Fertilizing in the Summer


Sarasota County is one of many counties in Southwest Florida that have established restrictions on the application of Nitrogen and Phosphorus fertilizer. Sarasota County’s fertilizer blackout prohibits the use of Nitrogen and Phosphorous fertilizer applied to turfgrass and landscape plants from June 1st through September 30th.  However; the application of Potassium, Magnesium, and micronutrients such as Iron and Manganese, is not restricted.

Potassium is an essential macronutrient and is the third number in the large list of three numbers on the front of a fertilizer bag. The first number is Nitrogen and the second number is Phosphorous. Potassium acts as a “vitamin” for turfgrass and landscape plants and also increases plant and root strength and cold hardiness.  Magnesium, also a macronutrient, is essential for the production of chlorophyll, essential to photosynthesis, and also plays a part in the movement of carbohydrates from leaves to other parts of the plant.

Micronutrients are elements that are only needed by plants in small quantities but still play important roles in plant functions.  Iron is involved in the production of chlorophyll and is required for certain protein functions.  Manganese plays a role in photosynthesis and the formation of chlorophyll.

Turfgrass often displays a yellow color during the mid-summer rainy seasons due to the heavy rains flushing Nitrogen away from plant roots. If your lawn is looking sad and yellow a little Iron can often give a temporary green-up.  Iron is not a replacement for Nitrogen but can work well during our summer rainy season.  Applications of chelated (Iron added) micronutrients will also do the trick.

Palms require specialized fertilization because Potassium deficiency is often an issue during the summer.  Applications of 0-0-16-5Mg +micronutrients fertilizer will help to reverse the problem.  Always remember that palms require 1/3 as much Magnesium as Potassium to prevent a human-caused deficiency due to an imbalance of these nutrients.  Potassium and Magnesium, both being easily dissolved by water, should always be applied in slow-release form.  Once the summer blackout is over, applications of 8-2-12-4Mg+micronutrients should be applied on a regular basis.

For further information, please see the following website:  https://www.scgov.net/WaterServices/Pages/FertilizerManagement.aspx

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