Q. I just recently mowed for the 1st time this year. The moss is so thick that it’s difficult to mow. It has not been thatched in years but we have used weed and feed with moss killer in the feed. This year is the worst ever. Will using dolomite lime help at this point? Or is it too early? Cricket Schackel – Graham, WA
A. So you haven’t thatched in years and you have been using weed and feed with moss killer. As Dr. Phil would say “How’s that workin’ for you?” Adding lime will influence the pH of the soil, which could influence the health of the lawn, if that is the problem here. The ideal pH of a lawn is between 6.5 (slightly acidic) to 7 (neutral) although lawns can grow well with pH down to 6.0. If you have been following my column you may recall that a few weeks ago I mentioned that this is also a good range to keep the soil because the soil microorganisms that break down thatch work best in this range. I also mentioned that excessive fertilization also promotes thatch. Moss in the lawn is a symptom and therefore solely treating the symptom is not a sustainable course of action. Moss overtaking a lawn is symptomatic of conditions that are not ideal for lawn growth (and therefore favor the moss). When the moss treatment is combined with the lawn’s fertilizer there is a good chance you will either over fertilizer to treat the moss. Hopefully you can see the vicious cycle that can occur. So first you need to test the soil’s pH and fertility and apply fertilizer and lime as needed. Then check to see how thick your thatch layer is by digging up a small section that can be replanted. More than ¾ inch layer means that you need to take corrective action. You should also check to see how the drainage and light levels are for the lawn. If the light levels are too low or water pools then you favor moss over grass. Correct these problems if necessary and then treat the moss separately and then you are on the way to a sustainable lawn.