Marigolds have a reputation for being one of the easiest flowers to grow. They’re often the first plant children get to care for and require very little upkeep.
But growing marigold flowers aren’t without their problems, especially when many of our favorite plants aren’t part of the marigold genus (Tagetes spp.).
One of the most common problems you might face is the marigold failing to bloom.
Why does this happen, and how can the problem be fixed?
Why Marigolds Do Not Bloom?
There are several reasons your marigolds may be unable to bloom, many of which are easily fixed.
Here are the most common reasons and how to fix them.
This is one of the most common reasons a marigold will fail to bloom, yet it’s also perhaps the easiest to avoid.
Marigolds have a shallow root system and will need to be watered fairly often compared to most of your other plants.
However, this doesn’t mean using a calendar for watering is okay.
Instead, you should always employ the soak and dry method, and you can use the finger technique to know when it’s time to water.
To use the finger trick, simply stick your finger into the soil and water if it’s dry ½” inch down (approximately halfway from your fingertip to the first knuckle).
One other thing to keep in mind is the soil consistency.
Even if you’re using good watering habits, a marigold may have trouble drinking or can get waterlogged if the soil is too compact.
Adding some perlite or vermiculite to the soil before planting can help keep things loose and well-draining.
If you’re reduced to clay soils in the garden, try purchasing and mixing in some topsoil and perlite to give it a better consistency so water can drain out easier.
Infection And Infestation
While often discussed separately, plant disease almost always goes hand-in-hand with infestations.
Piercing insects such as aphids, mealybugs, and scale drink the sap from your plant’s leaves.
Their frass (poop) is known as honeydew and consists of partially digested (or even undigested) plant sap.
This honeydew is a perfect breeding ground for several fungal infections that affect marigolds, especially powdery mildew.
Meanwhile, root rot and fungal infections caused by overwatering can attract fungus gnats and other pests that either feed on the fungus during part of their life or are attracted to the weakened plant.
Both infestations and infections can weaken a plant to the point it can no longer produce blooms.
Dealing with an infection or infestation can be difficult, but neem products are a great alternative to chemical remedies.
Neem oil is also known to help fight some fungal and bacterial infections.
For surface issues, a neem foliar spray can be quite effective.
Meanwhile, neem soil soaks can defend against internal infections, combat some forms of root rot, and kill piercing insects as they feed.
Neem can greatly reduce the risk of infestations and many types of infection when used proactively alongside proper care methods.
Too much of a good thing is never good; this is especially true of fertilizer.
Fertilizers are meant to augment or make up for nature’s natural practice of replenishing the nutrients in the soil.
Adding too much fertilizer to the soil around your marigolds may sound like a great way to boost blooms, but it can actually make the soil toxic.
Not only can fertilizer cause chemical burns to the plant and its roots, but it can also create an excess of mineral salts in the soil.
The good news is that you can flush a potted marigold to eliminate the excess fertilizer.
However, for ground-based plants, you may need to temporarily uproot them and blend some fresh topsoil into the overfertilized soil to dilute it.
Sunlight is essential for healthy blooms, and it’s easy to deprive your marigolds of adequate lighting, especially if growing indoors.
For a happy and healthy marigold, you’ll need to ensure the plant gets at least 6 hours of full sun per day.
Anything less than that and your marigold will likely fail to bloom – even if it still has green foliage.
Sometimes the problem isn’t that a marigold won’t produce any blooms. Instead, it’s that it fails to create new blooms after a wave has been spent.
When a bloom dies, it draws resources from the plant until it falls off.
Likewise, plants often don’t feel the need to produce new blooms as long as the old ones are still attached.
A popular remedy for this problem is known as deadheading.
You can use shears or even your own fingers to deadhead.
Simply remove any spent blooms occasionally, and your marigolds will be encouraged to produce more.
Temperature And Humidity
One of the great benefits of growing plants indoors is the ability to control the climate in any particular room.
Unfortunately, we don’t have that same amount of control outdoors.
Marigolds can fail to bloom if there’s a high humidity level (including too much rain), as they don’t like any excess moisture.
Likewise, when temperatures drop below 70° degrees Fahrenheit or go above 90° degrees Fahrenheit (some species can handle slightly higher temperatures), marigolds will be unable to produce blooms and may lose any existing flowers.
Obviously, this is sometimes unavoidable, but you can help reduce the impact of heat and rain by providing some light cover during midday or when there’s a lot of rain.
Finally, let’s look at one of the simplest (yet also the most easily overlooked) reasons your marigolds might not be blooming: the timing.
While marigolds tend to bloom between late spring and early fall, this doesn’t mean they all bloom simultaneously.
For example, the French marigold (Tagetes patula) is an early bloomer, bearing its flowers approximately 8 weeks after planting.
On the other end of the spectrum, the Mexican marigold (Tagetes lucida) doesn’t bloom until late summer.
So before you panic, consider what species you have (or what species your cultivar comes from) and whether or not it’s due to bloom yet.