Only a few flowers evoke the spirit of autumn like Chrysanthemums do! Or, as we simply call them, mums.
Mums start to bloom during the late summer through fall, making them perfect “filler flowers” for those empty spots after the summer flowers fade.
One thing to know about these flowers is that they bloom profusely, so if they aren’t blooming, something is definitely wrong.
Mums stop blooming if they get less than six hours of direct sunlight a day or if they don’t get enough water. Underwatering or soggy soil can cause pests, diseases, and root rot, all of which can cause stunted growth.
Lastly, forgetting to pinch mums during spring can also stop them from blooming.
These flowers are hardy, fast-growing herbaceous perennials that typically produce flowers during their first growing season from early September to mid-October. However, if cared for incorrectly, they may stop blooming altogether.
So, let’s find out what’s the culprit behind your mums not blooming.
Why Are My Mums Not Blooming?
We all love the feeling of anticipation waiting for that colorful flower to bloom in the spring! So, imagine the disappointment when fall comes around without a single bloom appearing.
Because of their hardy nature and easy-care requirements, it’s often baffling when mums fail to bloom, and you can be certain there’s a good reason for it.
The most common reasons that prevent garden mums from blooming include:
- Insufficient lighting
- Incorrect watering
- Waterlogged soil
- Pests and diseases
- Forgetting to pinch them after blooming
1 – Faulty Lighting
1 – Faulty Lighting
Garden mums typically thrive in full sunlight, but they can tolerate a bit of shade. However, despite their tolerance for partial shade, receiving insufficient sunlight daily can stop them from blooming.
These flowers should get at least six hours of bright direct sunlight daily to ensure that they stay healthy and continue blooming.
More so, garden mums are “photoperiodic” plants, meaning that they bloom abundantly during shorter days and longer evenings.
They’re pretty sensitive to day length and light exposure, so you’ll want to avoid exposing them to bright nighttime lighting because it can mess with their cycle.
2 – Incorrect Watering
Garden mums enjoy evenly moist soil; they require around one inch of water weekly during their growing season (late summer through fall).
Once the flower buds mature and open, the flowers will need more water, so the soil will dry out faster. A dried out soil can cause the blooms to drop and fall off, so you’ll want to ensure it stays moist all the time.
At the same time, it’s important to maintain a balance. Overwatering your mums can also impact their blooms because it causes soggy soil, which leads to root rot, pests, and diseases that inhibit flowering.
3 – Waterlogged Soil
While mums accept various soil types, they thrive in rich, slightly acidic soil with good drainage.
Poor soil drainage can cause the plants to rot and stop flowering as they sit in standing water. So, you’ll want to steer clear of overly dense and clay-like soil.
If you plant your garden mums in pots, make sure that they have drainage holes to prevent the plants from sitting in waterlogged soil.
4 – Pests and Diseases
Garden mums are susceptible to common pests and diseases, which can cause stunted growth if not treated right away.
During the fall, there’s a higher chance of these diseases because the weather becomes wet, which invites mold spores and fungal diseases.
The primary signs of these diseases typically appear on the leaves or buds first. Once you notice them, consider using an antifungal spray to treat the plant. You’ll also want to remove the infected stems to prevent the fungus from spreading.
However, it’s important to first identify the pest you’re dealing with.
The most common diseases that affect mums include leaf spot, botrytis, rust, powdery mildew, and stem and root rot. As for the pests, they can range from aphids and thrips to lace bugs and leaf miners.
If your garden mums’ flower buds turn brown, treat the plant with a Bordeaux mixture, as the infected buds are unlikely to open once the tips go soft and turn brown.
Meanwhile, if your mums’ leaves are wilting and you are confident that it’s not from overwatering, it can be verticillium wilt (a fungus).
Unfortunately, the only solution is removing the infected parts of the plant.
After that, avoid planting mums in the exact location as they will likely contract the same soil fungus again.
5 – Forgetting to Pinch Mums
Pinching back mums is a common practice of removing two to three inches of the growing tips of the plant using a sterilized pruning shear.
Doing this supposedly encourages new growth by forcing side branches to form, which can later develop new buds and flowers. However, it’s critical to pinch the flowers early in the season to allow blooming before the frosty weather sets in.
Ideally, you should pinch back mums in the spring when they reach around 10 inches high.
If you recently purchased the flowers, wait for two weeks after you plant them to pinch off the branches. Then, pinch again time during the summer solstice when the days start to shorten after the longest day of the year.
Remember that pinching your mums after July will only remove the buds and reduce blooming. So, wait for them to flower, and once the flowers wilt, chop the dead tips off.
6 – Overcrowding the Flowers
Overcrowding any plants causes them to compete for basic nutrients, like soil nutrients and light. So, if you’re planting all the mums in one flower bed without enough distance between them, that could be the reason they’re not blooming.
They may be keeping the shade from reaching each other, or they’re simply taking up all the soil nutrients, leaving nothing for the weaker flowers.
Some flowers will either stop blooming altogether or grow weaker blooms. So, make sure to leave a distance of at least 18 inches between each flower and its neighbor.
7 – Over-Fertilizing
A lot of people make the mistake of fertilizing their mums after they form flower buds. You should only fertilize the mums using a nitrogen fertilizer when their leaves are still growing, which often happens in the spring.
Fertilizing after the flower buds form can be unnecessary and may have adverse effects. If you want to fertilize the flowers during the fall, opt for a high-phosphorus fertilizer, and don’t use it excessively.
Chrysanthemums start showing their joyful blooms from late summer through fall. So, when your garden mums aren’t flowering, the main culprit is probably insufficient light, incorrect watering, or high soil density.
Common pests and diseases may also weaken the plant, leading to fewer blooms.
Pinching your mums encourages them to develop new shoots and buds, increasing the number of their flowers throughout their growing season. So, don’t forget to do it once the days begin to shorten!
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.