As we head toward the end of summer, lawn care crews are preparing for overseeding to maintain green grass through the winter.

First, let’s discuss the initial lawn prep. Let your lawn grow up 25-30% in height to provide more leaf density. Another bonus of maintaining your lawn at a higher height is that it will use less water, and when you scalp your lawn it will leave plenty of healthy new leaves for the spring. If you have a healthy lawn, it’s good to go through and lightly power rake or verticut the lawn at this time. This opens up the turf canopy and allows seed to get into the ground. If you normally keep your lawn at 1”, you would want to raise the height of your lawn over the next two weeks to around 1.25”. When the weather cooperates, you can then scalp the lawn slightly below your normal mowing height. Most rotary lawn mowers can be lowered to ¾”. 

Remember not all seed is created equal. Here are some tips to keep in mind when looking at a bag of seed.

  1. The best material for winter overseed is perennial ryegrass. While it seems like the name annual ryegrass makes sense, it does not have the vigor, color, or density of perennial ryegrass.
  2. Germination Rate – The germination rate will tell you how much of the seed is viable. If you pick up a bag with a 60% germination rate then you need 40% more seed to put down the correct rate. You want to find a bag with over 85% germination.
  3. Weed Seed – This number should be zero. Any weed seed or inert matter is going to wreak havoc on your overseeded turf.
  4. Often times blended ryegrass seeds are cheaper because they put different grades of seed in the bag. Some blends are very good seed and provide different plant protections, but some mix in lower grade seed. Remember ryegrass seed is priced by germination, weed seed, and quality of the seed. Therefore, if you’ve found a deal on seed, it’s not always your best bet.

Overseeding materials

  1. High quality perennial ryegrass seed. 
  2. Starter Fertilizer – When you pick up your seed, also pick up a starter fertilizer. Some good ones are Soil Burst 4-4-2, 11-52-0, or 6-20-20.
  3. Second Fertilizer application -This can be applied after you have mowed the grass for the first time. Fertilizers to consider are 21-7-14, 11-52-0, or 6-20-20.
  4. All of your sprinklers should be working and properly adjusted. Check all of the nozzles after you scalp for any chips or dings that the mower may have caused by cutting shorter.
  5. Power rake or verticutter. 

Overseed Instructions 

  1. Cut back your water 25% two weeks prior to overseeding. Stop all fertilizer applications four weeks prior to seeding.
  2. Raise up the height of your lawn 25-30%. You do this so when you scalp the lawn it is not being mowed down to the dirt, instead you’re scalping to a manageable height for the turf, and it will not cause any injury to the turf in the spring.
  3. Power rake or verticut the lawn. Do not set the machine to dig up new rhizomes from the soil. Your goal is to open the turf canopy.
  4. After you power rake, mow up the clippings. The lawn mower works really well for picking up the grass. Next set the power rake a setting lower and do the same process in a different direction. This will open up the dense turf canopy and allow the seed to get into the grass plant.
  5. Mow the clippings again. After the clippings have been cleaned up, set your mower to ¾” or ½” if you have a reel mower and scalp the lawn. The only reason you’re scalping is to keep the warm season grass from competing with the ryegrass seed.
  6. As soon as the lawn is cleaned up, apply your starter fertilizer. You’re looking for a phosphorus application to help the seed. Some great fertilizers are 4-4-2, 6-20-20, or 11-52-0 to get your lawn started.
  7. I like to keep my rocks and edges clean so I use a drop spreader. Apply perennial ryegrass at 10 pounds per 1000 SF around the perimeter of the lawn first. Do two passes to ensure the rotary spreader will not throw seed into the rocks. This is not necessary but it will keep the ryegrass from invading undesirable areas all winter.
  8. Next apply your perennial ryegrass with a rotary spreader at 10-12 pounds per 1000 SF to the remainder of the lawn. If you want the best coverage you should apply 5-6 pounds of seed per 1000 SF in two directions. This is always the best approach but again not necessary.
  9. You will have some seed on top of the grass surface but the majority should be inside the grass plant if you prepped your lawn correctly and opened up the canopy. You can use a broom to help any additional seed get into the plant.
  10. Follow watering instructions below

Some people cover their seed with mulch, but you can save your time, money and the smell in your yard because this isn’t necessary. Mulch allows the seed to maintain moisture and keeps the heat in the plant but if you’re seeding in September/October there is plenty of heat. You don’t need to worry about the moisture either. Mulch doesn’t prevent birds from eating your seed and even if they do eat some seed you have already applied plenty of seed with the 10-12 pound/1000 SF rate.

Watering your overseed lawn

Week 1-2: Water 3x daily for 5-7 minutes per cycle. Make sure you don’t have ponding. If you do, lower the amount of water. I suggest watering around 8am, noon, and 4pm.

Week 3: Water 2x daily for 12-15 minutes. Since the plant is very new at this time a morning and afternoon application is best. You can typically mow the lawn for the first time after 14 days. It’s best to let the grass dry down for several hours prior to making the first mow. Keep the mower set at a higher than normal height, do not scalp the grass.

Week 4: Water 1x per day for 10-15 minutes. During this time frame you can mow every 5-7 days.

Week 5: Water every other day 10-15 minutes. Mow your lawn every 5-7 days as needed and make one more application of Soil Burst 4-4-2, 21-7-14, or 15-15-15.

Week 6 and beyond: Water every 2-3 days as needed until the temperatures cool off for the winter. During the winter you can stretch your ryegrass even longer between watering. I would suggest fertilizer applications every 28 days throughout the fall. When temperatures drop around freezing, it’s best to use liquid fertilizers to maintain turf vigor.

Jay Danek
Mr. Wise Grass

11803 E. McDonald Drive
Scottsdale, AZ 85256