Moss Control in Lawns

Updated: Nov 19, 2019

From October is the time of year where moss can start to flourish in some lawns if the cause is of this is not correctly dealt with. If the weather conditions for its growth are present, then some moss is expected which can soon be brought under control by regular lawn treatments.

If a lawn is rife with moss then there are underlying factors causing this that must be addressed. Read on for our thoughts on the best methods of prevention and control.

Why Moss?

Moss, with no root system, depends on surface moisture for it's existence. In a wet winter we can't eradicate this, but we can certainly halt it's progress. It will be more difficult to control in a shady, heavy clay lawn, over an open sandier soil. It can invade much easier where grass cover is poor, so the control of moss actually starts throughout the summer months, mowing and treating the lawn adequately - not dissimilar to the weeds.

With moss we look at both short term control and then long term prevention. If you're a customer of ours with a mossy lawn we'll be working with you to carry out some of these methods for the best lawn.

Method of Control 1 - Scarification

Scarification will remove moss via mechanical means. Scarification also attacks thatch, which is a possible cause of the moss growth. The thatch layer sits wet and moss can take hold.

Much is made of killing* moss before or after scarification. This can be achieved beforehand with a granular application of iron as the granules can make their way to the base of the plant and attack from bottom up. It is more effective to scarify first, removing the majority of the moss mechanically, before spraying with a liquid iron afterwards, finishing off the remaining moss growth, and inhibiting regrowth for a number of weeks following.

*Iron doesn't actually 'kill' moss, it dehydrates the moss plant. If the conditions exist which suits moss growth, then it will return to health. This is a reason why we do not scarify lawns November- January as much hard work can be undone by the weather. This is also why so many DIY products will scorch the grass also if it it applied at a too high a rate, at the wrong time of year, or without sufficient rainfall following - it is also dehydrating the grass. Even for lawn problems as simple as moss, chemicals are safer in the hands of a professional.

Lawn scarification in Nuneaton
A light scarification of a lawn in Nuneaton

Method of Prevention and Control 2 - Regular Lawn Treatments

Lawn treatments from ourselves or other companies are likely to contain iron if that be in granular or liquid form, which will give moss control. In our lawn treatments, this is the case for both our late-autumn and winter applications (Oct-Feb).

Not only is the moss control application important, but so is the nutrition being applied alongside this all year around. If the grass plants are strong then moss is less likely to form, certainly not with the same vengeance than with an untreated lawn.

Method of Prevention and Control 3 - Aeration

Aeration proves a list of benefits for your lawn and addressing moss is one of those. Within our lawn survey, we will often recommend a hollow-tine aeration for compacted lawns where surface drainage is poor - where we feel the removal of cores, a more aggressive aeration is the best way to go.

Within our maintenance package, we aerate with fracture-tines which provides deeper aeration into the soil for improved root depth and mass. If we can get water where it is needed most to the roots of the grass, rather than on the surface then moss will be greatly reduced.

Lawn aerators - lawn spiking
Our aerators - left with fracture-tines, right with hollow-tines

Method of Prevention and Control 4 - Good Lawn Mowing

Cutting your lawn at a sensible height and with a good frequency will reduce moss growth. Lawns were are cut short or mown infrequently will be placed under stress, and moss invade thin areas. If lawns are left too high then there will be a dampness present for moss to exploit. Maintain a mowing height of 20-40mm all year around dependent on the evenness of the lawn, removing no more than a third with any one cut. Do not forget about mowing during November and December months - keep the grass strong.

Method of Prevention and Control 5 - Reducing Shade / Improving Airflow

We've established that moss depends on moisture to develop and survive. If more air and natural light can get to your lawn then this is going to be of huge benefit. This isn't always possible in smaller gardens dependent on how the house is situated, but it can be limited.

September - December is the season for leaves to darken our lawns. Make sure they're cleared up as soon as possible so your lawn can benefit from the reducing natural light. Consider having trees topped / thinned if leaves are troublesome during autumn.

Specialist mechanical lawn care
Mechanical work completed in Lichfield, March 2019. Not much moss here!

Extreme Method of Prevention and Control 6 - Soil Exchange

Looking for a fine lawn? Drainage will be greatly improved in a sandier soil, rather than a clay soil. Clay soil compact easily and require more aeration. Sandier soils require more irrigation through summer, but will suffer less issues with water-logging through winter.

A move could be to hollow-tine out clay cores in several directions, scarify, over-seed, and top-dress with a lighter soil. if the upper reaches of your lawn can drain better, it's going to be far less inviting for moss. This will need to be repeated on an annual basis for several years as changing soil composition is a serious undertaking. The new material would need to be adequately worked in.