Tomato HornwormTomato hornworms are like something out of a horror flick: big, green, horned and with an appetite that doesn’t seem to stop. You don’t forget your first tomato hornworm. And you shouldn’t. It will help you remember your fall to-do list for protecting next year’s harvest.

Where Do Tomato Hornworms Go in Winter?

Hummingbird MothThese 4-inch-long munching machines are the larvae of hummingbird, or sphinx, moths, which magically hover beside blooms at dusk sipping nectar. These elegant – but destructive – fliers seeks out tomato plants in which to lay their eggs, which hatch into hornworms. After a hornworm feasts on tomato plants, it burrows into soil where it will shift into a dark brown pupa, called the resting stage. The pupa remains in the soil all winter long, awakens in spring and emerges as a moth.

Tomato hornworms spend winter buried underground, which is information you can use to your advantage when it comes to controlling garden pests. Many other vegetable garden pests also pass colder months tucked into soil, including squash vine borers, Colorado potato beetles, cabbage maggots and cucumber beetles. Typically insects bury themselves 2 to 10 inches deep.

Understanding where pests go in winter can help you break the cycle of their attack. Fall is a key time to take action. Follow these steps to start controlling next year’s garden pests now.

Tackle Garden Cleanup

After harvesting crops, remove all plant debris from the vegetable garden. While many pests dig into soil for winter, others are content to shelter beneath leaf litter. Many vegetable garden diseases overwinter in a resting state on previously infected plant material. Pull spent vegetable plants – and weeds – to eliminate places where pests and diseases can hide.

Don’t toss diseased or insect-infested plants into your compost pile. Most homeowner compost piles don’t get hot enough to destroy all problem organisms. Dispose of plant debris with yard waste that’s composted at a local landfill, where giant composting piles heat up enough to kill problem organisms.

Clean plant supports and trellises with a 10 percent bleach solution. If possible, store supports outside for winter in cold climates to allow freezing temperatures to destroy insects or diseases.

Till

Till soil after frost to expose overwintering organisms to cold temperatures. You can even cover soil with a layer of fallen leaves first and till them into soil, where they’ll decompose and enrich soil. Many gardeners prefer fall tilling because:

  • soil tends to be drier than in spring
  • it prepares soil for early spring planting

For maximum killing effect, till just before a hard frost.

If you follow no-till gardening practices and mulch soil with several feet of leaves to keep worms active longer into winter, garden cleanup is your first line of defense against pests. During the garden season, monitor plants carefully for pests and diseases.

Plan Ahead and Rotate Crops

Before pulling all crops, draw a rough sketch of what was planted where this year. Over winter, decide next year’s garden layout. Move plants around so tomatoes aren’t growing in the same spot next year. That way, when pests emerge from soil in spring looking for their favorite plant, they’ll have to travel to find it. The journey exposes them to predators and the elements, either of which can kill them.

Research Your Nemesis

Cozy up with your computer or a good gardening book this winter to learn about the problem pests you battle in your garden. Discover the details of their life cycles and use that knowledge to develop effective preventive strategies.