If you live in the NW, specifically in the Portland area chances are you have acidic soil. Acidic soil is a measurement of the PH of the soil. Ideal PH for lawns is between 6-7, with 7 being neutral. A PH level below 6.0 indicates acidic soil and causes important nutrients to become bound up in the soil making them unavailable to the grass. As a result your lawn will slowly die. You’ll notice a loss in color, reduced growth and the appearance of different mosses growing into the dead areas of grass. Moss loves an acidic soil and our moist, temperate conditions with consistent rains are the perfect home for invading mosses.
Applying lime helps to balance the PH level in the soil. First a soil sample should be taken to determine the PH. This will help you know how much lime to apply and how many times it will need to be applied. To do this soil samples, preferably 3-5 from different areas of the lawn, can be brought to a government or independent soil testing facility for the most complete results. An at home self-test kit or PH probe can also be used. These can be purchased at most garden centers or anywhere that sells gardening plants and supplies. Again it is preferred that several areas of the lawn be tested to help get a full profile of how the lawns soil is behaving.
Once it’s determined that the soil is acidic it’s time to apply the lime. Lime comes in a powdered form and pellet form. Both are useful in increasing the soils PH. The powdered form can be a bit messy to apply but will work just as effectively as pellet form. Once you’ve purchased the lime, simply fill your spreader and set it to apply the lime at the appropriate rate as indicated in the instruction manual for your spreader on the package of lime. Simply walk back and forth spreading the lime in horizontal rows until the entire area is covered.
Generally the rule of thumb is the 100 pounds of lime spread over 1,000 square feet will raise the soil PH level by 1 point. An application of more than that is not recommended. If your soils PH test indicates that it needs to be raised more than one point than several applications may be needed, preferably at least a month apart, with continual testing with a probe. Aeration of the lawn in recommended prior to applying the lime as this helps the lime contact the soil more thoroughly.
Both Fall and spring are good times to apply lime to your lawn, however, wait for a dry day to administer the lime. Moist grass encourages the lime to stick to the blades and not getting into the soil where it’s needed. After application water the lime in for further penetration into the soil. When putting in a new lawn an application of lime to the topsoil is a very good practice in our area, simple follow the instructions above and then repeat as needed every 3 to 5 years. And most importantly enjoy your lawn!