Also known as pot marigold, poet’s marigold, or English marigold, calendula is an easy-care annual that produces masses of cheerful, yellow or orange flowers from late spring until the first frost in autumn. While calendula grows like crazy with little effort on your part, the plants attract a number of good bugs, and are also susceptible to attack by certain harmful calendula pests. Read on to learn more about the good, the bad, and the ugly.
While there are a few troublesome pests of calendula, it’s also important to realize that calendula blooms attract a number of beneficial insects. For example, the sweet nectar draws pollinators such as butterflies and bees.
Calendula also attracts good guys such as ladybugs, lacewings, hoverflies and other insects that help control aphids, thrips, and other destructive pests. If you walk through your garden in spring and summer, you’re likely to see beneficial insects hanging around your calendula plants.
Calendula tends to be a pest magnet. This may sound like a bad thing, but look at it this way: If you grow calendula as a “trap crop,” the flowers will draw aphids, thrips, whiteflies, and other harmful pests away from more susceptible plants, like roses or vegetable plants.
If bugs that eat calendula, such as aphids, whiteflies, and thrips, are out of control and sucking the life out of your calendula plants, insecticidal soap spray will keep them in check, although you may have to apply the soap repeatedly to stay ahead of the pests.
Don’t use insecticidal soap when bees, ladybugs, or other beneficial insects are present on the plants; you don’t want to decimate ladybugs and other beneficial insects that help keep pests under control. Removing natural enemies just allows aphids and thrips to flourish.
Don’t spray insecticidal soap on hot days or when the sun is directly on the foliage, as doing so may scorch your calendula plants.
Slugs also feed on calendula plants. Remove slugs by hand if you aren’t squeamish. Keep the area free of plant debris and limit the depth of mulch, which creates a handy hiding place for slugs. You may need to use a commercial slug bait if your garden is host to a large slug population. Several organic products are now on the market.
Cabbage loopers are small caterpillars and they’re easy to remove by hand. Encourage songbirds to visit garden, and they will help you keep cabbage loopers in check. Also, remove plant debris in fall to eliminate sites where pupae tend to overwinter. If you need a little more help keeping cabbage loopers under control, treat them with Bt (Bacillus thuringiensis), a naturally occurring bacteria that kills loopers by paralyzing their digestive system. Avoid pesticides, which nearly always do more harm than good.
Finally, while not much of a threat unless found in high numbers, grasshoppers may be seen frequenting calendula plants in the garden. These can easily be picked off. Birds will also feast on these potential pests. If numbers are extreme, Nosema locustae can help.
Any gardener who has been at this for a while can tell you that dealing with pests is part of the deal. No one escapes this reality even expert gardeners face severe pest infestations from time to time.
The reason why pest prevention methods are so crucial is that preventing garden pests is far easier and less time consuming than dealing with pest outbreaks in your garden.
Then, we have the problem of pesticide sprays. We know that using pesticides is toxic to our soil health and the plants themselves. Also, if you spray pesticides on vegetable plants, it ends up in the food you feed to your family.
What about homemade and organic sprays? Are they safer?
Homemade and organic sprays contain fewer harmful chemicals, but pesticides of any kind can kill off beneficial insects that your garden needs, including pollinators. Killing beneficial insects and organisms damages your garden, as well as laters the pH balance of the soil. Some organic sprays even destroy the soil microbes that help your plants grow.
So, while these sprays are safer for human consumption, that doesn’t mean you want to spray your plants with anything.
Using all of the best pest prevention methods drastically reduces the chances you will ever need to use pesticides, homemade or not. Let’s look at how to prevent pests in your garden.
H E’S A GO-TO GUY when other seed companies want something special, but when Frank Morton of Wild Garden Seed seeks inspiration, he listens to the plants. “The plants showed me what they could do,” Morton says, “and what we could do together.” From his start as a “salad guy” growing greens for restaurants, Morton watched as new traits surfaced, and evolved into a lettuce breeder. From there the plants (and his financially practical wife, Karen) nudged him to become a seed company that grows everything it sells.
He also publishes what is “famously the world’s latest seed catalog” to drop each year, but he’s making no excuses. While other companies are sending out theirs, the Mortons are harvesting the seed those companies ordered from Wild Garden. I’ve gleaned a few of Morton’s plant lessons: about calendula, beneficial insects, and how home gardeners wanting to know just which lettuce to grow can set up their very own seed trial.
F RANK MORTON, whose certified-organic Wild Garden Seed farmland is in Philomath, Oregon, grew salad for 18 years for restaurants, “and that’s when I did my breeding,” he recalls. “I had thousands of seeds and plants going and suddenly there was a red one—an accidental cross between a red Romaine and a green oakleaf. But when I saved its seed, I didn’t get red ones, but traits from both parents.”
A lettuce breeder was born.
“Basically I learned from the lettuce where new varieties come from.”
He learned, too, in short order that different varieties perform best at different times of year, and also this:
“That the whole life cycle of a plant is part of the story.”
Take arugula, for instance, or chervil—both shown above–which most of us plant and harvest young and then pull up.
