This is the time of year that I get a variety of questions about lawns, and the clock is running out.
The “clock” is the coming cooler weather and the first frost where your turfgrass will go dormant.
When should a homeowner do their last fertilization, should you seed/sod a new lawn now, and when do you quit watering your lawn?
You’ve got the rest of September to fertilize with a “winter-izer” fertilizer. It is a very beneficial practice but don’t do it too late. Generally, research recommends the absolute latest fall fertilizer application should be made at least six weeks before the location’s historic first-frost date. Our historic first frost is mid-November. So six week before that is October 1.
Fertilizing too late in the fall would be like someone preparing you supper just before bedtime! Your lawn is preparing for winter dormancy and a late feeding could be more disruptive than helpful.
Do add lime… if you need it. If you need to add lime to reduce acidic soils, add lime now to your lawns. Lime helps to neutralize the pH in our commonly low pH soils. Lime isn’t really a fertilizer although it does contain Calcium, a secondary nutrient for plants. Lime’s purpose is to provide a better environment for the plants to grow. One of its better attributes is that it allows nutrients to be more available.
Keep watering until all visible growth has stopped. I’ve had a number of folks ask if they should water during the winter months. It is true that your lawn and shrubs and other perennials need moisture year-round, but our climate typically provides enough moisture in our winter not to water. In the coming weeks (and certainly after our first frost) you can completely turn off your sprinkler system.
When to turn the irrigation system back on? April is naturally a good time. The grass will likely have started growing at that time and warm, drier weather would be starting.
If you are looking to start a new lawn, this is a tricky time. Certainly you can sod or seed now but cold weather is coming. The biggest concern is if the grasses become established before the winter shuts down active growth and establishment.
Watch and treat for diseases that are at their worst in the fall. Most fungal problems in lawns get their start in the spring, take a hiatus in the hot, dry summer and then really get roaring in the cool fall months. Interestingly, the most pampered yards are the ones that will have the most disease problems.
Too much pampering in the form of excessive watering and fertilizer may give you the greenest and lushest lawn in the neighborhood. Yet those excesses also sets up a lawn for the fungus problems.
Do treat for weeds in the fall to help stop the early spring weeds. You can (and should) treat for weeds each fall. Problematic warm season perennial weeds such as Spurge and Virginia Buttonweed can be killed now before they go dormant. Annual spring weeds such as Lawn Burweed and Henbit can be best controlled with preemergent herbicides as they are just trying to germinate.
Products may not be clearly marked as “preemergent” but may instead have language on them such as “weed preventer.” So, being familiar with some of the active ingredients can be helpful.
Common active ingredients used for preemergence control include prodiamine, dithiopyr, pendimethalin, isoxaben and others.
I have long recommended Atrazine. There are lots of products on the shelves at lots of stores that contain this active ingredient. It is very safe to use on our most common turf grass, St. Augustine.
So do these practices and set your turfgrass up to be one of the best in the neighborhood come next spring.
