In order to apply milky spore powder to your lawn, you must:
- Choose between milky spore powder or granules.
- Apply when the ground is not frozen, in spring, summer, or fall.
- Wear eye and airway protection when you spread milky spore.
- Fill your lawn applicator or spreading tool with milky spore.
- Apply milky spore evenly across the lawn.
- Water right after application to activate the milky spore.
- Repeat the application 1 to 2 times annually for 2 to 3 years.
Even if you’re not familiar with the tools or products required for spreading milky spore, you can tackle the job the right way on your first try. Then, you won’t have to worry about Japanese beetle larvae destroying your lawn.
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How Does Milky Spore Work?
Milky spore is a natural, organic product that kills Japanese beetle grubs. The P. popilliae bacteria in milky spore products enters the soil during application. Once the bacteria is in the soil it is ingested by the grubs as they feed on plant roots. Once the bacteria enters the grub’s system it infects them with milky spore disease, which kills the grub.
- Milky spore contains P. popilliae bacteria.
- This bacteria infects Japanese beetle grubs with a deadly disease.
- Milky spore is harmless to all organisms other than Japanese beetle grubs.
It is essential to keep in mind that milky spore products will only kill one life form of one species—Japanese beetle grubs. It is harmless to adult beetles and other types of white grub. This makes it safe, since it won’t harm people, pets, or any other organism. However, it limits effectiveness since milky spore won’t kill all types of harmful grubs.
7 Steps to Apply Milky Spore to Your Lawn
Following the right process to apply milky spore to your lawn will ensure you kill the most Japanese beetle grubs. Here is the best way to get the job done:
Choose Your Milky Spore Product
Before you begin the application process it is essential to pick your milky spore product. Milky spore is sold as a powder or granules. If you’re not sure which is right for you, read our guide comparing milky spore powder vs granules. Both products are effective.
- Choose between milky spore powder or granules.
- Milky spore powder is less expensive and requires fewer applications.
- Granulated milky spore can be applied with a lawn spreader.
Due to lower cost and fewer required applications, we prefer milky spore powder. However, the application process is similar for both. We will point out any differences between using milky spore powder and granules throughout this guide.
Apply at the Right Time
Milky spore powder can be applied any time the ground is not frozen. So, plan to apply between spring and fall. Early fall is the best time for application because Japanese beetle grubs feed aggressively just before winter sets in. So, applying it in the fall increases the chances that the grubs eat the bacteria in milky spore and are killed quickly.
- Do not apply while the ground is frozen or frosty.
- Milky spore is most effective when applied in early fall.
- Your application will still be effective in spring and summer.
- If possible, apply when daytime highs are 60–70℉ (16–21℃)
If you do not want to wait until fall to apply milky spore, make your application in spring or summer. Grubs will feed during these months as well, so the milky spore will be effective. If possible, wait for a cool period. Milky spore is most effective when temperatures are between 60 and 70℉ (16–21℃). So, treating your lawn while temperatures are still cool in spring can help kill off grubs before summer arrives.
Wear Protective Gear
Before you spread milky spore on your lawn, put on goggles and a dust mask. Milky spore is not dangerous to humans, but getting any sort of powder into your eyes and airways can be irritating. So, it’s best to gear up for the job.
- Wear eye protection and an N95 mask when spreading milky spore.
- Eye and mouth protection will prevent irritation from milky spore powder and granules.
- Don’t worry—milky spore is completely non-toxic to humans.
One of the big benefits of milky spore is that it is so safe to work with. Grub-killing pesticides carry far more risks than natural treatments like milky spore. You can take a look at our comparison of milky spore and GrubEx for more details.
Fill Your Lawn Applicator or Spreader
If you are using milky spore powder, fill a tube-shaped lawn applicator with the powder. Since the powder is very fine, it is best to do this in a wind-free area, such as inside your garage. This will prevent the powder from being blown away. Simply open the packaging and pour the powder into the open end of the lawn applicator.
- Pour milky spore powder into this inexpensive lawn applicator.
- Fill your applicator indoors to prevent wind from making a mess of the powder.
- Milky spore granules can be spread using a lawn spreader, like this one.
- Bags of milky spore granules will have specific directions for spreader settings.
A lawn spreader is the best choice for applying milky spore granules. You can use the same spreader you use for applying grass seed, fertilizer, and other lawn treatments. This way, you don’t have to purchase a new tool. Make sure the spreader is clean, dry, and unclogged. Then, fill it with milky spore granules.
Spread the Milky Spore on Your Lawn
Milky spore powder must be applied in a grid pattern with 4 feet (120 cm) between deposits. To do this, start at one edge of your lawn. Walking along the edge, tap the lawn applicator onto the lawn every 4 feet. This will release a small mound of milky spore powder onto the grass. Continue until you reach the far side of your lawn. Then, begin a new line 4 feet from the first and repeat the process. Keep doing this until there is a mound of milky spore every 4 feet on the grass. You may have to refill your lawn applicator several times.
- Apply milky spore powder by tapping the lawn applicator onto your lawn every 4 feet.
- Criss-cross your lawn until you have applied a small mound of milky spore in a grid pattern every 4 feet.
- For milky spore granules, set the spreader to a high-volume spread rate.
- Guide the lawn spreader back and forth over the lawn until the soil is evenly treated.
Spreading milky spore granules is even easier than using powder. Set the lawn spreader to a high volume, so the granules are spread thickly. Simply push the lawn spreader back and forth across your lawn to spread them. You don’t have to worry about keeping the granules out of gardens and flower beds, since they will help kill grubs there too.
Water Your Lawn
Water your lawn as soon as you are done spreading milky spore. Since grubs live belowground, it’s essential to pull the milky spore into the soil with water right away. This will activate the bacteria and bring it down to the level where grubs live. Then, the milky spore will start killing grubs right away.
- Water your lawn as soon as you’re done spreading milky spore.
- Water will pull milky spore into the soil where it can start killing grubs.
- Rain will also help activate milky spore.
If there is rain in the forecast for the next few hours, it is the perfect time to spread milky spore. You don’t have to worry about rainfall washing the product away. It’s far more likely that rain will help pull the milky spore into the soil so it can get to work.
Repeat Applications as Necessary
Milky spore begins working after the first application, but your lawn may benefit from repeated applications. Adding more milky spore will increase the population of grub-killing bacteria in your soil. You can apply milky spore up to 3 times per year (in spring, summer, and fall) for 2 to 3 years. However, one yearly application for 2 to 3 years is enough to get positive results.
- Apply milky spore up to 3 times yearly, with 2 to 3 months between applications.
- Continue to use milky spore for 2 to 3 years.
- After the treatment period, milky spore can continue killing grubs for up to 20 years with no additional applications.
Once you have established milky spore in your soil, it will often sustain its own bacterial population. After treating your lawn with milky spore for a few years, the bacteria can remain present for 10 to 20 years. This means a few milky spore applications can continue killing grubs for decades. So, it’s worth treating your lawn with milky spore a few times.
What is the Best Way to Use Milky Spore?
To use milky spore to kill Japanese beetle grubs, first purchase either milky spore powder or granules. Then, apply the product in spring, summer, or fall, when the ground is not frozen. Before you begin the application process, put on goggles and a dust mask. Then, fill your lawn spreader or applicator with the milky spore product of your choice. Apply milky spore powder in a grid pattern, with one small mound of powder every 4 feet. For granules, use a lawn spreader to evenly distribute the product on your lawn. Immediately after application, water your lawn to pull the milky spore into the soil. If desired, perform additional applications of milky spore to strengthen the grub-killing barrier in your yard.