The humble marigold is often the favorite flower of vegetable gardeners, and there’s a great reason: marigolds help to keep many different pests at bay. They flower near-continually from late spring through the fall as long as you remove spent blooms. And they’re pretty.
But how do marigolds create that pest-eliminating environment? Are there plants that you shouldn’t grow around marigolds, and if so, which ones? And is there a right way to grow marigolds?
Let’s explore this fascinating species of flower in depth and go over everything you need to know to grow them properly!
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- Safer Brand Insecticidal Soap
- Neem Bliss 100% Cold Pressed Neem Oil
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- Monterey BT Caterpillar Killer (Bacillus thuringiensis)
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- Safer Brand Garden Fungicide
|Common Name||Marigold, African marigolds, Aztec marigold, American marigold, French marigolds, signet marigolds, golden marigold, Mexican marigold, Mexican mint marigold, Texas tarragon, Mexican tarragon, Spanish tarragon, sweetscented marigold, sweet mace, pericon, yerbaniz, hierbanis, wild marigold, huacatay, southern marigold, stinking roger, black mint, khakibos, pot marigold, and many other common names depending on additional species|
|Scientific Name||Tagetes erecta, Tagetes patula, Tagetes tenuifolia, Tagetes lucida, Tagetes minuta, Tagetes lemmonii, Tagetes palmeri, Calendula officinalis, and another 49 species of marigolds, some Tagetes species, and others not|
|Light||Full sun but will tolerate partial afternoon shade|
|Soil||Well-draining, but can tolerate many types of soil and multiple pH levels|
|Water||Water only when soil has dried out, about once weekly or more during hot weather|
|Pests||Aphids, spider mites, leafhoppers, tarnished plant bugs, slugs, snails, and a variety of caterpillars, including the cabbage looper, beet armyworm, and tobacco budworm|
|Diseases||Powdery mildew, leaf spot, botrytis cinerea, fusarium, phytophthora root/stem/crown rots, aster yellows, cucumber mosaic virus|
All About Marigolds
Covering about 56 species, the marigolds or Tagetes are extremely popular plants. Many species, such as Tagetes tenuifolia, Tagetes lucida, and Tagetes minuta, have edible flowers and offer a spicy-citrus or mintlike flavor to an assortment of dishes. The ever popular Calendula officinalis (pot marigold) is also considered a marigold. The flowers of Tagetes erecta are known for their tall, upright nature.
While many contemporary hybrids are scentless, the ones that do have a scent are often compared to the smell of wet hay or straw. That scent is reputed to drive away Mexican bean beetles and other beetles, squash bugs and leafhoppers, and even tomato hornworms.
Whether or not it works, what definitely does work is when people plant marigolds to help keep pestilent nematodes at bay. A naturally-forming compound in marigold roots will eliminate root-knot nematodes in the area where it’s planted.
The scent of marigolds is also rooted deep in tradition. That aroma, along with the vibrant color, is believed to guide spirits of the dead back to their families during Dia de Los Muertos, the Mexican day of the dead. They are used to decorate the altars or ofrendas of family members.
In fact, it’s such a popular flower during that time of year that it’s referred to as the flower of the dead. Pixar animated millions of tiny marigold petals in their film “Coco” to create the bridges over which the spirits come, and marigolds can be found throughout the film.
So whether you’re planting marigolds to wipe out pests, to provide vibrant yellow and orange petals to top your salad, to draw the memories of your families close, or just for a pop of color in the garden, there’s a lot of history behind this simple little flower!
Types Of Marigolds
There’s no reasonable way to cover all species of marigolds in one short piece, so let’s go over some of the most popular species. There are individual cultivars and hybrids of these species available too, but this will give you at least a glimpse of some of what’s out there!
Tagetes erecta, ‘African Marigold’, ‘Aztec Marigold’, ‘American Marigold’
Native to Mexico, the large flowers of African marigolds (Tagetes erecta) have traveled far and wide. The African marigold was introduced to southern Europe from North African peoples who traveled across the Mediterranean. However, the double flowers of African marigolds are native to South America. Thomas Jefferson planted African marigold seeds on his Winding Flower Walk, which occurred in 1812. This was one avenue for the rising popularity of African marigold in America.
