Begonia is the genus containing more than 2,000 species in the begonia family, Begoniaceae. Begonias are often found growing wild in warm, moist, tropical and subtropical areas. Several species are grown as annuals outdoors for a pop of color in shady locations. Many species grow in the understory of rainforests. The leaves of these plants are large, often marked with diverse colors and patterns. The base of the leaves are oblique, one side attaching to the petiole closer to the stem than the other. There are three main types of begonias, depending on their root structure. These types are fibrous, tuberous and rhizomatous. Fibrous begonias are the ones you often see planted outdoors or sold in the annual section of the garden center. Tuberous begonias have large flowers reminiscent of roses. Rhizomatous begonias often have larger, showier leaves with insignificant flowers. Luckily for us, most of the species in cultivation have similar care requirements, due to their similar natural habitats and environments. These tropical wonders will give an impressive pop of color to any room in your home!
Begonias are one houseplant that can tolerate lower light than most. If planting them as annuals outside, be sure there is plentiful shade. Some species with bronze leaves can tolerate full sun, though it is not true for all bronze leaf varieties. If a begonia is planted in conditions with too much sun, they will get sunburn. Sunburn looks like big swaths of brown on the leaves. The brown portions will not heal and will remain on the plant for the life of the leaf. Indoors, they appreciate bright indirect light, if you can provide it, but tolerate low light conditions, though some species will become leggy if kept in similar lighting as the low end of the spectrum for snake plants or prayer plants. If the space between the leaves becomes long, and the leaves all face one direction towards the light, this is called etiolation and the plant is in need of more light. This can be achieved with a simple relocation, or with the addition of a grow light. Grow lights carry the same risk as the sun. Each grow light is different, so be sure to follow the directions on the packaging. Most grow lights suggest a distance of 12-18 inches above the plant, though some that may even be too close. Always check the manufacturer's suggestions before mounting your grow light.
Begonias are similar to ferns when it comes to watering in both indoor and outdoor conditions. If outside in the ground, they prefer average to slightly moist conditions, though they are prone to root rot if in an overly wet location or area with poor drainage. Indoors or in pots, allow the soil to dry slightly before watering again. Always check the soil before watering. When in a pot, allow the soil to dry approximately an inch down or 25% of the soil mass. When watering, be sure to saturate the entirety of the soil, especially in a pot. When watering from the top of a pot, this looks like watering until excess drains from the bottom. If watering from the bottom, this means placing a pot in a dish or bowl of water until the surface of the soil is damp. This could take minutes or hours, depending on the size of the pot and may require you to add more water to the dish halfway through the watering process. If watering in the ground, continue to add water until you can kick away the mulch and the soil beneath is visibly wet.
Most begonias grow in areas with soils naturally rich in organic matter, or the "dirt" part of potting soil. Some species grow in areas such as cliff faces, though for most begonias, regular potting soil will work well for potted begonias. If planting in the ground, try to avoid areas with heavy clay or poor drainage, as this can lead to root rot if the area remains too wet for too long. Though, if your soil is too rocky, or drains too quickly, begonias will not have the chance to uptake the water that they need before the soil dries out.
Like many other common houseplants, begonias are not overly prone to pests or diseases, but it does not mean they are immune! The following are a few common problems to keep an eye out for and how to treat them if it comes to that point.
Mealybugs are a white, sap-sucking insect that produces honeydew that can lead to sooty mildew. They often hide on the underside of leaves and in tight crevices of new growth. They are easily treated with pesticides, an alcohol mixture, or beneficial insects. For more information on how to identify and treat mealybugs, check out the blog post titled Mealybugs and How to Deal with Them.
White, Dusty Substance on Leaves
If it is on the top surface of the leaf, this is powdery mildew, but if a similar looking problem is on the underside, it is downy mildew. Luckily, they're both easy to treat and prevent. Keeping your area well ventilated is a great way to prevent fungal issues from occurring. When you water, take care to avoid wetting the leaves to help prevent fungal infections from occurring. It is easy to treat with a foliar fungicide spray, such as copper fungicide. Always follow the directions on the bottle when applying any form of pesticide.
Brown Circles on Leaves
This is another type of fungal infection. Unlike the previous powdery and downy mildews, this infection does not have the potential to clear up entirely. All of the same preventative measures apply, as well as similar treatment methods, though you may want to consider a fungicide drench or systemic treatment. Monitor the brown circles and be sure they do not spread to new leaves or increase in side. The brown is necrotic and will not heal. If the browning is more of a swath than a circle and seems to follow the areas of the leaf that get the most light, this is sunburn and does not need a pesticide treatment, but to be moved to a shadier area or away from grow lights.
Spider mites are a common pest in plants that like it a little more on the dry side when it comes to humidity. They are a sap-sucking insect that will leave little pinpoint yellow spots on the leaves and extremely fine webs between the leaves. They can be challenging to remove if not caught early. To learn more about early identification, signs, symptoms, and treatments, check out the blog post titled Spider Mites and How to Deal With Them.
Browning Leaf Tips
Just the tips of the leaves turning brown indicates there is not enough humidity for the begonia to thrive. Removing the brown is up to you, as it will not heal nor cause problems in the future by leaving it on. Moving your plant to the bathroom or the kitchen may help to resolve this issue, as those tend to be the rooms with the highest humidity. You could also invest in a humidifier and place it near the begonia. It does not need to run constantly, but a few hours each day will be beneficial.
Overall, begonias can take some getting used to when it comes to caring for them as houseplants, but take to shade gardens outdoors well. They are a wonderful plant for someone who loves to love on their plants! They come in all sorts of shapes and colors, a collection of only begonias would still be an amazing thing to see! As always, if you are worried about any of your plants in any way, please do not be afraid to reach out. Send a brief description of care, as well as several photos of your plant to firstname.lastname@example.org and I will be able to help!