Reasons For Over Seeding Lawns

Often when growing Warm Season Grasses, it can be noticed that some areas of the lawn can die back when Winter arrives. To overcome the detrimental appearance and reduced functionality of the lawn during the colder months, a Cool Season Grass can be planted in it's place for the duration of the Winter. If necessary, this practice may need to included in the lawn care for some homeowners each year.

Why Lawn Die Back In Winter

All lawns require varying levels of direct sunlight each day in order to both stay alive and stay healthy. Another requirement, and more so for Warm Season Grasses, is their need for warmth. The warmer the temperature, the more active they become, and vice versa, the colder the temperature, the more the lawn enters into a state of dormancy.

The last factor is the position of the sun in the sky. In Winter, the sun moves more to the North, creating greater areas in the garden that may receive no direct sunlight at all during the Winter.

As temperatures drop and sunlight lessens, and as the sun changes position in the sky, the most vulnerable areas of our lawns begin to reveal themselves. The lawn becomes thin, the thatch layer deteriorates, moss can grow, and areas of the lawn can even die off.

Why Over Seed Lawns

The same lawn areas that are hostile to a Warm Season Grass, may in fact be friendly to a Cool Season Grass. In knowing that lawns may die off in areas in Winter, we can instead sow a Cool Season Grass to grow in it's place for the duration of Winter.

As the weather cools the Warm Season Grass dies off, allowing for the establishment of the Cool Season Grass, which occupies this position throughout the Winter. Keeping our lawns looking green and lush, when otherwise they may have died off, risking permanent damage from any wear, and ruining the appearance of our lawns over this time period.

As the weather warms as Spring again approaches, the Cool Season Grass will die off, allowing for the re-establishment of the original Warm Season Grass.

How To Over Seed Lawns

First we must remember that Cool Season Grasses have no runners, so it will not spread. With this in mind, seed should be spread in enough quantity to cover the affected area sufficiently. This is no time to scrimp and save, if under-seeded, the results will look rather unappealing. So if it's worth doing, it's worth doing well right now.

Only ever over-seed the areas known to be susceptible to die back during Winter. Over-seeding otherwise healthy lawns that may be semi-dormant in Winter, with a Cool Season Grass, will only ever make for a very messy lawn, full of sporadic uneven long grass stems shooting out from the turf. Not a good look.

When To Over Seed Lawns

If you are aware from previous seasons, that certain parts of your lawn will die back during Winter, then planning for this event is the best solution. If you can see a problem beginning to develop during Autumn, then remedial action should still be taken quickly.

Over-seeding should begin in mid Autumn to allow enough time for the new seed to germinate and establish, before the coldest months set in.

Considerations When Overseeding Lawns

Often a growth and varietal difference can be noticed between your normal Warm Season Lawn, and the over seeding you just did with a Cool Season Lawn after Winter has set in. If left a month between cutting, your regular lawn will have grown little, while the new variety may have grown 50 - 100 mm.

This is more than a reasonable trade off for many to keep their lawn green over the Winter, but annoying for others, who may prefer the dead patch. Any uneven growth is evened out after mowing, and a reduced mowing frequency may even be an option to consider. Overall, the benefits definitely outweigh any perceived difference in the varieties as seen by some.

The final consideration, is when your lawn is mown with a Cylinder Mower. These mowers are often set to cut at around, 12-25 mm, which is fine for your regular lawn. But for the over-seeded Cool Season Grass, it is not good, because mowing at these low heights will kill the new grass. The minimum height for mowing Cool Season Grasses is 40 mm.

The solution is to cut the entire original lawn as normal with the Cylinder Mower. Then depending on the size of the over seeded area, it should either be cut with a Whipper Snipper, or a Rotary Mower if the area is large enough.

For lawns which are normally mown with a Rotary Mower, there is no difference in cutting, unless a slight height adjustment may be required between the two to maintain proper lawn care and lawn health.