St. Augustine Grass

St. Augustine, a warm-season grass, thrives in hot climates with seasides and can withstand periods of droughts better than other grass species. From southern Florida to the Gulf Coast states of Alabama, Mississippi, Louisiana and Texas as well as the occasional southern California lawn, St. Augustine grass tolerates some shade and most soils as well as salinity.


Follow the below best practices to keep your St. Augustine lawn healthy and strong:

Fertilization: St. Augustine grass requires a fertilizer that contains a high level of nitrogen, benefiting from a fertilizer with a 4-1-2 ratio of nitrogen, phosphorus and potassium. Fertilize your St. Augustine lawn when grass is actively growing in the spring to avoid late season frost, and don’t fertilize too late in the fall when the grass stops actively growing.

PRO TIP: St. Augustine grass in Florida can be fertilized all season long since it rarely goes dormant during the winter months due to warm temps.

Watering: Established lawns with St. Augustine grass should receive enough water from rainfall, since the species is drought-resistant. That said, a good rule of thumb is to water at the rate of 1” per week, all at once so water can reach the root system (we call this watering deep). Sandy soils may require more frequent watering (e.g. 1” every third day). In areas where the grass goes into dormancy in the cooler months (typically when the soil temp is below 55-F), watering should be reduced.

Mowing: St. Augustine grass should be maintained between 1” and 3” inches in height, depending on the amount of shade and how often you mow. Another factor to mowing height is which St. Augustine grass you have since the dwarf variety can withstand a lower height (2”). Never remove more than ⅓ of the total leaf blade during any one mow. Cutting too much off at one time will damage the grass. Heavy fertilized and/or watered grass will often produce thick thatches that may increase the frequency of mowing. During the growing season, you may find you need to mow weekly to maintain the recommended lawn height.

PRO TIP: In the fall, the mowing height should be about 1” taller than the summertime height since this longer length helps the grass accumulate enough energy to get through the cooler months.  

Pests: St. Augustine grass is susceptible to pests like chinch bugs and grub worms, which will eat the root system of your lawn. On the other hand, chinch bugs will suck your grass blades dry, killing patches or your entire lawn.

Indication of an infestation begins with circular yellow to brown patches in your lawn, using starting along the border or alongside sidewalks, that increase in size concentrically as the chinch bugs move from dying grass outwards. Though more active in the warm weather, these pests are problematic year round. The best way to determine if you have a chinch bug problem is to inspect your lawn border between dying brown grass and the green to scout for tiny, black and white chinch adults. Another good place to look is where two blades of grass come together at the base.

It’s best to deal with both kinds of pests immediately with all-natural and/or chemically aggressive treatments, such as:

  • Releasing beneficial insects such as ladybugs and lacewings into your lawn to feed on chinch bugs.
  • Spot treating with organic products, or dusting your lawn with organic diatomaceous earth, which is made up of fossilized aquatic organisms. Chinch bugs are damaged when they come in contact with the powder and will eventually die.
  • Treating damaged areas of your lawn with the least toxic pesticides you can find, although those that contain bifenthrin are unfortunately toxic to bees.
  • Turn to natural insect-repellent plants and herbs like thyme to help prevent bug infestation in the future.

Disease: St. Augustine grass is vulnerable to a variety of fungi like gray leaf spot that favors extended periods of humid or rainy weather. St. Augustine is also vulnerable to a species-specific virus known as St. Augustine Decline, or SAD, which does not respond to chemical control methods. Keeping your lawn healthy and strong, fed with nutrients that keep the soil and root system healthy, is the best defense against this or any other disease.

Weeds: St. Augustinegrass is sensitive to certain herbicides, so the use of these products to control weeds should be used with extreme caution and never when the lawn is under stress, such as if it’s been mowed too short or if you’re dealing with an extended period of heat stress. In early spring, you can look to control weeds such as crabgrass with pre-emergent herbicides.


Temperature, nutrients and moisture will influence the growth rate and appearance of your St. Augustine grass, but there are some things to be on the lookout for during the year.


// IN COOLER MONTHS (Spring/Fall)

Spring or early fall is also a great time to topdress a St. Augustine lawn.

In early spring, you can look to control weeds such as crabgrass with pre-emergent herbicides.

In the spring or during periods of heavy rainfall and humidity, your St. Augustine lawn may become more vulnerable to the virus known as St. Augustine Decline. Keeping your lawn fed nutrient-rich with a Sunday lawn care plan will help keep your lawn’s root system healthy and strong against disease.  

In the spring, you may want to plant insect-repellent thyme indoors in pots or in your garden. While this drought-resistant herb will not kill problematic bugs, it can help to repel them. And in fact, thyme oil can be used to make an all-natural insect spray.

In the fall when nighttime temps are cooler, the growth rate will slow but the increase in ground moisture will help your St. Augustine grass stay green. It’s only when temps fall consistently below 80-degrees F, or when soil temps are below 55-F, that your grass will go dormant and turn brown. At this time, the rate at which you water your lawn should be reduced and your mowing height should be 1” taller than the summertime height.

Pick a time in September or October to overseed your lawn. With St. Augustine grass, you may have to mow twice to achieve the optimal blade height since short grass helps St. Augustine seeds germinate.



During the hotter months of the year, chinch bugs and grub worms are most active, so keep an eye on the borders around your lawn where infestation usually begin.

Make sure you mow high and water deep during the hot summer months, when your lawn may undergo heat stress.  


A healthy St. Augustine lawn starts with soil. When your soil gets the nutrients it needs, it becomes the grass-growing powerhouse nature intended it to be and, at the same time, it becomes more resilient in the long run to weeds and disease.

Curious what makes Sunday’s nutrient blends so unique? Redeem your free lawn analysis today.