the year, when fall temperatures drop, it browns immediately. Rye grass, on the other hand, is a cool-season grass that provides a green lawn through mild winters and dies in summer heat. After rye has died for the summer, it can pose questions about lawn treatment, especially if it is a perennial variety, which doesn't die as fast as annual rye grasses in the spring.
Fertilize in the spring to make sure your Bermuda grass has the strength it needs to take over from the rye grass. The rye grass has been using soil nutrients throughout the winter, so the Bermuda coming up will need an extra boost to grow strongly. Use a high-nitrogen fertilizer, like 15-5-10, that is labeled as slow-release, to give the Bermuda sprouts long-term nutrients.
Mow the Bermuda-rye mixture short before the Bermuda greens up. This should be done sometime in March in Texas; after the last freeze is past, mow the grass down to 3/4 inch high, but not below 1/2 inch, and bag the clippings for mulch or compost later; don't leave them on the lawn. Once the Bermuda grass greens up later in the spring, mow higher, at about 2 inches to 1 1/2 inches, depending on the recommendations for your grass variety.
Water regularly. Bermuda grass takes a lot of water at the beginning of the season, as much as two or three times a day to keep the soil moist. However, if the temperatures are cool, this may discourage a good transition from rye to Bermuda, so you may have to wait to kick up the watering until summer heat arrives.
Maintain the lawn with conditions favorable to the Bermuda grass, rather than the rye. Water frequently, at least once a week, and more often when there is no rain. Mow regularly, not cutting the grass below a third of its height at any one time.
Dethatch and aerate. If the dead rye is unsightly for an extended part of the summer, use a combination of dethatching and aeration in the late summer or fall to get the dead grass out of the lawn. Dethatch first, whether with a machine or a hand rake. Aerate afterward, with a hand aerator or a machine.