One of the larger-growing species of marigold, the Aztec marigold grows to heights of 20-35 inches tall and wide and produces an abundance of vibrantly-colored marigold flowers. Its flowers are edible, its roots eliminate nematode populations, and it is a source of many natural dyes.
This variety of yellow and orange marigold is most commonly known as the flor de muertos, or flower of the dead, and is often grown in cemeteries. You’ll often see African marigolds grown alongside tomatoes for pest control purposes.
Tagetes patula, ‘French Marigold’
Rarely growing to much taller than a foot, French marigolds also originate in Mexico. Much more potently scented than the Aztec marigold, French marigolds are often the species grown as an aromatic pest repellent. Their roots also secrete natural nematode-killers.
When in flower, the whole plant of French marigolds is distilled for its essential oil, which is used to create a type of perfume called attar genda. The marigold flowers themselves are edible and are often ground into a spice blend. French marigolds can also be used to create natural dyes.
Tagetes tenuifolia, ‘Signet Marigolds’, ‘Golden Marigold’
Originating in the area from Mexico down well into South America, signet marigolds are often cultivated to act as a mosquito repellent due to their powerful, hay-like scent. Signet marigolds have flat flowers unlike both the French marigolds and African marigolds and their puffier flowers. They are more like some varieties of Calendula officinalis (pot marigold).
Golden marigolds or signet marigolds grow to reach 10-20 inches tall and can spread almost invasively if they’re not well maintained. These also produce edible flowers, which are often used directly on salads when fresh or added to spice blends when dried.
Tagetes lucida, ‘Mexican Marigold’, ‘Mexican Mint Marigold’, ‘Texas Tarragon’, ‘Mexican Tarragon’, ‘Spanish Tarragon’, ‘Sweetscented Marigold’, ‘Sweet Mace’, ‘Pericon’, ‘Yerbaniz’, ‘Hierbanis’
While it’s got a ridiculous number of names, Tagetes lucida is likely known best as a spice. Its lightly anise-flavored petals are used to brew teas in Mexico and through parts of Central America from where it originates, and it is often used as a tarragon substitute.
Some species are bushier than others, and this marigold variant grows to reach 18-30 inches tall. It is a form of wild marigold, but is beginning to be cultivated as extracts from the plant are showing to be medicinally viable in lab studies.
Tagetes minuta, ‘Wild Marigold’, ‘Huacatay’, ‘Southern Marigold’, ‘Stinking Roger’, ‘Black Mint’, ‘Khakibos’
The ‘minuta’ in this plant’s name definitely does not apply to the marigold plant, which is anything but minute! This extremely large plant can grow to heights ranging from 2-6 feet tall. However, its marigold flowers are extremely diminutive, lending it its name.
Unlike other marigold species, the wild marigold’s leaves are edible rather than the flowers. They’re often dried as a seasoning or made into a paste which is called black mint paste. The plant’s oils are distilled as marigold oil and used in multiple different industries.
The flavor of the leaves is a mix of basil, tarragon, mint, and citrus and is popular when used to season ocopa, a Peruvian dish made from potatoes.
Caring For Marigolds
With the exception of some light watering and regular deadheading of spent yellow and orange marigold flowers, care for marigolds is extremely easy. In fact, children can grow marigolds in science experiments! For optimal growing, skim through the next few sections for tips.
Light and Temperature
Marigolds prefer full sun conditions to create those vibrant flowers. However, they will tolerate partial afternoon shade if that’s what’s available. Aim for at least 6 hours of good sunlight a day for best growth.
While many plants are very zone-specific, marigolds aren’t. They will readily grow in zones 2-11, making them one of the widest-ranging marigold flowers available. However, most species are not frost-tolerant, and the marigold plant will die back once cold weather arrives. Therefore only plant them after the last frost date.
There are a few perennial versions of marigolds, but the majority are annuals, so once the plant dies back in the fall, it can easily be turned under to add quality organic material to the soil.
Water and Humidity
While marigolds can handle the heat, they have some problems with humidity. It’s important in your methods of care for marigolds to only water marigolds at the base of the plant, as powdery mildew is a very real risk on its foliage when wet. Also, good airflow is a must, especially in more humid conditions.
