Garden View: How to use fertilizer during the fall season

Applying fertilizer in the fall has shown to really help plants with reemergence in the spring. Particularly with turf grasses, because of favorable environmental conditions nitrogen applied at this time aids the photosynthetic production of carbohydrates, which can be stored for later use. These reserves provide for an earlier spring green-up and an energy source for turf grasses to recuperate from drought and other related stresses.

However, plants will only uptake what they need and anything extra is wasted; do not assume that if you add a bit more, you will improve results. Additionally, over application of fertilizers can lead to excessive nutrients in our waterways, depleting oxygen and causing fish kills.

While fertilizing is so important for maintaining the ideal shade of green grass, excessive nitrogen can have negative effects. It can encourage soft, leafy green growth that will be more susceptible to frost and in general is less tolerant of heat, drought and mowing or wear stress. Too much nitrogen can also promote disease and weeds.

It’s so much easier to get good results when you know what you are working with, which is why I always recommend starting with a soil test. Unless you’ve done soil analysis in the last two to three years, how can you know what your soil and plants need?

Soil tests determine the amount of nutrients that are available in the soil for plant use and the soil pH (whether the soil is acid or alkaline), which can affect soil nutrient availability. Your soil test report will help you understand which nutrients your soil lacks and which are present in adequate amounts. The test results will include recommendations on the amounts of plant nutrients that would benefit your lawn.

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In our area, soil chemistry causes iron in the soil to be unavailable to plants leading to chlorosis or a yellowing of leaves while veins remain green. This has to be corrected with a foliar iron application.

While your landscape plants aren’t typically as needy as the lawn, it’s still a good idea to give them some love too. Ensuring your trees and shrubs are getting all the nutrients they need will help them be more resilient and vigorous, allowing them to weather storms and extreme temperatures. In general, the healthier they are, the more beautiful they look and the easier they are to care for.

Another option is to top-dress your turf and flower beds, with compost at a rate of one-fourth of an inch to half-an-inch over the desired area. Be sure to water it in enough to break down and get it into the soil.

An annual application of good, quality compost has the potential to improve soil quality, nutrient and water-holding capacity, and plant health.

You should not be able tell the origins of quality compost, it should completely broke down, dark and have an earthy aroma. If you see pieces of bark, limbs, etc. or it has a bad odor, look for another option.

Locally you want to get your fall fertilizer application done by Thanksgiving; leaving you plenty of time to get a soil test in first.

For a complete guide on “Lawn Fertilization for Texas Warm-Season Grasses” visit

Ashley Gregory is the Horticulturalist for Hidalgo County with Texas A& M AgriLife Extension Service. She can be reached at the Hidalgo County Extension Office at (956) 383-1026 or by email at