Here in the desert of Phoenix, our traditional bermuda grass goes dormant and will turn yellow until the following spring. However, if you start to see scalping which can start in late September and go through to Halloween is so that rye seed can be planted so that locals can have a green lawn in the winter months. This grass will only last 1 cycle and usually die out by late spring but to plant this new winter lawn, you will need to have access to the soil and you will also want to minimize the view of the yellowing bermuda grass.  This process is known as overseeding.

What is overseeding? According to the article by the College of Agriculture & Life Sciences in the University of Arizona, Overseeding is the practice of seeding a cool-season winter grass into the existing bermudagrass lawn prior to it going into dormancy for the winter. October is an ideal month for overseeding. Overseeding too early when temperatures are warmer favors bermudagrass and prevents the winter grass from getting established. Later overseedings may be threatened by frost when young seedling grasses may be damaged.

How do you overseed your lawn? Prepare 30, 14, and 1-3 days before overseeding.

• 30 days before overseeding – Stop nitrogen fertilization of the bermudagrass lawn
• 14 days before overseeding – raise the mowing height 30-40% and decrease irrigation by 30%
• 1-3 days before overseeding – stop watering. Just before overseeding, lower the mowing height another 25-30% and leave the clippings as mulch for the overseeding seed DO NOT scalp the bermudagrass to the ground level.

On the Day of overseeding  – use ryegrass seed at 12-15 lb/1000 ft2. Apply one-half of the seed by walking in one direction and the other half of the seed by walking in a pattern perpendicular to the first pass. 7-10 days after overseeding  – irrigate 3-4 times per day to keep germinating seed moist. Finally 14 days after seeding emergence – Fertilize with ammonium phosphate (16-20-0) at 5 lb of product per 100 ft2.

When do you first mow?  When ryegrass height approaches 3 inches. When mowing make sure your grass is dry and that your blades are sharpened.

Do not forget to always water after applying fertilizer. Over fertilizing can increase likelihood of frost damage, disease occurrence, and necessitate extra mowing. 

How to maintain overseeding as spring approaches? Generally occurring during April to May, bermudagrass resumes growth as temperatures remain above 60°F.

• Encourage bermudagrass growth by lowering mowing heights by 35% and mow more often

• Apply nitrogen fertilizer weekly at a rate of 0.25 lb/1000 ft.

• Do not stop irrigating.

• Any drying could slow bermudagrass growth

• Once 80% of the lawn is established as bermudagrass, complete the transition by lightly verticutting to remove the ryegrass, apply 0.25 – 0.50 lb N/1000ft2 and decrease watering for one week. Repeat the fertilizer application and water cycle to put stress on the ryegrass.

• Aerify bermudagrass during late June, July, through August

During the summer, bermudagrass should grow for 100 days to establish and grow vigorous roots and rhizomes. After 100 days of active growth, overseeding may be accomplished successfully.