Allowing the soil to somewhat dry out between the times you water marigolds is recommended, but when you do water, water well and deeply to provide ample moisture. More water will be needed in hot weather because while the plants thrive in the sunlight, they still need a refreshing drink.
Your marigolds can handle nearly any soil type or pH level. They’re not very picky plants in the wild, and the same holds true in your garden. However, a sand or loam mixture with lots of organic matter is best, as clay-type soils can cause drainage issues or promote root rot. Most ordinary commercial potting soil mixes will suffice!
You don’t want too rich of a soil, either. Marigolds are not heavy feeders, and in fact, too rich of a soil can actually cause your plant to explode into growth and barely flower at all. Something which is less nutrient-dense is actually great for marigolds.
No matter which soil type you opt for, whether it be amended native soil or ordinary commercial potting soil, be sure that it’s well-draining. If you need to add perlite or other drainage aids, do it. If the soil holds too much water, you’re risking damage to the roots of your plants.
It’s recommended to mulch around the base of your plants, especially if you’re in a hot climate. Not only will this prevent weed spread, but it will help keep soil moisture regulated.
Since most varieties of marigolds are annuals, you don’t need to fertilize repeatedly throughout the season. A good dose of balanced diluted liquid fertilizer and some rich compost blended into your soil before planting is all you need.
I don’t fertilize marigolds during the plant’s growing cycle. Too much fertilization with diluted liquid fertilizer will cause your plant to just try to grow and expand more, and it won’t devote much energy to flowering. For the best blooms, stick with pre-planting fertilization only!
Your plants themselves can become fertilizer for next year’s planting. When they’ve started to die back in the fall, till them under the soil to allow them to break down over the winter months. This adds valuable plant matter and nutrients back to the soil. So no need to add much to fertilize marigolds.
The easiest way to propagate marigolds is from seed, as they germinate extremely well. However, you can also pot marigolds to propagate from cuttings.
To propagate from seed, you can either opt to intentionally plant in containers, or you can broadcast seed onto a prepared bed.
If you are planting into a container (such as a small pot to transplant from later), place 1-3 marigold seeds per pot and thin to the healthiest plant. For broadcasting, try to have about a 2″ spacing between seeded plants, and then thin down to 1 plant every 8-10 inches at most (and 12″ is better).
From cuttings, you will need to examine your existing plant thoroughly. Select stems which have not flowered and that are longer than 4″. Remove all leaves except for the 2-3 at the top of the cutting.
Dip your cutting into water and then into rooting hormone. Place it into a prepared container of your preferred rooting medium, and do not place more than 2″ under the soil’s surface. I find that a mix of even parts of peat, perlite, and sand works very well for rooting marigolds.
You’ll need to keep the humidity up around your pot marigolds as they form roots. I water my cuttings well and then place them inside a plastic bag with a stick inside to keep the bag from collapsing down onto the cutting, using a rubber band around the pot to create a greenhouse-like effect.
Check every 3-4 days to make sure the soil stays moist, and place it in a warm, bright area but out of direct sunlight. It should take 2-3 weeks for your cuttings to take root, after which you can harden them off to the outdoor conditions gradually.
Saving Marigold Seeds
One thing that marigolds do extremely well is to create new seeds within the flower. These don’t produce a separate seed pod, it all happens directly inside the blossom!
When the flowers of your African marigolds or signet marigolds start to fade, you can deadhead the spent flowers and lay the heads on a drying tray in a dark location. Allow them to dry out completely – this usually takes about a week. Once dry, you can remove the flower petals and extract the small black marigold seeds from inside.
Alternately, you can place a paper bag over the flower head, securing it with a rubber band, and then clip off the spent flower. Let it dry completely, and then push the dried flower and its stem down into the bag. Close it securely and shake vigorously to release the marigold seeds.
Hybrid marigolds may not produce an identical match to their parent plant. Similarly, if you’re growing a variety of marigolds, cross-pollination may change the type of plants your marigold seeds will produce. This works best if you’re growing all the same variety.
Before you plant marigolds, prepare your soil in advance. If you plan to plant seedlings outdoors directly into a bed, it’s good to cultivate your soil to a depth of about 8″ to loosen it up. Do any amendments you want to add at this time, including slow-release fertilizers or the addition of compost.
Also, before you plant seedlings outdoors, thoroughly water your marigolds the night before to ensure their roots are plump and full of water and that the plant is well-hydrated. This will help to lessen transplant shock.
