11 Reasons Your Begonias Aren’t Blooming and How to Fix it
Do you have begonias in your garden this season that just won't seem to bloom? There are actually several reasons why this may happen. In this article, certified master gardener Laura Elsner walks through the primary reasons begonias may struggle to bloom, and how to fix it when it happens.
Begonias in full bloom are one of my favorite sights in summer gardens. These shade-loving flowers produce blooms in all sorts of sizes and colors. Begonias are generally easy to care for, and some varieties actually make great houseplants.
But when they are not growing in their ideal conditions, begonias will stop blooming. There are a few common reasons this happens, and the good news is that most of the causes are treatable if caught early on.
So, if your begonias aren’t blooming this season like you’d expect, with some adjustments you should be able to get them showing off their beautiful flowers again soon. Let’s take a look at the most common reasons your begonia may not be blooming, and how you can both prevent or fix the problem!
You Picked The Wrong Variety
I am going to get this one out of the way first. While all begonias bloom, many varieties are not known for their blossoms. The rhizomatous varieties are known for their beautiful foliage.
This includes the very popular rex begonia varieties. These varieties might put out a few stalks of small white flowers, but they are not the large rosettes of blossoms that tuberous varieties have.
Check your variety and make sure they are a blooming variety. Chances are if the foliage is very colorful, the blossoms are not going to be spectacular.
You’ve Been Watering Too Much
Begonias have tuberous stems that hold on to water. They are very sensitive to overwatering. They become a floppy droopy mess when they get too much water. It will also cause all the blossoms to drop off.
To correct this, check the soil and make sure it is evenly moist but not wet. If it is soggy, quit watering immediately. Let the soil dry out.
If your begonias are in a container, make sure the container has drainage holes in the bottom. Also use a potting mix for soil, not black earth or garden soil. This will help the soil absorb and drain moisture so the container doesn’t get too soggy.
For garden begonias, make sure to amend the soil with plenty of coir or peat to make the soil able to retain water and drain the excess. If you take a handful of your soil and squeeze in your hand, if it stays in a ball of putty, it needs to be amended with coir or peat.
It should just crumble away after the soil is squeezed. You might have some naturally boggy areas in your garden, this is not a suitable location to plant them. They do not tolerate being in standing water.
Too Much Sunlight
Begonias are shade-loving perennial plants, too much sun and they will burn up and not bloom.
If the leaves are crispy and the plant is stunted, take a look at the amount of sun they are getting. Shade plants like 4-6 hours of direct sun. I find early morning sun or late afternoon sun is best. The strong mid afternoon sun can burn them and they won’t bloom.
There are some begonia varieties that can take more sun. The Cocktail series of wax begonias features dark bronze leaves that can tolerate more sun than the regular green leaf varieties.
There is also the Solenia series of tuberous begonias that can take more sun than other varieties. Choose these for planting in sunnier areas.
You Haven’t Watered Enough
I think over watering begonias is far more detrimental to begonias than under watering them. But there is a point where begonias will shrivel and shrink and cease to bloom if they are too dry.
Soil should feel evenly moist. Not bone dry, and not soggy wet. The easiest way to check is to just sink your finger into the soil.
If it feels dry add water if it is still moist, leave them be. I would check daily and then eventually you will find a pattern and can stick to a watering schedule that works.
Not Enough Sunlight
While begonias are known as shade flowers, they actually need some direct sun in order to get blooms. Deep shady pockets of the garden are not a suitable location for blooming varieties.
4-6 hours of sun in the morning is ideal. If you do have a very shady area in your garden try a non-blooming variety of begonia. Rex begonias have intricate foliage colors and patterns and unremarkable blooms. They brighten up the shade with no blossoms at all.
You Used The Wrong Soil
Begonias like light soil filled with lots of organic matter. They do not like heavy clay soils and soil with little to no nutrients. If you get the soil right, you will have lovely blooms all season.
For begonias in containers, stick with a potting mix. This is light and fluffy and the perfect growing medium.
For garden begonias get your garden soil light and fluffy. Consider mixing in peat or coir and some compost, seas soil, worm castings, or manure to your garden beds before planting. This will ensure a nice light soil for them to thrive and bloom in.
You Skipped Deadheading
Deadheading is the process of removing dead or dying flowers from plants. This will trigger the plant to create more blooms. For begonias I trim the flower stalk down to the nearest larger stem.
The begonia will shoot out more blossoms once the old ones are removed. The more you pick the old blossoms the more new blossoms you will get.
You Don’t Fertilize
The secret sauce to flowering annuals is fertilizer. I fertilize once every 10-14 days. I use a water-soluble 20-20-20 blend and water my begonias with it.
This will really pump up the blooms. Especially for begonias in containers, they use up the soil nutrients quickly in a container environment.
Make sure to water your plants before fertilizing. Fertilizing dry plants can burn the plant.
You’ve Over Fertilized
Ok, so fertilizer is good, so why not use more? Too much fertilizer can be detrimental to plants and flowers.
You can end up with lots of leaves and leggy growth but no blooms. Or you can even burn a plant with too much fertilizer. Stick to fertilizing one every 10-14 days.
Don’t fertilize newly planted begonias, give them a week or more to establish roots.
You Have a Pest Problem
Check for pests if you are finding less blooms. If you see sticky leaves and they are covered in a filmy web, it is spider mites. Spider mites envelope the leaves and blossoms of begonias and they will stop blooming and eventually succumb to the infestation if it is not treated.
Healthy begonias are less likely to be affected by pests. Keep them in their ideal sun and soil conditions, and keep them evenly moist. But if you are already dealing with a spider mite infestation the best thing to do is to get an insecticidal soap spray and spray according to the package directions.
I have seen spider mite infestations that are so bad that sometimes I will just pull the plants and start again.
Begonias can also be infested with mealybugs or aphids. Treat the same as spider mites. Prevention first, then treat with insecticidal soap. For mealybugs, you can also use a cotton swab in rubbing alcohol and dab it directly on the mealybugs.
Again, if the infestation gets really bad it might be time to pull them out and cut your losses before they spread to neighboring plants.
You Have Powdery Mildew
Begonias are particularly susceptible to powdery mildew. They like shady moist conditions and so does powdery mildew. If you notice a white powdery substance on your begonias that can be wiped clean, chances are this is the problem.
Begonias will struggle and cease to bloom when struggling with a battle against powdery mildew. Keeping them in their ideal growing conditions will help reduce mildew. Also, avoid watering in the evening and spraying water directly on the foliage.
Leaving the leaves wet overnight is a breeding ground for powdery mildew. If you have mildew on your plant there are a variety of fungicides available at garden centers, and there are more environmentally friendly DIY solutions.
Begonias are beautiful blooming plants. When they are healthy and in the right conditions they will bloom continuously all season long. If they aren’t blooming take a look at these 11 tips and see if you can figure out the reason they aren’t blooming. Once you correct the problem they should go back to blooming.