“Yes you use the leaves, but you can use the plant right though when blooms start,” says Morton, “and then the flowers attract beneficial insects.
“You don’t just eat the plant for your own food, but also to feed your ecosystem, to make your place attractive to your allies.”
Like the aphid-eating soldier beetles that love those chervil flowers, for instance—assuming you didn’t pull the plants!
Umbel-flowered plants (think: parsley, carrot, fennel) and those in the Mustard family (a.k.a. Brassicas, such as broccoli, turnip, radish) are especially attractive to beneficial insects, he observed, as are calendula, one of the things I asked him about in more detail, in this Q&A:
Q. When I began growing vegetables, there was not a year my plot didn’t include calendulas, or pot marigold (though of course they are not a marigold). Seeing your catalog photos of the Flashback series (that’s Solar Flashback mix, above) and now the new Citrus Sherbet Mix, and reading about calendulas with less-floppy stems in particular than back then, I long for them again, and wonder why I let them fade out.
You catalog has this further inducement about these easy annuals, that as I recall self-sow prolifically:
“In the field, blooms encourage a host of beneficial insects: minute pirate bugs for thrip control, syrphids for aphids, micro-wasps that parasitize aphids and caterpillars, and native fruit-pollinating solitary bees.”
Sounds good to me! So tell us about your affair with Calendula officinalis, please.
A. Calendula has always been part of my gardens, maybe thanks to John Jeavons suggestion in his book, “How To Grow More Vegetables Than You Ever Thought Possible on Less Land Than You Can Imagine,” which was my textbook in the beginning, back in 1980.
By time I began my salad career, I had learned about edible flowers and was enjoying the color fireworks of calendula on my salads. It was easy to begin the same genetic play with calendula as we were enjoying with greens.
By time Rob Johnston of Johnny’s Selected Seeds visited my garden for the first time, ‘Flashback’ calendula was in our seed catalog and all around the garden. Now, and for years, our various calendulas have dominated the Johnny’s selections.
Calendula is just fun, it takes care of itself, is always available when you want some, and has room for re-imagination and improvement. Powdery mildew is a worthy opponent to select against, and the flowers are full of surprises, worth prying forth.
Q. You told me not to ask you how to grow lettuce (or anything!) in my garden that you can’t advise gardeners everywhere how to grow a particular crop—even lettuce, which you know so well, but from the Oregon-based perspective. (That’s Wild Garden’s farm-original variety ‘Red-Earred Butterheart,’ above, one of 83 kinds they sell.)
A. Where I come up short in my expertise is cultural specificity, yes. How far apart to space lettuce? Well, that depends what you’re growing it for—to cut as baby greens, or as full heads?
“What’s the best lettuce for Florida?” people ask me, and I think, “How would I know?” Instead, I want to tell them how to run a seed trial in their gardens and find out for their location and conditions.
Trials can be super-easy and very informative. A simple “observation trial” can be as simple as 5-10 feet of row for each of several varieties you wish to compare. Plant the seed at the same time and treat each row the same way. By seeing the varieties growing side-by-side, you can’t help but learn their differences and what you like and dislike about each kind.
It is the simple fact of their “contemporariness” (being together in time and space) that reveals their comparative natures. This is something anyone can do in a small space.
Q. So what about when you conduct trials, as a professional? I assume it gets more complicated, but I’m curious.
A. More extensive trials would add “replications” of the observation plot, other identical plots in a different location. This isn’t necessary for most gardeners, but is critical for farmers, breeders or researchers who are trying to distinguish highest yield, best disease resistance, or other fine points of distinction that are not obvious when looking at just a few plants.
If one needs to employ statistics in comparing varieties, then the number of plants grown in each replication needs to be at least 27 to give meaningful results. The higher the numbers, the more replications, the more reliable the results in teasing out differences that are not apparent in a simple observation trial.
B ECAUSE OF THE MORTONS’ view of a farm or garden as a complex community or ecosystem, you’ll find lots of information about the interaction between the plants and other creatures in the website and catalog descriptions, and also lots of other “aha’s.”
A for-instance: that lettuce is “one of the very oldest garden plants,” and though misunderstood as being low in nutrients, is actually not. “Crisp-leaf head lettuce is one of the richest vegetable sources of choline (an essential brain nutrient) in the normal American diet,” says the website. “Get focused. Eat lettuce.” My advice: sit down for a good read with a salad and the Wild Garden Seed website or catalog soon.
I’ VE PURCHASED TWO $20 gift certificates from Frank and Karen Morton at Wild Garden Seed to share with you. (UPDATE: The giveaway is now closed, but your comments are always welcome.) To enter, simply comment below by answering the question:
Is there a plant in your garden that you’ve noticed is a lure for “good bugs,” that perhaps you let go to flower accidentally or on purpose?
My answer: I always let my parsley go by, and dill is another real magnet—and last year I let carrots and turnips stay and bloom, too, and it was the place to be if you were an insect. Fascinating.
Don’t have an answer right now, or feeling shy? Just say, “Count me in” and I will, no worry. I’m easy. I’ll pick two winners at random after entries close after midnight on Sunday, February 3, 2013. Good luck to all.