Algae and Moss in lawns

Algae and Moss in lawns can develop with the following preconditions:

1. Area is fully shaded receiving only referred light
2. North facing areas fully shaded by trees or fence
3. Soil profile is permanently saturated from an underground soak
4. Soil profile is substantially ‘lower’ then surrounding profile.
5. Soil is compacted and with poor drainage
6. Winter cool wet ambient conditions
7. Poor soil aeration (anaerobic microbial conditions)
8. OVERWATERING from auto irrigation

Overwhelmingly, the cause of rampant algae and moss in lawns in Melbourne’s southeast is OVERWATERING. Invariably, the householder has not dialed back the lawns watering requirement on the auto irrigation controller. For the winter months the auto irrigation controller should be off, perhaps with a manual watering once in a while.

To put it perspective, the evapotranspiration rate in winter is one–sixth of that in summer, turfgrass is in the low ebb of growth and we are generally inundated with showers through winter. Considering these factors, you need to manage against growing Algae and Moss in lawns.

To get rid of Algae and Moss in lawns, here’s what to do:

1. Change your management practice to remove the preconditions above. Turn your irrigation controller off for winter.
2. Rake out the moss vigorously, north-south, then east-west
3. Apply iron sulphate, either granular or in solution.
4. Repeat weeks later as necessary

The moss should turn black and shrivel up.

Note: Iron sulphate will stain concrete and tiles. Clean up with a blower vac or hose following application.