Most gardeners grow calendulas (Calendula officinalis) for their bright orange to yellow summer flowers, but calendulas are much more than a pretty face in an organic vegetable garden. Calendula flowers can be harvested and used as a medicinal herb, and I like to snip petals into herb teas and salads to add color and nutrition. In addition, the presence of calendulas in the garden may help repel insect pests, and calendula roots benefit the soil by forming active relationships with soil fungi. Best of all, I can get calendulas to come back year after year by scattering seed heads where I want the next crop of flowers to grow. Calendulas grow so vigorously in my garden that I have often used them as a fall cover crop that is conveniently killed by cold winter weather. Where winters are mild, plants often survive to bloom in spring.
Medicinal Uses for Calendula Flowers
Calendula flowers have a long history of use as the source of natural compounds that help heal injured skin. The plant profile from the University of Maryland Medical Center reports that the abundant antioxidants in calendula petals help heal skin wounds, rashes and burns by increasing blood flow to the affected area while suppressing secondary infections. Calendula is an active ingredient in several diaper creams for babies, and you will often see it in natural hand lotions and first-aid creams.
The first step in making your own calendula preparations is to dry a quantity of calendula flowers. Dried calendula flowers that are not used in medicinal preparations can be fed to chickens in winter, which helps produce darker egg yolks.
I gather calendula flowers late in the morning, when they are fully open and the dew has dried, and let them dry indoors at room temperature for a few days. Then I remove residual moisture by placing the shriveled blossoms in my dehydrator or a warm oven for a couple of hours. The dried flowers are then ready to store or make into an infused oil. This is easily done by tightly packing dried flowers into a clean jar, covering them with olive oil or grapeseed oil, and placing the jar in a warm, sunny window. Shaken every day, the oil is ready to strain through a coffee filter and store in 3 to 4 weeks. The infused calendula oil can be used straight-up for rashes, you can mix it with your favorite skin cream, or you can use it as a primary ingredient in a homemade lotion.
One precaution: People who are allergic to daisies, ragweed and other close cousins could react negatively to calendula preparations. I am highly allergic to ragweed, but calendula does not bother me a bit. Perhaps I've grown desensitized by using calendula petals as "poor man's saffron" in rice and pasta dishes.
How Calendulas Help the Garden
I see occasional insects visiting my calendula flowers, but most insects avoid the plants, which is in keeping with one of its old uses as the basis for insect sprays. The idea of brewing up calendula tea from the plants' flowers and leaves, and using it as an insecticidal spray, is getting renewed attention based on several recent studies. In Poland, growing calendulas among cabbage resulted in fewer problems with aphids, cabbageworms, and diamondback moths. A recent study in India showed that calendula extract reduced feeding by tobacco cutworms.
Calendulas also benefit the garden below ground, where they form partnerships with soil-borne fungi that turn the plants into soil-cleaning machines. In China and the USA, calendula has been found to be useful in the restoration of soil contaminated with high levels of cadmium. In Columbia and Spain, cover crops of calendula were found to suppress root-knot nematodes.
What exciting news! In my climate, calendulas sown in spring produce an abundance of seeds by midsummer. I often use them as a fall cover crop, just because they want to grow that way. The calendulas I sow in vacant space in late summer hardly have time to pop a few flowers before winter shuts them down, and then they go on to feed the soil. With so many talents, calendulas deserve a place in every garden.
By Barbara Pleasant