Remove your pot marigolds from their existing container and gently open up the root ball with your fingertips. Plant marigolds in your prepared soil at the depth at which it was originally planted in, directing the roots out from the root ball.
If you are transplanting into pots, don’t crowd them. A 12″ pot should have no more than 2-3 small plants to ensure there’s enough airflow around them. Less is more, as your marigolds will grow in size!
Newly-planted marigolds should be allowed time to get established. It’s best to ensure young plants have 2-3 weeks before you do much to them. After that, you can pinch out the tips of new growth early on to encourage a bushier growing habit.
Let’s talk about deadheading marigolds. Deadheading your spent marigold flowers regularly encourages your plant to bloom again. With consistent deadheading, you can have a riot of color all summer and well into the fall!
If your marigolds have become leggy or aren’t producing enough flowers, or are stuck with early flower buds, you can cut back up to a third of the plant midseason. This will encourage a burst of new growth as well as new blooming. Try to cut about a quarter-inch above a leaf bud whenever possible.
You can trim off individual leggy stems to maintain your plant’s shape at any time (even on young plants), but again, try to cut just above a leaf bud so your plant can continue to bush outward.
Perennial marigold growers should do an annual cut-back of their plant. This can occur in the fall once the plant has stopped blooming or early in the spring before it begins to develop new growth. Remove 2/3rds of the plant at this time, as it allows for new growth to form easily.
You’re probably thinking right about now “but marigolds prevent pests, why would they have any problems?”
Well, unfortunately, there are some pests that find marigolds to be absolutely delicious. There are also a few diseases that might cause you some trouble. So let’s go over a list of the problems that may arise, and that way, you’ll be prepared in case they do!
Marigold Growing Problems
Are your plants exhibiting lots of foliage growth but very few marigold flowers? It’s likely the fault of too much fertilizer. It’s best to fertilize the soil just before planting your French marigolds, African marigolds, or Signet marigolds. Avoid fertilizing mid-season.
If your plants aren’t flowering at all, check the weather report. If it’s too hot, marigolds will devote their energy to staying alive, not producing pretty blossoms. Use 2-3″ of mulch around the base of your plants to lower the soil temperature. In the heat, make sure to water marigolds adequately.
Are your marigold flowers fading? If there are drastic temperature fluctuations from hot to cold, marigold flowers can become pale. This is especially prominent in the darker-colored French marigolds and African marigolds but can happen to any type. This fixes itself once the weather calms down.
Aphids aren’t going to choose marigolds over other preferred targets, but if their preferred food isn’t available, they can attack. This causes curled or distorted leaves on your plants. While it’s mostly cosmetic, aphids carry diseases, so use insecticidal soap or neem oil to repel them.
Spider mites can cause stippled marks on leaves and discoloration. They also create super-fine webs which build up on the plant’s surface and are common in dry conditions. Use some neem oil to kill these pests off.
Leafhoppers can also cause distorted or discolored leaves, plus they spread diseases like aster yellows. Thankfully, insecticidal soap or neem oil will keep these at bay, too.
Plant bugs, especially tarnished plant bug, can cause dwarfed or deformed flowers. An insecticidal soap with pyrethrin will wipe these irritating pests out.
Slugs and snails find marigolds absolutely delicious, and will mow down your plant if left to their own devices. An organic granular bait will distract them from the plants and will knock down the population.
Finally, a bunch of caterpillars can nibble on the flowers or foliage of your marigolds. The beet armyworm, cabbage looper, tobacco budworm, and a few others can create holes in the flowers or leaves, or chew lines down the edge of the leaves. Use a BT spray to wipe these out.
If you plant marigolds as a trap crop, allow the pests to take their toll on the plant in the growing season, and then take the entire thing out and dispose of it in the trash.
Marigolds are stubbornly resistant to a lot of the treatable disease types. Unfortunately, this means that if they contract a disease, it’s likely to be a major problem.
Among the treatable diseases which marigolds can get is powdery mildew. This will cause a whitish powdery substance to appear on the leaves. It’s usually a sign of too much moisture on the leaves.
Keeping your plant’s leaves dry and watering below the foliage will prevent powdery mildew from forming in most situations. If your marigolds do develop powdery mildew, a few treatments with neem oil should eliminate the problem.
