maragolds have some pest-repelling properties and can definatly be helpful. the others may not really "help" anything but certainly wont hurt. they'll make the garden look prettier too!

Parasitic wasps provide an immense, though often overlooked, benefit by parasitizing and killing many pest insects. Many of these are very tiny. You can encourage these by planting plants that have very tiny flowers and produce nectar for them to feed on. Many plants in the parsley family are suitable including dill, fennel, coriander, Queen Ann's lace, etc. Yarrow is another good nectar source, though this can become invasive.

On the other hand, the pest repellency of marigolds is greatly overrated. They are even attractive to some pests such as earwigs.

If you are growing out-breeding plants, you will want to attract pollinators. Flowers that are strong producers of pollen or nectar, and bloom over long periods, are best for this purpose. I believe that color alone is a relatively small factor.

Flowers provide a food source for some beneficial insects, such as the wasps mentioned above. Those that bear plentiful seed (like sunflowers, dill, and cosmos) will also attract birds; whether the birds attracted will also eat harmful insects is another question.

If you are saving vegetable seed, plantings of flowers between different cultivars of the same species may reduce the chances of cross-pollination. This works well for inbreeding species like beans & tomatoes.

I have read of some flowers being used as "trap crops", to draw harmful insects away from vegetables; but most of these recommendations were anecdotal.

In the vegetable garden, I try to limit flowers to "bee plants". Sunflowers would qualify. I'm not certain that petunias & marigolds have any beneficial effects, beyond their aesthetic value. I remember reading about marigolds grown as a cover crop, to reduce nematodes I believe; but that would require a major planting.

There are also vegetables that are not commonly grown, that do triple-duty. Scarlet runner beans, purple basil, and bitter melon are attractive, edible, and good bee plants.

Hi I'm new to botany but I've gardened all my life. I planted tomatoes,strawberries,eggplant and peppers intermixed with my mostly native TX xeriscape. My yield on strawberries was about 80%. My yield on Tomatoes was about 75% and the peppers were 100%. No herbicides,pestacides or fertilizers. Just heavily composted soil.I used soaker hoses. Most of the fruit that had been attacked by pests only had one or two bites out of them. Strawberries'fruit is usually totally comsumed so I'm guessing whatever was eating the fruit got eaten while eating. PJ

Here are observation of few flowers that I have planted in my vegetable garden.There are red,white and yellow flowers in the garden. Garden is free from many insects harmful to plants, garden looks neat and clean from pest.None of the pollinators were affacted.
Only problem I got was from Japanes Beetles on egg plants and okra that was taken care by Sevin.
Yellow flowers are dominant in the garden mostly from Sun flowers and Bitter melon plants.