The end of the growing season is upon us here in the Charleston area, and that means it’s time for us to apply potash to our lawns to strengthen them for the upcoming dormant season.
Unlike winterizer blends sold by big box stores, pure sulfate of potash sold at local nurseries raises potassium levels in soil without raising levels of nitrogen or phosphorus, the first two numbers displayed on bags of lawn fertilizer. Adding just potassium is important for two reasons: 1) Nitrogen promotes new above-ground growth, which, this time of year, increases the probability of grass being damaged by weather and/or traffic during dormancy; 2) Located near the ocean, most soil in the Lowcountry is naturally high in phosphorus.
The third fertilizer bag number, potassium, is the only one you should increase this time of year. Potash is, by definition, a soluble form of potassium.
It’s important to apply potash before grass goes dormant. Although the abnormally warm and wet El Niño weather we’ve been having this fall may extend this year’s growing season, grass in the Charleston area typically goes dormant during the second half of November. So, make sure to apply potash in the next couple of weeks, if you haven’t already.
Seth Mason, Charleston SC