A variety of leaf spots strike African marigolds, but the French marigolds are usually immune. These cause black spots and spores to appear on the leaves, and if not treated quickly can very rapidly spread (especially if the plants are damp).
Remove damaged leaves before the spores have time to spread. Applying a liquid copper fungicide may wipe out the spores. If it doesn’t work and the plant gets worse, dig up and dispose of both the plant and its surrounding soil. Don’t compost these, the spores can survive in the compost!
Botrytis cinerea can cause grey spots to form on the leaves. You may be able to remove the affected parts of your plant and throw them away, then sterilize your tools thoroughly. Again, don’t compost these. However, if the problem is severe, remove and throw out the plant.
Unfortunately, there are a number of plant diseases that aren’t treatable. Let’s go over those now.
If your seedling plants are damping off/falling over, or your adult plant is stunted and turns yellow, you are fighting against fusarium. There’s no real cure for plants which are already infected with this disease, so you’ll need to remove and destroy them.
Phytophthora root, stem, or crown rots can cause your African marigolds to develop dark lesions on the stem or mushy roots beneath the soil. These will gradually worsen and kill off your plant. Most French marigolds seem to be less susceptible to this problem.
Remove plants suffering from these rots and their surrounding soil. Destroy or throw them away, don’t try to compost them. Lighten the future soil with perlite to reduce the moisture content.
Aster yellows is spread by leafhoppers and aphids. This condition can cause the flowers or entire plant to turn yellowish-green and become deformed. It may also develop spindly, weak shoots.
Pull up plants which show signs of aster yellows and destroy them, don’t compost them. Spray your other healthy plants with a sulfur fungicide to avoid further spread, and get rid of the pests that spread it.
Finally, the cucumber mosaic virus can be transmitted by aphids as well. While it’s fairly uncommon in marigolds, it can occur, and it causes plant stunting, discoloration and distortion of leaves. Again, remove and dispose of the plant, and get rid of the aphids!
Frequently Asked Questions
Q: Are there purple marigolds or blue marigolds?
A: Sadly, no. If you cruise around on the internet, there’s a plentiful amount of people who claim to have these, but marigolds do not actually produce blues and purples.
You can find marigolds in shades ranging from off-white or ivory through deep reds, with all yellow and orange colors in between. But usually, the seeds sold as blue marigold or purple marigold seeds online are actually chrysanthemums or just a scam, so avoid them entirely!
Q: Are marigolds annuals or perennials?
A: Most marigolds are annuals. As far as perennials go, look at Tagetes lucida (Mexican marigolds), Tagetes lemmonii (Lemmon’s marigold), or Tagetes palmeri (mountain marigold).
Before you rush to plant these perennial varieties, be aware that even these don’t tolerate frost conditions well. If you’re in a region where you get frost, you’ll need to either cover your plants with a cold frame before the last frost date and possibly heat it, or you’ll want to bring them inside under grow lights. Or just be happy with the annual presence of French marigolds.
Q: Do marigolds take sun or shade?
A: Marigolds absolutely love full sun. Give them lots of light to keep them happy. This is one of the essential aspects of care for marigolds.
Q: What do marigolds keep away?
A: They don’t actually keep away most insect pests (save root-knot nematodes). Above-ground pests see the plant as a food source. Therefore, they are a great trap crop for spider mites, aphids, and thrips. They also keep out curious mammals who may see your garden as a food source or dumping ground.
Q: When should you plant marigolds?
A: Plant them in ordinary commercial potting soil in spring after the last frost date has passed. This will give them time to get established before the cold arrives.
Q: How long will marigolds last?
A: Most marigolds are annuals, and grow, bloom, and die in the span of a year. Some are perennial and live for multiple years.
Q: What month do marigolds bloom?
A: One of the best things about marigolds is their long blooming period, which lasts from May to September in their hardiness zones. This is one of the chief reasons people grow marigolds.
Q: Do you deadhead marigolds?
A: Yes! See the Pruning section of this piece for more details. You can deadhead spent flowers or cut them back midseason.
Q: What animals do not like marigolds?
A: Rats and rabbits are deterred by them. You can grow marigolds in a border around your annual crops to keep these smaller rodents out.