Believe me: I’ve had ample opportunity to test advice about pests in the last couple of years.
First: be cautious: even if some things are considered “organic” they aren’t necessarily ok for frogs or fish populations. And some proposed solutions (such as those involving tanglefoot products) kill all insects including beneficial insects that control problem insects.
1. Start out right: grow in soil that is 6.3-6.9 (note that if you’ve got lead in your soil it’s recommended that you grow in neutral soil — close to 7.0). Add lime or wood ash (from untreated wood) every 1-2 years — our soil tends to be unbalanced because of the rain. Add compost (1-2 inches/year) and/or organic fertilizers (especially one called the NW Mix) to encourage plants to “outgrow” damage and to develop their own defensive mechanisms (one source says every three months; another recommends 1/4 to 1/2 inch before planting each crop; others tend to use it if the plants look like they are slowing down.)
2. Adjust your expectations: you’ll not get rid of the critters entirely, but you may be able to keep damage to minimum. If it starts getting really bad (e.g. cabbage loopers or aphids): it’s time to compost the plant.
3. Trellis vining veggies, tomatoes, & beans.
4. Visit your garden often and promptly remove anything that looks suspicious. I know it’s yucky: stomp & squash cut worms, slugs, and snails. If you must: use a soap spray daily (and wash the veggies before you eat them). (Most of the recipes around recommend 1 Tbsp non-toxic soap — read the label — and 1 tsp canola oil per quart or two of water.) I used a garlic tea as a spray for a while: but everyone complained about the odor!
5. Use “traps“: aphids prefer nasturtium instead of your green beans. Plant flowers that attract beneficial insects or which otherwise help to control the bad guys: eg heirloom marigolds, hyssop, alyssum, sunflowers, herbs such as parsley. Consider scarlet runner beans (beloved of hummingbirds) and letting some of the radishes bloom and go to seed. Interplant with onions and/or garlic.
6. Physically exclude the pests: use row covers from first planting, and elevated beds. Backyard apple growers are using what we used to call nylon “footies” and putting them around the baby apples before the flies and moths can start laying their eggs (i.e. about the first part of May for most of us.)
6. Time your planting: Plant after or before the pest’s own eating season: e.g. carrot rust fly (plant mid to late May); root maggots (plant after solstice for an Autumn crop).
7. Rotate crops (there’s lots of information out there).
Sources: Washington State University Extension Master Gardener Program (Fact Sheet # 13) (kingcountyMG.org), Lettuce Link’s publications (see their website), lecture from Colin McCrate (Seattleurbanfarm.com), books What’s Wrong with my Vegetable Garden (Deardorff & Wadsworth, Timber Press 2011) and The Organic Gardener’s Handbook of Natural Pest and Disease Control Bradley, Ellis, and Martin, Rodale, 2009), The . There are also periodic postings on the city of Seattle’s List Serve that have been quite helpful. I’m happy to dig additional information out of the books (or let SGGN members borrow them.) Just Ask! And It’d be really wonderful if you add your own comments!