The best time to renovate a lawn is after the heat breaks in August and September, according to Homegrown NH Host Emma Erler, lead horticulturist at Kirkwood Gardens. That’s because weed seeds do not germinate as readily, and grass seeds do well in cool fall weather.
Erler says grass should be planted until early October to get it established before the ground freezes.
Renovation steps to take
“The best thing you can do right off the bat is get your soil tested,” says Erler. “That's going to give you a lot of information on what your soil might be lacking.”
If your soil test tells you that you need to make a pH correction to your lawn, fall is the ideal time to do so. “The majority of us are going to benefit from the application of lime,” says Erler. “It takes lime months to really change the soil.”
Erler says much of the soil in New Hampshire yards and gardens tends to be very sandy and coarsely-drained, meaning it does not remain moist. Cool season grasses prefer to be well-watered, so Erler suggests adding organic matter like compost.
If you plan to totally redo your lawn, Erler recommends roto-tilling in 3 to 4 inches of compost to increase the organic matter.
If your existing lawn just needs a bit of rehab, top-dress with a quarter-inch of compost. Just rake it thinly over the top.
“That's going to help improve the moisture holding capacity of the soil,” says Erler. “It's also going to add nutrients.”
If you have compacted soil, Erler recommends using a hand tool or a core aerator before seeding.
Which grass seed to choose?
It's important to choose the right grass species for your lawn, and Erler says three main cool-season grass species make it into mixes.
“Kentucky bluegrass is probably what most of us in New Hampshire are thinking of when we think of lush, thick lawn,” she says. “You also have fine fescues and perennial rye.”
There are different benefits to each type of grass, and Erler recommends a mix of all three.
Spread the seed uniformly by applying it in two directions perpendicular to each other. Seeding rate varies, but Erler says most seed mixes fall in the range of 3 to 6 pounds per 1,000 square feet.
Initially, in order for seeds to germinate, the seed must be kept consistently moist and lightly watered. In the early stages, 10 or 15 minutes at a time with the sprinkler is enough.
“Once the grass germinates and develops roots,” Erler says, “it's going to be more important to water thoroughly and deeply.”
Alternatives to grass seed
Adding white clover to lawns is something that Erler has seen gain traction in the last decade, and specifically micro-clover, a specially-bred dwarf cultivar which has a small, finer-textured leaf.
“The real benefit to clover is that because it's a legume, it fixes its own nitrogen, so essentially it is making its own fertilizer,” says Erler. “And when you mow, those clippings from the clover are going to further fertilize the grass species that you have in your lawn.”
White Dutch clover is not native, but it does have a number of benefits to wildlife. “And bees absolutely love it,” Erler says. “So if you don't mind having bees in your lawn, then white clover is a really wonderful addition.”
“It's the best ground cover you can have for heavy traffic areas,” says Erler. “There's really nothing better for pets or kids.”
See you in the garden!
If you have a gardening question for Homegrown NH, email or send a voice memo to HomegrownNH@NHPR.org.
Homegrown New Hampshire is a collaboration between Squam Lakes Natural Science Center and NHPR.
