Why Are My Begonias Dying? | + 5 Steps to revive them

Begonias are a hardy plant and they can be grown inside or out in the right conditions. They can die if they are overwatered, underwatered, are attacked by aphids, or suffer from mold or bacterial leaf spot. There are some easy steps to follow to give your begonia the best chance of recovery including correct watering, slow release fertilizer and trimming.

This article will explore the top 7 reasons why begonias could be dying and the 5 steps to follow to give them the best chance of recovery.

Top 7 reasons why begonias could die

Here are the top reasons in my experience that begonias wilt, dry and eventually die.

1. Not enough water

Begonias are drought tolerant but going too far can cause them to wilt and eventually die. You will notice browning, dry leaves and eventually the stems will bend over.

2. Too much sun

Too much sun can cause the begonia to brown, wilt and die. Begonias don’t like direct hot sunlight particularly if you live in a hot, dry area. Begonias are naturally popping up in areas of my garden where they were previously grown and they are growing best in the shade.

These begonias are popping up next to my golden cane palms and near a downpipe on the side of the pipe.

3. Too much water

Begonias hate being overwatered. It is important to allow them to dry out between watering so that they don’t suffer from root rot or stem rot. When water is splashed all over the leaves, they can develop bacterial or fungal growth which can eventually kill them off.

I had placed a begonia cutting into a jar of water to see if it would sprout. Instead it quickly grew white mold, then black and wilted over and died. Begonia cuttings can be grown in potting soil but for me, the excess water in a jar cause it to rot and die quickly.

4. Root rot

Tuberous begonias are more susceptible to root rot. Make sure when you plant begonias that you don’t bury the stems too deep. They are soft and will absorb water quicky and can rot. This will cause the plant to die off slowly, usually starting with yellow and brown marks and the plant can die quickly.

5. Bacterial leafspot

Bacterial leafspot can be a problem that affects begonias at home inside or outside. It is caused by a bacteria called Xanthomonas axonopodis pv.begonia¹. The leaves will look damp and you will see dark black or brown spots under the leaves. The leaves will eventually fall off and land under the plant.

The leafspot can be spread to other begonias as water splashes from one plant to the other. Removing the affected plant is the best way to be sure that it doesn’t get to your other begonias nearby.

If it is affecting one area of the plant. Cut it off and throw it in the bin so it doesn’t get into other areas of your garden. Do not put the leaves into your compost or worm farm.

Avoid watering the begonia overhead as this will cause the bacteria to grow and spread.

6. Aphids

Aphids are a pest that can attack the soft leaves and stems of a begonia. These tiny green bugs can fly in, land on the sappy stems of the begonia and suck the sap. They will release a sticky substance called honeydew which can cause sooty mold growth and attract ants.

Treat aphids by squirting them off with a hose. Large infestations can be treated with Neem oil which will coat the bug and they will eventually die.

7. Powdery mildew

Powdering mildew is a white fungus that can form on the leaves of begonias. The white substance looks like white frost and can cover the leaves stopping them from photosynthesizing and can eventually kill the plant.

This can occur if the weather is warm and humid or if lots of rain or water from sprayers sits on the leaves. Prevention is the best method so water the begonias at the roots rather than on the leaves. Surround them with bark mulch to avoid soil splash.

I have always found this problem to correct itself when the weather warms and dries. Affected leaves can be trimmed off and they will be replaced with new ones.

How to revive a dying begonia

Here are 5 easy ways to revive a dying begonia.

1. Avoid watering on the leaves

The first step is to avoid any problems that can be caused from water landing on the leaves. Avoid overhead watering, sprayers and only water at the root level. This will reduce the moisture on the leaves helping to prevent bacterial and fungal infections.

2. The right amount of water

The next step is to get the balance right with the correct amount of water. Too much water can cause root rot and not enough can cause the plant to dry, wild and die.

Allow the begonias to dry out between watering and only give it more water if the soil is dry 1-2 inches below the surface. A moisture detector can be used or use a small spade to dig and see if the soil is dry. Your finger also works well.

3. Plant in part shade

Moving a begonia to a part shade position or a bright window rather than direct sunlight can be a great way to save the plant. Very hot sun can burn the leaves and cause the plant to dry and wilt. Brown leaf tips are a sign that the plant could be getting too much sun.

Move outdoor potted plants into part shade and move indoor begonias away from direct sunlight on the leaves. A hot, sunny window can burn sensitive begonia leaves particularly if they have been grown indoors at the garden center and you have just taken them home.

4. Trim off damaged leaves

The final step to help to revive a dying begonia is to trim off the damaged leaves. These leaves will not recover and will be replaced with new ones once the plant is healthy again.

Trim off dry, black or yellowing leaves once you have addressed the cause of the problem. You will soon see new sprouts to replace old and the begonia will have the best chance of recovery.

Note: Do not remove more than 1/3 of the leaf coverage in one go, do this gradually unless they are infected.

5. Mulch

Mulch is an important step to prevent your begonias suffering from diseases in the future. Mulching with bark or tree mulch will stop bacteria and fungus from splashing up onto the leaves from the soil.

Indoor begonias can be mulched with an indoor bark mulch or coconut fiber which will both look great and keep the soil in place.

Why Are My Begonias Dying? | Summary

Begonias can be saved if you follow the few steps listed above. Weather conditions have a lot to do with the begonias success but indoor begonias are totally reliant on you to live well. A feed of slow release fertilizer like pelleted chicken manure for outdoor plants will give them an extra nutrient boost to recover.

For indoor begonias, use an indoor plant food when the weather warms to keep them healthy and well fed.

Begonias are a forgiving plant so these tips can help to save a dying plant and help it recover quickly.

References

1. Michigan State University, 2011, Bacterial leaf spot of begonia, Accessed 1 September 2021, https://www.canr.msu.edu/news/bacterial_leaf_spot_of_begonia.