September 2019 Lawn Diary

September 2021 Lawn Diary

This Month in a Nutshell

September, NOT October, is the prime month for autumn lawn renovation because there is warmth (usually), good rainfall (hopefully) and fewer seeding weeds (definately). It's good for toad stools and crane fly as well!

Summary 'to do' list for September:

  • Autumn Fertilising
  • Final Weed Control
  • Raking, scarifying and over-sowing
  • Aeration
  • Seeding

The Weather

From here on in things will eventually get cooler and wetter; exactly what is needed for renovation and seeding. Here is the next months outlook courtesy of the Met Office:

29th August to 7th September

High pressure is likely to dominate through the end of August and the start of September, resulting in fine and settled weather across the UK. This will bring variable amounts of cloud, sunny spells, a few light showers, and some fog patches overnight, which clear during early morning. It looks increasingly likely that largely settled conditions will persist through much of the rest of this period, though perhaps weak frontal systems bringing light rain and showers at times. Winds likely to be light to moderate for most, fresher along the east coasts, and breezier towards the far south, where it may feel cooler. It is likely to be rather warm in the west but cool in the east below any persistent cloud.

8th to 22nd September

Confidence is decreasing into this period, however there is a signal for high pressure and associated settled conditions to gradually become less dominant, with a trend towards more unsettled weather expected into the second week of September. This may bring changeable conditions with periods of showers and longer spells of rain, interspersed with drier spells at times, especially nearing the end of this period. Confidence is high that temperatures are likely to be near or above average for the time of the year.

Lawnsmith Shop Update

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If you wish to learn more then please go here.

Mowing the Lawn

If you have good levels of moisture around grass growth should be at or near its best so keep mowing weekly, though in Scotland lowering temperatures will soon start to slow growth. Once growth does start to slow, remember to raise your mowing height by one to two settings until spring next year. If cooler wet weather causes a resurgence of moss raise the mowing height even more so that at least 1/2" (preferably 1") of grass shows above the moss after grass cutting.


Now that the dew is returning try to mow in the afternoon. Damp grass can easily build up inside the mower so always give the mower a good brush, scrape or hose down after every use.

Fertilising the Lawn

September and October are great months for the Autumn lawn feed. Not only does this give you a fantastic lawn now, helping it recover from summer use but also 'winterizes' the lawn giving it some protection from the ravages of winter temperatures and disease. In addition, if your lawn has an abundance of moss or weeds it will be partly down to poor grass health with low nutrient levels being part of the problem.

If you've never tried an autumn feed on your lawn then do give it a go. The additional benefit it gives the lawn will keep it looking green and healthy through most of the colder months. This doesn't mean extra mowing over winter as temperatures generally stay below 80C meaning little growth but still good colour.

Our Autumn Fertiliser can be applied anytime from middle August through to November, though I'd consider no later than end October for Scotland. If your schedule puts you into a late October or November feeding then also consider using our Winter Green High Iron Fertiliser. This generates next to no growth, greens magnificently and the high iron content is great for moss control.

Spreading Fertiliser Videos Spraying Videos View Fertiliser Range

Weed Control

Most weed seeds will have germinated in your lawn by now so September should be considered as your last opportunity to clobber the weeds that remain. The most noticeable weeds at this time of year are cinquefoil, yarrow, thistles, hawks beard and hawkbit.

This is my preferred month for a full lawn treatment as you will get most weeds AND prevent them over wintering and thus being harder to kill in the spring. If needed apply weed killer to the whole lawn either by knapsack sprayer or watering can. If you're using a watering can try the sprinkle bar for faster more accurate application.

If you've been diligent with your weed control and only have a few weeds then keep at it with a combination of spot treating individual weeds with a Ready to Use Weed Killer or manually removing them.

See Weed Identification for more detail and control methods.

WARNING: Do not apply weed killer to dry or parched lawns other than as a spot treatment. Always read the label for advice on repeat treatments and safe use.

Watch the Video See Weed Killers See Sprayers

Moss Control

With the approach of wetter weather, moss will be making a comeback so consider cultural control methods, moss treatments with applications of a ferrous sulphate based moss killer or raking the moss out or a combination of all three.

Moss treatments with ferrous sulphate are very useful as a standalone procedure to control the progress of moss and can be used every 4 to 8 weeks throughout the cooler months to keep the moss in check. This way you may enter spring with no noticeable moss problem and avoid the job of raking it all out once again!

For those of you with concerns for safety of children and pets that are likely to be on the lawn soon after treating you can now use a chemical free product in your treatment program. See MossOff in the moss killer products link below.

