Free shipping on every order. Ships Monday–Wednesday, so it never sits over a weekend.
Cart
Menu

When to apply beneficial nematodes

The best season and time of day to apply BioLogic nematodes for each pest, from early spring through fall, plus tips for hot summer weather.

The short answer

  • Anytime the soil isn't frozen

    For most pests, and for prevention. Some pests have a best window.

  • Late afternoon or evening

    Sunlight and heat harm nematodes, so avoid the middle of the day.

  • Water before and after

    Water the area well before you apply and right after.

Some pests have a best window, based on when their larvae are in the soil and easiest for nematodes to reach. White grubs are the big example. See How to apply for the step-by-step directions.

Through the seasons

Spring

As a general rule, you can apply nematodes in early spring as soon as the soil is no longer frozen. For most pests, early spring is a great time for a first line of defense.

If a hard frost is on the way, wait a day or two before you apply. Freezing the package kills the nematodes, so never leave it anywhere it could freeze.

Nematodes can be applied in cold soil, but they may not become active until the soil warms up. How warm it needs to be depends on the nematode:

Active in soil from…

Soil temperature, not air temperature. Below this, nematodes wait in the soil until it warms up.

  • Scanmask55°F and upWorks in early spring and cool fall weather
  • Heteromask68°F and upLess effective in cooler soil
  • Ecomask68°F and upDoes especially well in hot, dry climates

Frozen soil: don't apply

Spring timing matters most for pests that attack new plants, like cutworms, cabbage root maggots, onion maggots, and wireworms. Treat the soil before or at planting time.

White grubs: late summer and early fall

White grubs, including Japanese beetle and European chafer grubs, have a one-year life cycle (May and June beetles take 2 to 3 years). The adult beetles lay eggs in summer, and the eggs hatch within a few weeks. The young grubs feed through late summer and fall, spend the winter in the soil, then feed again in early spring before they turn into beetles.

When to treat white grubs

  1. Jan
  2. Feb
  3. Mar
  4. Apr
  5. May
  6. Jun
  7. Jul
  8. Aug
  9. Sep
  10. Oct
  11. Nov
  12. Dec

Best: young grubs near the surface Second chance: before they turn into beetles

Late summer and early fall is best because the grubs are small, young, and feeding near the surface, where nematodes can easily reach them. Spring treatment works too, but it's harder to time: the grubs are bigger by then, and they need to be treated before they change into beetles.

Heteromask is our recommended nematode for white grubs. Heteromask needs soil at about 68°F or warmer, so Scanmask is a better choice when the soil is still cool.

Summer

Many pests are well controlled with summer applications, including fleas, sod webworms, and flea beetles. Nematodes can work even in very hot, dry climates if you protect them from heat and drying out:

  • Put the package in the refrigerator as soon as it arrives. Never put it in the freezer. See Shipping and arrival for how we pack your order to keep it cool.
  • Apply in the evening, never in direct sun.
  • Water the area well before and after you apply.
  • Don't let the area dry out completely, especially in the first couple of weeks. Water it now and then if it's hot and dry.

Ecomask does especially well in hot, dry climates.

Fall and winter

Late summer and fall is the time for white grubs and crane flies. Keep treating anytime the soil is not frozen.

Once the outdoor season is over, nematodes still protect indoor plants. Fungus gnats in houseplants, greenhouses, and interiorscapes can be treated any time of year. Treat new plants before you bring them in, since they're often already infested.

Treatment calendar

Each pest's best timing, from our printed directions. Click a pest for what it looks like and how to treat it.

