These factors include sun exposure, weather, ecology, pollinators, insect population, soil structure and chemistry, and water supply.West Coast Seeds has conducted significant research into these companion planting guidelines and has defined the best possible results and reasons for each of our recommendations.Minimizing Risk: Companion planting increases odds of higher yields even if one crop fails or is affected by natural hardships like weather, pests, or disease.Trap Cropping: Companion planting is the ultimate organic pest management system.Ammi - This beautiful flower attracts lacewings, ladybird beetles, and parasitic wasps.Basil helps repel aphids, asparagus beetles, mites, flies, mosquitoes, and tomato horn worm.Plant with Brassicas, carrots, celery, chard, corn, cucumber, eggplant, peas, potatoes, radish, and strawberries.Plant with bush beans, Brassicas, corn, garlic, kohlrabi, leeks, lettuce, and mint.Brassicas (broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, kohlrabi, turnip) – All benefit from chamomile, dill, mint, rosemary, and sage.Buckwheat – Fixes calcium in the soil, and makes an exceptionally good green manure plant.Calendula – Repels a number of unwanted soil nematodes and asparagus beetles, but may attract slugs.Celery – Good partner for beans, Brassicas, cucumber, garlic, leek, lettuce, onion, and tomatoes.Coreopsis - This plant attracts pollinators, but also hoverflies, soldier bugs, and tachinid flies.Amaranth makes a great mulch between rows by competing with weeds and conserving ground moisture.Cosmos can be direct sown from early March to the end of June in our region so that it blooms continuously throughout the summer.Cucumber – Plant beside asparagus, beans, Brassicas, celery, corn, dill, kohlrabi, lettuce, onion, peas, radish, and tomatoes.Dill attracts ladybird beetles, parasitoid wasps, hoverflies, bees, and garden spiders, making it one of the most useful companion planting candidates.Echinacea - These perennial coneflowers attract hoverflies and parasitoid wasps, so they're useful for pest control in companion plantings.Eggplant – A good companion for amaranth, beans, marigolds, peas, peppers, spinach, and thyme.Fennel attracts hoverflies, ladybird beetles, parasitic wasps, and tachinid flies, so it's a kind of beneficial insect magnet.Gaillardia - This flower blooms over a very long period in summer, providing a rich source of nectar for a host of pollinators.Because of its sulfur compounds, it may also help repel whiteflies, Japanese beetles, root maggots, carrot rust fly, and other pests.Garlic, made into a tea, or spray, will act as a systemic pesticide, drawing up into the cells of the plants.Iberis - This early flowering plant provides nectar for pollinators before many others, and it attracts hoverflies and ground beetles.Lettuce – Good companions for beets, Brassicas, carrot, celery, chervil, cucumbers, dill, garlic, onions, radish, spinach, squash, and strawberries.Melon – Great companions for corn, marigolds, nasturtiums, pumpkin, radish, squash, and sunflowers.Onions also work well alongside beets, Brassicas, carrots, dill, kohlrabi, leeks, lettuce, strawberries and tomatoes.Peas – Superb companions for beans, carrots, celery, corn, cucumber, eggplant, parsley, peppers.Phacelia — An essential element in any organic gardener's toolkit, this multi-purpose annual flower is fast to mature, and amazingly attractive to a host of pollinators and beneficial insects.Notably, it attracts bees and predatory hoverflies to improve pollination and combat pest insects.Plant Phacelia around any crop showing poor pollination, particularly squash (including zucchini and pumpkin), melons, and cucumbers.Avoid planting potatoes near asparagus, Brassicas, carrots, cucumber, kohlrabi, melons, parsnips, rutabaga, squash, sunflower, and turnips.Rosemary repels cabbage moths, Mexican bean beetles, and carrot rust flies.Spinach – A good companion for Brassicas, eggplants, leeks, lettuce, peas, radish, and strawberries, particularly.Couple them with beans, borage, garlic, lettuce, onions, peas, spinach, and thyme.Sunflowers are attractive to a host of wild and domestic bees, and also ladybird beetles, which prey on aphids.Tithonia - Plant this so-called Mexican Torch to attract parasitoid wasps, parasitic flies, and soldier bugs to your garden.Tomatoes – Another sensitive plant when it comes to companions, tomatoes benefit from asparagus, basil, beans, borage, carrots, celery, chives, collards, cucumber, garlic, lettuce, marigold, mint, nasturtium, onion, parsley, and peppers.Yarrow – Its scent repels aphids, but attracts hoverflies, lady beetles, and wasps that prey on garden grubs.The leaves and stems of yarrow contain enzymes that break down rapidly, so it can be added to the compost raw or as a tea to accelerate the heap.Damp, acidic soil can host club root (for example), which can be a real problem for broccoli and Brussels sprouts.Please feel free to contact us for clarification at [email protected] westcoastseeds.com, and we will do our best to bring better depth to our guides so that all of our customers can benefit