Watch the Video Moss Killer Products

Watering the Lawn

This is unlikely unless you have little soil moisture and are planning lawn renovations such as scarifying, aeration or seeding. If you do water this month do it in the mornings to reduce the likelihood of disease.

Aeration & De-compaction

Autumn and in particular September and October is the time for hollow tining the lawn. If you're scarifying the lawn as well do it before tining. Other forms of aeration are perfectly acceptable but hollow tining is by far the best way to aerate at this time of year particularly if you aerate infrequently or have a moss problem. Hire a machine or visit our shop for a handy Hollow Tine Aerator.

If you are pottering about the lawn stick on a pair of aerator sandals and do two jobs at once. Getting as much air into the lawn, whether or not you have hollow tined, helps the grass after the summer and the extra drainage won't go amiss particularly if you have a moss problem.

Remember to fertilise the lawn AFTER aerating to produce deeper rooting.

Watch the Video See Aerators

Raking & Scarifying

As long as grass growth is good then the conditions should be excellent for raking or scarifying IF IT NEEDS DOING. Some lawns don't need much in the way of scarifying so check for thatch first.

If on the other hand conditions are dry then recovery after scarification may be compromised though scarifying whilst it's dry makes life easier. As nature usually provided adequate rain at this time of year all should be well but be prepared to get the sprinkler out if not.

If you're new to scarifying consider hiring or buying a petrol scarifier for large lawns or for smaller lawns an electric raker/scarifier or even the handy rolling lawn scarifier is ideal for lawns upto 200m2.

If you need to apply chemical weed control do it at least a month, preferably two months before scarifying. Don't apply any weed killer afterwards; wait until the following spring.

Finally, don't forget to fertilise and over seed your lawn after raking or scarifying. This is an often neglected part of the renovation process leading to slow recovery, patchy lawns and lots of weeds and weed grasses. So, use the Autumn Fertiliser or a pre-seeding fertiliser such as Lawnsmith® STARTER and finally over sow with new grass seed to make your lawns sparkle.

Watch the Video See the Scarifier

Repairs & Renovations

Renovation requires water to help grass seed germinate and to assist existing grass to repair and recover. Only undertake renovation if you can water if conditions are or become dry. Any turfing laid will require regular watering to establish.

Traditionally October heralds the start of the turfing season as there is plenty of moisture and little dry weather enabling the turf to root without the need for watering.

Pests & Diseases

If you've had red thread in the lawn this year it should now be coming to an end as the cooler weather creeps in. In addition, your autumn lawn feed will help grow it out so by the end of September all signs should be gone.

If your lawn suffers from 'dry patch' or 'fairy rings' then these areas may become more evident this month as the grass in none problem areas starts to benefit from the rain. If they are obvious then watering, spiking, fertiliser and a wetting agent such as Yucca will go a long way to relieving the problem.

Yellow meadow ants - If you find any ant activity in the lawn (normal as the young queens have recently left the parent nest) you are best off dosing the nest with Ant-Stop in granular or liquid form before they go dormant for the winter. This prevents the massive ant mounds in the following spring and summer which can cause considerable grass damage and mowing problems.

Worms: Though it's best to treat for worms at the first sign, they will continue to surface throughout the winter and produce muddy casts that cause mowing problems in the spring. Worms are beneficial in that they digest organic matter providing nutrients and enriching the soil. They also do some valuable aeration. A lawn with worms is generally far healthier than one without. Though only moderately reliable we still feel Ferrous Sulphate is the most cost effective way to reduce worm casting.

Finally, toadstools may start appearing which generally should not be of concern but more importantly you may have started seeing Crane Fly (Daddy Longlegs) in the garden and the house. If you see a lot flying about the lawn have a read of Crane Fly & Leather Jackets though unfortunately there is no reliable treatment should you have an infestation of leather jackets.

View Yucca Wetta View Pest & Disease Products

Rolling the lawn

Unlikely to be required until next spring unless you've over sowed with grass seed.

Top Dressing

Top dressing is an advanced lawn care procedure to reduce thatch and smooth the lawn surface. If you are not a lawn nut then I suggest you don't need to bother!

If you are and growth is good, then you should be considering applications from August into October. Combine topdressing with any other lawn renovation procedure you may wish to undertake. See top dressing advice.

The New Lawn

With the potential for wetter weeks you should be seeding prepared ground for your new lawn. Be prepared to water if the weather turns dry. The seed needs to be in by mid month for Scotland and end of September for everyone else otherwise it may not have the warmth to germinate.

View Grass Seed Blends

*Lawnsmith product categories from this diary:

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Have a great month