PestUseWhen to treatWhere
Annual Bluegrass WeevilEcomask SprayMarch to September.Thatch and the top inch of soil in short-mown annual bluegrass, especially along the edges of fairways, greens, and paths.
ArmywormsEcomask SprayMay to September.The damaged area and the healthy grass just ahead of it, where the larvae are moving. Apply in the evening, when they feed.
Artichoke Plume MothEcomask SprayApril to September.Soak stumps before planting. Drench the crown and stem bases of established plants, and the soil around them.
Banana MothEcomask SprayAnytime the larvae are active.Drench the potting mix and spray the stem base and any bore holes.
Banana WeevilEcomask SprayAnytime the larvae are active.Drench the soil around the plant base and corm. Pour into cut stumps and pseudostems (the trunk-like stems) after harvest.
BillbugsHeteromask SprayMay to August, or early spring and late summer.Areas of lawn that show damage, especially sunny areas along sidewalks and driveways, where damage usually starts.
Black Vine WeevilScanmask SprayEarly spring through June, or late summer and early fall, while the larvae are feeding.The drip zone (the soil under the outer edge of the branches) of affected shrubs and plants.
Cabbage Root MaggotScanmask SprayMarch to June.Transplants or rows of cabbage-family crops and root vegetables.
CarpenterwormScanmask SprayAnytime the borers are active.The trunk and limbs around active bore holes, where fresh frass and sap show. Wet the bark and the holes thoroughly.
Citrus Root WeevilHeteromask SprayMid-July through September, when the soil is above 70°F and moist.Moist soil under the tree canopy, followed by plenty of water.
Click Beetle (Wireworms)Scanmask SprayMarch to June, or at planting time.Around crops.
Codling MothEcomask SprayMarch to September.The lower 5 feet of the trunk, where the larvae spin their winter cocoons in bark cracks. Keep the bark wet for several hours.
Corn EarwormScanmask SprayJune to August.Spray the soil around and under corn and tomato rows, and the ground where fallen ears and fruit lie.
Cranberry GirdlerEcomask SprayMay to October.Spray the soil and thatch over the affected area, then water it in.
Crane FlyScanmask SprayMarch to June or August to September. Fall is best.Moist areas of the lawn, and any areas that show damage.
Cucumber BeetlesScanmask SprayMarch to July.Spray the soil in a band around the base of cucumber, squash, and melon plants, and water it in.
Currant BorerScanmask SprayMarch to September.Spray the canes, especially near the base and any cut or pruned ends, until wet. Prune out and destroy wilted canes.
CutwormEcomask SprayMarch to July, especially before seeding or planting.The area you're about to seed or plant.
Diaprepes Root WeevilEcomask SprayMid-July through September, when the soil is above 70°F and moist.Moist soil under the tree canopy, followed by plenty of water.
Dogwood BorerScanmask SprayMarch to July, or September.The lower trunk (about the bottom 10 inches) and the base of the tree, including rough bark and burr knots on the rootstock.
European ChaferHeteromask SprayMarch to June or August to September. Late summer and early fall is best.Areas of lawn or turf that show damage.
FleaEcomask SprayAnytime the soil is not frozen.Shady areas, around buildings and structures, under decks and porches, and wherever your pets spend the most time.
Flea BeetleScanmask SprayMarch to August. Treat as early in spring as you can.Rows, or around transplants and seedlings.
Fungus GnatScanmask SprayAnytime. Indoors and in greenhouses, any time of year.The soil of potted plants. In a greenhouse, treat the entire greenhouse or plant inventory.
Giant Palmetto WeevilEcomask SprayAnytime the larvae are active.Drench into the crown and leaf bases at the top of the palm, and around any wounds or bore holes.
Grape Root BorerHeteromask SprayAnytime the pests are active.The soil at the base of the vines, drenched with a sprayer.
Hairy Chinch BugEcomask SprayAnytime the soil is not frozen.Spray the damaged patches and a few feet of green grass around their edges.
Iris BorerEcomask SprayApril to July. Late May to early June is best.Around the rhizomes of iris plants.
Japanese BeetleHeteromask SprayMarch to June or August to September. Late summer and early fall is best.Areas of lawn or turf that show damage.
Masked ChaferHeteromask SprayMarch to June or August to September. Late summer and early fall is best.Areas of lawn that show damage and areas in full sun, plus the drip zones of shrubs and trees.
Mint Flea BeetleEcomask SprayApril to May.Spray the soil in the mint bed and water it in.
Mint Root BorerEcomask SprayApril to May, or August to early October.Spray the soil of the mint bed and water it in so nematodes reach the rhizomes.
Mole CricketEcomask SprayAnytime the soil is not frozen.Areas of lawn with tunnels or damage, especially in sandy soil.
Navel OrangewormEcomask SprayApril to May or August to October.The orchard floor where leftover (mummy) nuts lie, then irrigate.
Northern Corn RootwormScanmask SprayLate May to mid-July, while the larvae are in the soil.Around crops.
Onion MaggotScanmask SprayMarch to August.Rows, or around transplants.
Oriental BeetleHeteromask SprayMarch to June or August to September. Late summer and early fall is best.Areas of lawn that show damage and areas in full sun, plus the drip zones of shrubs and trees.
Peach Tree BorerScanmask SprayMarch to August.The soil around the trunk and drip zone (the area under the outer edge of the branches).
Pine WeevilScanmask SprayApril to August.Drench the soil around and over freshly cut pine stumps, and the soil at the base of young seedlings nearby.
Poplar Clearwing BorerScanmask SprayAnytime the borers are active.The lower trunk and the bark at the soil line until wet, especially around active holes, and the soil right at the trunk base.
Raspberry Crown BorerScanmask SprayMarch to September.The soil at the crowns and the base of the canes, drenched.
Root-Knot NematodeScanmask SprayAt planting time or before, before knots form on the roots.The soil where you'll plant, or around transplants.
Shore FlyEcomask SprayAnytime shore flies are present.The surface of wet growing media and anywhere algae grows, such as benches and floors.
Small Hive BeetleHeteromask SprayAnytime the pests are active.Drench the soil under and in a few-foot ring around each hive. Keep the spray off the hive and the bees.
Sod WebwormEcomask SprayAnytime the larvae are active.The thatch in and around damaged patches, especially their edges, where the larvae gather. Apply in the evening.
Southern Corn RootwormScanmask SprayLate May to mid-July, while the larvae are in the soil.Around crops.
Spongy MothScanmask SprayApril to July.Spray the lower trunk, any burlap hiding bands, and the leaf litter under the tree in the evening.
Squash Vine BorerScanmask SprayMay through July.The soil around the base of squash and pumpkin vines.
Strawberry Root WeevilEcomask SprayMid to late August, while the soil is still warm. Early May can also help. With Scanmask or Heteromask, March to June.The soil at the strawberry crowns, kept moist, applied in the evening or on a cloudy day.
Sugarcane BorerEcomask SprayAnytime the larvae are active.Stalk bases, leaf sheaths, and the crop debris left after harvest.
Sweetpotato WeevilScanmask SprayMarch to June, or mid to late summer from about 6 weeks after planting.Spray the soil along the sweet potato rows and around plant crowns, and water it in. Keep soil moist and fill cracks.
Tobacco BudwormScanmask SprayMarch to September.Spray the soil in flower beds and containers under petunias, geraniums, and other host plants.
Western Corn RootwormScanmask SprayLate May to mid-July, while the larvae are in the soil.Around crops.
Western Flower ThripsScanmask SprayAnytime the soil is not frozen, especially in the warmer months when thrips are the biggest problem.The soil or growing media under the plants, where thrips pupate.
White GrubsHeteromask SprayMarch to June or August to September. Late summer and early fall is best.Areas of lawn that show damage and areas in full sun, plus the drip zones of shrubs and trees.

Not sure what's eating your plants? Browse the Pest ID pages, use Which nematode do I need?, or contact us.