Gardeners who are looking for a more organic gardening experience, often turn to green alternatives to harsh chemicals when looking to feed and protect plants. The alternatives to chemical fertilizers are easy to find, but finding organic options to pesticides are much more difficult. Pairing the right plants can help expel pests and also attract helpful insects to your space.
Your grandmother may tell you that marigolds circling the veggie garden will keep the rabbits out, but no scientific study has ever proven it. (Just as many people swear rabbits will eat their marigolds as those who swear they work as a repellent in many studies.) What marigolds will do is protect nearby plants from nematodes, microscopic organisms that can be both harmful to plants and animals. Parasitic nematodes can include heartworms, pinworms and hookworms among others.
Marigolds also are beneficial to the garden because they attract beneficial insects such as lady bugs and lacewings that feast on aphids and other destructive bugs. Plant marigolds as a companion to tomato plants to help attract these helps where they're most likely to find their meals.
Nasturtiums are a group of gorgeous flowers that spread or trail, depending on variety, and is a must when it comes to companion planting. Nasturtiums repel cucumber beetles, woolly aphids, whiteflies and a number of other pests. Allow trailing varieties to grow up fruit trees or climb with cucumbers and squash on a trellis while bushing varieties grow well intermingled with cabbage, tomatoes and root vegetables. Nasturtiums are also edible-- sprinkle leaves and blooms in salads for a sweet crunch.
Four O'Clocks, with their petunia-like trumpet-shaped blooms, are an annual that opens its blooms daily in the evening. Like the petunia, four o'clocks attract Japanese beetles by the droves, but, unlike petunias that just get devoured, four o'clocks have a poisonous enzyme in their foliage that kills the pests. Plant with care though-- four o'clocks' foliage can harm pets and children as well if ingested.