Several factors go into maintaining a healthy lawn. Mowing it with a sharp blade makes a clean cut and helps prevent the lawn from being exposed to disease. Water and sunlight help the lawn grow, and adding fertiliser provides food for the lawn. Potassium, or potash, is one of the ingredients used in lawn fertiliser. It helps other nutrients flow through the plant, and protects it against heat, cold, insects and disease. Potassium is found in standard fertilisers, but you can also get organic potash from sources such as hardwood ashes and granite dust.
Measure the area of your lawn to determine how much potash you need to add. Depending on the shape of your yard, it might be easiest to break the yard down into sections, multiply the length and width of each section, and add the areas of all the sections together. If you are using actual wood ash, Julie Day of DannyLipford.com recommends using a 5-gallon bucket of potash for every 1,000 square feet of your yard. If using a store-bought potash fertiliser, follow manufacturer instructions for the amount to use.
Calibrate your spreader. Pour the amount of potash you need for 100 square feet into the spreader. Apply it to a hard, clean surface that measures 100 square feet. If you have potash left in the spreader when you're finished, you need to release it at a faster rate; if you run out of potash before you reach 100 square feet, you need to release it at a slower rate. Sweep up the potash and put it back into the spreader.
Spread the potash onto the lawn with the spreader. Begin spreading the potash around the perimeter of the lawn, and go back-and-forth over the lawn in rows that slightly overlap each other. Walk at a steady pace, and close the door on the spreader when you reach the end of the row. Turn the spreader around, and open the door once you start moving again. This prevents the potash from burning the lawn. Continue until the lawn is complete.
Water the lawn the day after you apply the potash to wash it off the blades of grass and into the soil.
Wash out the spreader after you apply the potash as it is corrosive and can eat away at the spreader.