Plants use sunlight, water, and carbon dioxide (CO₂) to make food through photosynthesis. In fall and winter, less sunlight, cooler temperatures, and less rain cause photosynthesis and growth to slow down. Because of this, plants need very little nutrients and water during the cooler months.
In Central Florida’s fall and winter climate, plant growth slows or stops in winter. Deciduous trees drop their leaves and turfgrasses often turn yellowish or slightly brown. It’s normal for grass to lose some of its green color in winter. During the fall, plants move carbohydrates and nutrients from their leaves down to the roots. This is what causes tree leaves and grass blades to change in color. The roots use these stored resources to sustain the plant until spring when warmer temperatures and more sunlight signal that it’s time to grow again.
Keeping grass deep green during cold weather can stress the lawn and cause damage. Trying to force grass to grow when it naturally wants to rest leads to weak growth, increases disease risk, and delays spring green-up. Make the last fertilizer application right after the summer fertilizer ban ends in October, but no later than mid-November. This helps grass store food in the stems and roots, giving it energy to stay healthy through winter and grow back stronger in spring.
Because plant growth slows in winter, they need much less water. Adjust your irrigation system to run no more than once every 7–14 days if there’s no rain and turn it off when it does rain. Overwatering and fertilizing during the winter wastes water and fertilizer, and can cause fertilizer nutrients to wash into lakes, rivers, and the bay. Watch this short video to learn how to adjust a common irrigation controller.
Fertilizer Guidelines
- Use slow-release, balanced fertilizers with a 1:1 or 2:1 ratio of nitrogen (N) to potassium (K), such as 15-0-15, 16-0-8, or 24-0-11. The 1st number is nitrogen, the 2nd is phosphorous and the 3rd is potassium.
- Avoid phosphorus (P) unless a soil test shows it’s needed.
- Last fertilizer application: November
- First spring application: Late March or early April, after the grass begins to green up naturally.
- Apply no more than 1 pound of nitrogen per 1,000 sq. ft. per application and no more than 4 pounds of nitrogen per year. So, how much fertilizer is that?
- For example: Using a 15-0-15 fertilizer, divide 100 by the nitrogen number on the bag, 100 ÷ 15 = 6.7. This means 6.7 lbs. of the 15-0-15 fertilizer is needed for every 1000 sq. ft. of lawn to deliver one lb. of nitrogen (about one-third of a 20-lb bag).
- Skip “winterizer” products — many products are high in nitrogen and lead to nutrient runoff.
- Ornamental plants often get enough nutrients from nearby turf areas; only fertilize if a deficiency is identified.
Irrigation Guidelines
- During cooler months, reduce irrigation:
- Set your irrigation controller to run every 7-14 days or 50% of the normal schedule, or
- Turn the system off and water manually only if there’s been no rain for 10 or more days.
- Don’t irrigate during a freeze. Water plants before freezing weather instead.
- Avoid scalping (cutting grass too short); scalping can damage turf and slow spring recovery.
- For brown patches, schedule an irrigation audit and verify a pest or disease before treating with any pesticide. Environmental stress and misapplication of fertilizer or herbicides can be mistaken for a disease or insect issue.
For more information contact Susan at UF/IFAS Extension Hillsborough County at 813-744-5519 Ext. 54103 or szcrmchz@ufl.edu.
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Go to the ProHort website: https://sfyl.ifas.ufl.edu/hillsborough/professional-horticulture/
An Equal Opportunity Institution. UF/IFAS Extension, University of Florida, Institute of Food and Agricultural Sciences, Andra Johnson, Dean.
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