October the best time to fertilize your lawn

By Michael Potter / Horticulture columnist

October is an important month for your lawn. A weak turf is much more susceptible to winter damage and other stresses. In addition, turf is much slower to recover in the spring. Early to mid-October is the best time to fertilize due to cooler weather that causes grass growth to slow down. Slower turf growth rates combined with slow release fertilizers give good results for a wonderful spring green-up. There are a few things to consider for fall lawn care.

I would suggest using a fertilizer that is high in nitrogen, low in phosphorus and has a moderate to high level of potassium that such as a 15-5-10, 21-7-14, 18-6-12 or something similar. You should try to find a fertilizer with at least of the nitrogen in a slow release form. If you have had recent or continuous issues with Take-All Patch or Large Patch (Brown Patch), then you should consider using more natural type fertilizers with lower nitrogen rates that release slowly. Just dont go overboard with the nitrogen. Research shows that high nitrogen in a fast-release form can increase the activity of fungus. Slow release forms provide the lawn with nitrogen over a longer period of time resulting in a consistent growth while reducing nitrogen run off. Be sure to check the recommended rate of application on the label and take a few minutes to measure your yard. This will help you to apply the right amount of fertilizer for the area. Most people discover that they have better results using too little fertilizer rather than too much. Too much can lead to additional problems. Lastly, if you have not performed a soil test, now would be a good time to do one. You can either pick up the kit from the Texas A&M AgriLife Extension office or download the instructions and form at http://soiltesting.tamu.edu/. A soil test will let you know how much fertilizer to apply and more specifically what nutrients are needed for optimum growth.

Most annual winter grasses and weeds that plague lawns in late winter and early spring begin to germinate in September and October. The best way to stop them in the lawn is to apply a pre-emergence herbicide before the weed seeds start to germinate. Now is a good time to work on this problem as well. Pre-emergent herbicides are chemicals that kill weed seedlings as they germinate. They are not effective once weeds grow beyond the seedling stage. They should be applied according to the label in a uniform broadcast treatment, followed by at least 1/2 inch of rain or irrigation to move the product down to the soil where it is activated.

Post-emergence herbicides are used for weeds which have already begun to show up. You have to be careful with these because most of them can damage St. Augustine grass if temperatures are in the mid to upper 80's. There is a "window" of time in the fall to catch the broadleaf winter weeds. The earlier you catch them the better. Just watch out for days which are too warm. Also be careful not to get them on desirable flowers, shrubs, etc. They don't know the difference between a broadleaf weed and a broadleaf ornamental!

Over-seeding is generally not recommended on St. Augustine lawns. It competes with the grass for sunlight, nutrients and water. The additional competition from over-seeding slows spring recovery of the turf. If your turf is stressed or weak already, I would avoid over-seeding altogether. It will only make the problem worse.

Just remember to reduce your watering as temperatures start to cool off over the next few months. Turf will not need the typical 1 per week watering. Excessive water will only be wasted. Reducing or turning off irrigation will not only save water but will reduce your water bill.

Dont forget to send your garden questions to Plant Answers at 9020 Airport Rd., Conroe TX 77303 or e-mail: mpotter@ag.tamu.edu.

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October the best time to fertilize your lawn