Overseeding your lawn

Mon. Aug. 12, 2019

Click below to listen to my 2 min. Garden Bite radio show: Overseeding your lawn

While I advocate diversity in my yard, including the sweet smelling clover, there are plenty of people that want a lawn. So, for you folks, the best defense against weeds is a lush lawn.

Mid August to mid-September is the BEST time to overseed your lawn. The soil is warm, so seeds germinate quickly, The temps, in theory, should be starting to cool and getting perfect for growing grass.  Notice in the photo below the grass is dry in full sun, where there’s shade it’s green, well, greenER…

Here’s the how-to:

Cut the grass as short as possible.  It will act like a living mulch.  If the thatch layer, that brown dead stuff, is thicker than a half inch, remove it.  Use a vertical mower (you can rent one) and set the blades to cut the top half inch of soil.  This will remove the thatch while creating grooves or slits in the soil surface, making it a great seedbed.  Rake up the mess and compost the debris. There are various models of dethatchers.

Lawn thatch

You might also choose to core aerate your lawn.  Again, these machines can be rented.  The goal of a core aerator is to take plugs of soil out of your lawn to literally give it some oxygen!

Core aerator
core aerator soil chunks

Looks a little like something the family dog has left behind!  There are spike shoes too but they don’t pull out the soil like the aerator does – at that’s the point, to pull the chunks out and let them decompose back.


OVERSEEDING:  Spread grass seed over the renovated area using a broadcast or drop-type spreader.  Use 3 to 4 pounds per one thousand square feet of sunny grass-seed mixes or 4 to 5 pounds per thousand square feet of shady mixes.  Apply half the amount in one direction and the rest at right angles to the first.  Rake it in for good seed-to-soil contact.  The seed has to be touching soil to germinate.  Just tossing the seed over your grass is really a waste of time and money as odds are it won’t settle down far enough to make soil contact.   You could think of it as bird food.  My lawn is crispy right now and mostly weeds.  I suggest that you buy seed from a local nursery, tell them your sun/shade conditions.  Should you reseed, be sure to keep those seeds moist.  That may mean watering twice a day.  Check out this comprehensive guide to Lawn Renovation by the University of Minnesota Extension.  Lawn Care by the University of Wisconsin Extension.