Spring, summer, and fall gardens might be ideal for more growth, but winter gardens are nice for the simple fact that there are only three main pests to worry about. Slugs, aphids, and imported cabbageworm can cause some trouble, but keeping them under control is not hard if you know what to look for.
Slugs are particularly active at night in cool, wet weather. They can be particularly troublesome for seedlings and young plants. Slugs hibernate during the winter in topsoil, but in the few months preceding and following the frost, they can cause a lot of problems. They can be controlled by hand picking them in the evening, trapping them with a shallow pan of beer, or making barriers around raised beds with copper tape. If you have chickens or ducks, they will also eliminate slugs quite handily.
For the best results, use a combination of some of the above methods plus using commercial slug bate with Iron phosphate. Sprinkle this bait about once every two weeks while you have seedlings. If you have children or pets, be sure to avoid brands that include metaldehyde because it is poisonous to dogs, cats, and children.
Aphids can attack winter plants as well. You can combat them by removing leaves they are on or spraying with an insecticidal soap once a week or so. Ladybugs also love an aphid feast, so if it is warm enough you can bring some in to help control the problem (though ladybugs tend to hibernate in winter).
Imported cabbageworm loves everything in the cabbage family. As adults, they become white butterflies with black spots. Their larvae (worm) babies eat holes through leaves and florets. The best way to control them is to inspect leaves for small yellow eggs before transplanting seedlings into the garden. Scrape any eggs you find off and then cover the seedlings with a fabric row cover to keep the adults from laying eggs on them. Check weekly for evidence of worms on the underside of leaves.
If you can keep these three pests at bay, you’ll be one step closer to a thriving winter garden.