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How to apply beneficial nematodes

Step-by-step directions for applying BioLogic nematodes with a watering can, a Nema-Jet or hose-end sprayer, or a pump or backpack sprayer, and by hand as a topdressing, plus which garden chemicals are safe to use with them.

Beneficial nematodes are living, microscopic worms, so how you apply them matters as much as which ones you buy. Questions? Contact us.

The basics

  • Keep cold, never freeze

    Refrigerate it as soon as it arrives (35–50°F) and use it by the date on the package.

  • Coarse spray, not a mist

    Keep the mixture moving so the nematodes don't settle.

  • Don't let it dry out

    In hot, dry weather, water the area now and then for the first couple of weeks.

Follow these, and nematodes work well even in hot, dry summer weather.

Sprays: Scanmask, Ecomask, and Heteromask

For Scanmask, Ecomask, and Heteromask.

  1. Apply in the evening

    Out of direct sunlight.

  2. Water first

    Water the area to be treated.

  3. Mix, wait 20 minutes, mix again

    Mix thoroughly with clean, cold water. Let it sit for 20 minutes, then mix again right before you apply.

  4. Water after

    Washes the nematodes off the leaves and into the soil.

  • Watering can

    4 gallonsof water per 5 million
    1 gallon per 50 sq ft

  • Nema-Jet or hose-end sprayer

    ⅓ cupof water per 5 million
    1 cup per 600 sq ft

    Set the sprayer to ON (or its highest dilution setting).

  • Pump or backpack sprayer

    1 gallonof water per 5 million
    1 gallon per 200 sq ft

    Remove any filters 50 mesh or finer.

5 million nematodes is about 1 packed teaspoon.

How much water to mix, by size:

Size Nema-Jet or hose-end Pump or backpack Watering can
5 million ⅓ cup 1 gallon 4 gallons
10 million ⅔ cup 2 gallons 8 gallons
25 million 1⅔ cups 5 gallons use a sprayer
50 million 3⅓ cups 10 gallons use a sprayer
100 million 6⅔ cups 20 gallons use a sprayer
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How much do I need?

Length times width. A 50 by 100 foot lawn is 5,000 sq ft.

Enter the area to treat, in square feet.

We use one rate for every product and every pest: 25,000 nematodes per square foot. Not sure which nematode to use? See Which nematode do I need?

After you apply

You won't see the nematodes; they're too small. Once in the soil:

They find the pest

Nematodes enter the insect and release bacteria.

The pest dies

Usually within a day or two. The bacteria don't harm people or pets.

1–2 days

A new generation hunts

They reproduce inside the dead insect and come out to hunt more pests.

3–4 weeks
…and the cycle repeats. One application typically lasts about a year, often longer.

The best way to know when to treat again is to watch for the pests coming back. If you're still seeing damage, contact us and we'll help you figure out why.

More directions

Topdressing by hand

This is how Scanmask Topdressing and Ecomask Topdressing are meant to be used. Mixing the nematodes into a moist carrier protects them from heat, sunlight, and drying out. We've sold the same Scanmask formulation since 1985, and it's our recommendation for organic gardeners and homeowners.

  1. Add 1 cup of water to the nematode container and let it sit for 30 minutes at room temperature.
  2. In a bucket, mix peat moss, vermiculite, sandy humus, or potting soil with water: 5 quarts with 2 quarts of water for the Lawn & Garden size (10 million), or 4 gallons with ½ gallon of water for the Horticultural size (25 million).
  3. Add the contents of the container, rinse the container with ½ cup of water, and add that too.
  4. Mix thoroughly so the nematodes are spread evenly through the mixture.
  5. Water the area to be treated.
  6. Spread the mixture by hand over the affected areas, add it to seed furrows, or put it around transplants. The Lawn & Garden size treats about 400 sq ft, and the Horticultural size about 1,000 sq ft.
  7. Water again afterward to wash the mixture off the leaves.

To spray a topdressing instead, mix the contents with cold water (2 gallons for Lawn & Garden, 1 gallon for Horticultural), let it sit for 30 minutes so the carrier floats to the top, skim the carrier off with a fine strainer, and use the liquid in a pump sprayer or watering can. For Lawn & Garden, spread the 2 gallons over about 400 sq ft. For the Horticultural size, spread the 1 gallon over about 1,000 sq ft.

Chemical compatibility

Many common herbicides, insecticides, fungicides, and fertilizers are safe to use with our nematodes, but some need to be applied a week or two apart. The same chemical is sold under many different brand names, so look under "Active Ingredients" on the product's label to find the chemical name, then check the lists below.

The chemicals in the second and third lists shouldn't be applied at the same time as nematodes. Used a week or two apart, as listed, they shouldn't harm the nematodes.

Compatible (safe to use together):

  • Azadirachtin (neem)
  • Bacillus thuringiensis (Bt)
  • Benomyl
  • Bifenthrin
  • Bromine-chlorine
  • Chlorothalonil
  • Chlorthal-dimethyl
  • Copper hydroxide
  • Cyfluthrin
  • Cypermethrin
  • Diatomaceous earth
  • Dienochlor
  • Diflubenzuron
  • Esfenvalerate
  • Etridiazole
  • Fatty acids
  • Fenoxycarb
  • Fluvalinate
  • Fosetyl-Al
  • Glyphosate
  • Imidacloprid (it actually works better alongside nematodes)
  • Iprodione
  • Kinoprene
  • Metalaxyl
  • Methidathion
  • Methoprene
  • Nicotine sulfate
  • Oryzalin
  • Pentachloronitrobenzene (PCNB)
  • Permethrin
  • Pyrethrins
  • Rotenone
  • Thiophanate-methyl
  • Triadimefon
  • Vinclozolin
  • A wide range of soluble fertilizers

Use one week before or after nematodes:

  • Anilazine
  • Benzalkonium chloride
  • Fenarimol
  • Furalaxyl
  • Mercurous chloride
  • 2,4-D
  • Triclopyr
  • Malathion
  • Azinphos-methyl
  • Bendiocarb
  • Methomyl

Use two weeks before or after nematodes:

  • Carbofuran
  • Ethoprop
  • Isazofos
  • Fenamiphos
  • Oxamyl

Need to know the best time of year for your pest? See When to apply.