Culinary Herbs are Good for Beneficial Insects, Including Pollinators
The definition of an herb can be incredibly broad. Holly Shimizu’s definition on the website of the Herb Society of America states, "Herbs are defined as plants (trees, shrubs, vines, perennials, biennials or annuals) valued historically, presently, or potentially for their flavor, fragrance, medicinal qualities, economic or industrial use, or in the case of dyes, for the coloring material they provide." The Merriam Webster dictionary defines an herb as "a plant or plant part valued for its medicinal, savory, or aromatic qualities." This article will focus on commonly known and easy-to-grow culinary herbs, such as calendula, lavender, basil, marjoram, oregano, sage, mint, cilantro, fennel, parsley, chives, garlic chives, borage, dill, and rosemary.
Native plants are broadly considered to be the best plants for supporting our native pollinators. However, none of the culinary herbs discussed here are native to Pennsylvania. Many of these herbs provide excellent functional support to pollinators and other beneficial insects. A few herbs are host plants. Some provide nectar and pollen, as well as shelter and nesting sites. It must be mentioned that in order to provide a healthy insect habitat, the gardener may need to adopt some new practices or change some existing ones.
A good rule of thumb is to plant twice as much as you need to support pollinator populations with herbs. Grow half for yourself and half (or more) to share with them. Parsley, dill, fennel, and cilantro are all host plants for black swallowtail butterflies (Papilio polyxenes asterius). Borage is the larval host of the painted lady butterfly (Vanessa cardui). If you grow these herbs, be prepared for the possibility that they will be covered with hungry caterpillars. If the damage bothers you, choose a less noticeable area in your garden and plant them there.
Adapt your harvest schedule for preserving the leaves of herbs so that your main harvest is in early to mid-summer. After that time, allow some or most of the herbs to flower. The leaves of herbs that are in flower have less quality for culinary use. Yet, the flowers are a very nutritious source of pollen and/or nectar for many pollinators and other beneficial insects. An oregano or marjoram in bloom in my garden is always covered with bees.
A few herbs are grown for the flower, such as lavender, borage, and calendula. Keep deadheading calendula and borage to keep the flowers coming for both the pollinators and yourself. I am always torn when it comes to harvesting lavender. For culinary purposes, it is best to harvest the flowers of lavender when the buds are full but right before they open. The floral spikes can easily be dried and, once dry, stripped from their stems and stored in an airtight container in a cool, dark, dry location. If I delay the harvest until the flower buds open, the flower spikes become covered with bees, and I feel guilty about removing their source of food. I try to harvest half and let the bees have the rest.
Many herbs flower in clusters -- a trait that bees especially love because they can conserve energy by finding so many flowers in one concentrated area. Fennel, dill, marjoram, oregano, mint, lavender, sage, and basil all provide either spikes or umbels of clustered flowers. Pollinators are also drawn to the flowers of rosemary, chives, and garlic chives. Butterflies love calendula, as the flat flowers provide a natural landing pad.
Herbs help support many beneficial predatory insects. Chamomile, cilantro, and oregano provide nectar and pollen for ladybugs, lacewings, minute pirate bugs, parasitic wasps, syrphid flies, soldier beetles, and tachinid flies. Add angelica, dill, and lovage for a more substantial and healthy impact on their habitat.
Besides changing your harvest schedule, the following are additional ways to provide a healthy habitat for these insects.
- Provide a water source for pollinators, such as a bird bath or butterfly puddling pool.
- Provide nesting sites by leaving some bare patches of soil, wood piles, and stone piles or walls.
- Limit pesticide use throughout your garden. Even some organic pesticides have an adverse effect on insects.
- Postpone the annual fall cleanup until spring. Plant stalks and stems provide shelter, especially over the winter. Delay your garden cleanup as long as you can tolerate it until April.
- Eliminate invasive species of plants in your garden as they out-compete important native plants.
Herbs are a wonderful addition to the home garden, providing beauty there and flavor in the kitchen. They are also a boon for many beneficial insects, including pollinators, as these useful plants provide larval food, nectar, pollen, and even shelter.
For further information on providing a healthy pollinator habitat:
