Between May and September you'll probably notice your lawn has grown at twice the rate it does during the winter months. Warm season grasses love the warm, wet weather. Most people thought the hot weather would keep the grass from growing well, but remember warm season grasses optimal growing temperatures are between 90-105 degrees. During this season any of your weaker areas should have filled in with the warm season grasses runners. These spots can be slow to fill in during the dry, hot days but as soon as the humidity kicks in the grass really takes off. If you still have large open spots I would suggest picking up a few rolls of sod and patching them prior to overseed. You don’t want to seed directly into the soil.

During the summer months you’re getting lots of new growth on the grass plant and you need to help it thrive. The best way to do this is to thin out the top growth by using a verticut or power rake. Most people only use one during the overseed season but it’s a vital part of promoting new growth during the summer months. When you get too much top growth the grass will get clumpy and keep your new plants from growing. A verticut or power rake will open the turf canopy and thin out the grass plant. Doing so will promote new plant growth. This will also allow you to mow your lawn shorter without scalping. Set the power rake or verticut about halfway down and run over the entire lawn. You can easily mow or rake up the material. Keep in mind that by thinning it now you will save yourself hours of labor during overseed. If you wait until overseed to thin your lawn you may need to repeat this process several times.

For the next month you don’t want to promote top growth unless you don’t plan on overseeding this fall. The more material you have, the more material you will need to remove during overseed. I like to stick to slow release nitrogen products or products that will promote root growth during late summer. There are lots blends that will work but phosphorus and potassium will help your roots at this time of the year.

It’s still too hot to really cut back your water but during the wet periods you can let the lawn stress before you turn the irrigation system back on. Let the lawn go until you see some bluish grey spots appearing in the lawn. These areas aren’t dying but they are stressed. When you see these spots you know it’s time to water again. You can start to back your water down in mid-September when the nights cool off a little more.

If you’ve had persistent weed issues during the winter months you can apply Prodiamine. One product that a lot of people use is Barricade. This must be used 7 weeks prior to overseed. Keep in mind you must wait 7 weeks after you spray this product before you overseed. For the first two weeks of overseed you will need to keep the seed a little more wet than usual so the roots of the new plant can break through the Barricade layer. If you sprayed this week it would have you overseeding in the middle of October which is perfect. The best overseeding period is typically from October 7th-October 31st. Any time you seed during this time frame you will have very little competition from the underlying warm season grass. If you go earlier be prepared for the warm season grass to come back and be actively growing while you’re watering the ryegrass seed.

One way to keep the warm season grass in check is through applications of plant growth regulators such as Trinexapacethyl. One such product that many use is Primo. This can be applied 5-7 days prior to overseeding at .5 oz/1000 SF and right after the first mowing at .35 oz/1000 SF. If you seed during the normal window in October you can skip this step unless you have a very lush, over fertilized lawn going into fall. This is not an endorsement of these products but a generic list of products you can try.

The final thing you can do is mow a little lower for the next few weeks and reduce the turf density. Right before overseed I will tell you to let the grass grow up about 30-40% prior to scalping but you have over a month until you need to worry about it.

Remember when you start to see seed in the stores you want to find a perennial ryegrass that is weed free, and has a high germination rate. Many of the products you will see will be cheap in cost and won’t provide you with a dark green lawn during overseed. I will put out overseed instructions in September as we get closer to the season.

If you have any questions, please hit the "Ask Jay" button at the top right of this page.

Till next time,

Jay