Garden Plot: Lawnapalooza, seeding and grub control

WASHINGTON — Meet Mike in Warrenton, Virginia, at 1 p.m., Sept. 5.

Mike will get you right back in the garden when he extols the joys of “The Second Season: Garlic, Pansies, Salad Greens and More” in a free talk at the Lee Highway Nursery, at 7159 Burke Lane.

Yes, it’s time to sow fresh seed

Richard in Silver Spring writes: “I’m spreading Maryland’s Leafgro compost over my backyard this weekend as part of a plan to reseed my ‘not much of a lawn’. The soil tested acidic, so I spread lime last weekend. Is it too early to start seeding this weekend?”

Not at all Richard; in fact, your timing is pretty close to exquisite.

Cool-season grass seed (fescue, bluegrass and rye) sown in the spring generally flops, because the soil is too cold for good germination. Then, summer swelter wipes out any of the heat-intolerant grass that managed to sprout.

But the soil is perfectly warm now, ensuring virtually instant germination. With the worst of the summer heat behind us, a cool-season grass such as fescue or bluegrass will grow healthy and strong over the coming months. That grass will be almost a year old before it has to endure its first full summer.

Combined with the naturally rich seedbed of that fine local compost, you have your best possible chance at a bulletproof lawn. Nice work!

Bagged grass clippings + D.C. heat = Yuck

Kim in D.C. writes: “I provide the gentleman who cuts my grass with compostable lawn/leaf bags for the clippings, and he puts the bags in our trash can for pickup.

“But I travel quite a bit in summer and sometimes miss our weekly trash pick-up. Then I come home to a soaking wet and moldy mess in the trash can. (The D.C. heat combines with the water content of the grass clippings to make a powerful mess!)

“I’m trying to do the right thing by cutting down on my family’s use of plastic and promoting the composting of grass clippings. What can I do?”

Well, the easy answer is to not put the bags into a can. Although large amounts of clippings alone are always going to be prone to getting moldy and messy, they’ll have a much longer non-stinky life out in the open, where the bag can “breathe.”

Most people sit these kinds of green waste bags out by the curb to begin with; unlike bags containing kitchen garbage and other food waste, vermin aren’t going to be interested in leaves or grass clippings.

You could also ask your lawn man to take the bags with him when he’s done.

But the real answer is to not collect the clippings

Grass clippings are 10 percent nitrogen by weight; that’s the perfect level of the perfect food for healthy lawns. Removing the clippings after mowing literally starves the lawn of a great whole-food meal; returning the clippings to the turf provides a natural slow-release feeding every time you mow. And, it’s the only legal ‘extra feeding’ you can give lawns in Maryland and Virginia, where new laws heavily restrict the amount of bagged fertilizer you can apply.

True mulching mowers, which have a sealed deck and no way to bag, pulverize the clippings to a fine powder that drops back to the lawn almost invisibly. You won’t see any clippings left behind; the sealed deck and super-sharp blade of a mulching mower reduce them to a fine powder.

Older mowers can be easily converted into mulchers; contact the manufacturer or your local dealer for a conversion kit—a plug to stop the grass from exiting the deck and a specially designed blade that reduces the clippings to that fine powder.

Oh, a final note: Do not compost your clippings or offer them up for community composting if your lawn is treated with herbicides. Some modern herbicides are so persistent that they can continue to kill non-grass plants even after becoming compost. The only safe place for those clippings is on the lawn they came from.

Are beetle grubs chowing down on the roots of your lawn?

Ray in Manassas writes: “Have I missed the window to apply milky spore powder to my lawn?  In the past, you have said that the best time to infect large numbers of beetle grubs is in late summer, when the grubs are up high in the lawn and actively feeding. I had a huge population of Japanese beetles this year. They have dissipated now, but I suspect the females have laid lots of eggs.”

Ray, this is the perfect time to apply milky spore powder. This naturally occurring soil organism only works when big grubs are feeding on the roots of your lawn in warm weather — which is now. Grubs don’t feed in the spring, and spring soil is too cold for the milky spore to work then anyway.

But applied now, the milky spore will be quickly ingested by the beetle grubs that are almost certainly chewing on the roots of your lawn. The milky spore will quickly eliminate the grubs without harming anything else in the environment.

It has no effect on people, pets, earthworms, etc. It only kills grubs that are eating the roots of your grass. Just one example of how organic pest controls are so much cooler than toxic chemicals!

And now, a new way to beat the beetle grubs

This just in: A brand new alternative to milky spore is a product called Grub Halt, which is only available from the mail-order supplier Gardens Alive. They have an exclusive on it for this season. It’s a new strain of the natural insecticide that, like milky spore, only targets beetle grubs that are actively feeding on the roots of your lawn. It’s performed very well in research studies, and this is the very first year it’s available to the public.

Bt is short for Bacillus thuringensis, the name science has given to a family of soil-dwelling organisms. Farmers are very familiar with the first Bt to be released, BTK. Some of the farmers who have relied on it for decades may not realize it, but the brand-name products such as Dipel and Thuracide they spray on crops under attack are non-toxic to any other form of life. BTK only kills caterpillars, and it only kills caterpillars that eat the sprayed leaves.

Another strain of Bt, known as BTI, is the active ingredient in those mosquito dunks and granules you toss into standing water to prevent mosquitoes from breeding.

This new strain is BTG (‘G’ for ‘galleriae’). Just made available to the public, it is effective against both the adult and larval forms of Japanese beetles and other members of the plant-munching scarab beetle family.

One formulation is designed to be sprayed on plants under beetle attack (Gardens Alive calls it Beetle Jus). The Grub Halt formulation is meant to be watered into lawns to kill beetle grubs feeding on the roots of the grass.

Final note: It would be counterproductive to apply both milky spore and Grub Halt to your lawn in the same season: not dangerous in any way, but just a waste of money. They may not work as well together as one alone. So choose one, and if the results aren’t satisfactory, switch to the other next summer.

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