Begonia Grandis Plant Care – How To Grow Hardy Begonia

Begonia Grandis

Last Updated on April 18, 2022 by Admin

The begonia grandis is also known as the hardy begonia for good reason. Its because its varieties are capable to tolerating cold winters. For the most part, begonias are not frost hardy, which is why plant owners often keep them indoors or store them inside come wintertime.

If you don’t want to keep doing the latter year in an year out, the begonia grandis is something you should check out.

Originating from southern China, hardy begonia are tuberous plants that grow into a bushy foliage plant with small pale pink flowers which bloom from mid-summer to early fall.

They grow to about 2 to 3 feet and cover a breadth of about the same size.

Begonia Grandis Plant Care

Begonia Grandis Light

The begonia grandis is one of the few begonia varieties that will do well in a fully shaded area. This is something that not many plants in the genus can do given them most either grow colorful flowers or have variegated leaves.

In either case, bright, indirect light allows them to maintain their beauty.

That’s where the begonia grandis is different. And, it can tolerate low light conditions better than the escargot begonia which doesn’t mind a north facing window.

Thus, the best spots for this plant are in partial shade or full shade. To be more specific, the former refers to 2 to 6 hours of sunlight a day. Whereas the latter is less than 2 hours of sun daily.

Whichever you choose, you want to keep it away from direct sunlight as it is sensitive to it.

This makes it easy to keep in indoors as a houseplant. You can put it in your bedroom or bathroom without having to worry about getting tons of light.

Outdoors, it is important to keep it under some kind of shade. This makes it perfect for covered balconies and patios.


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Begonia Grandis Temperature & Humidity

Like light, this is another aspect of the begonia grandis that differentiates it from almost all the other varieties in the genus. It is frost hardy. And, this is why it’s called the hardy begonia.

It is can withstand temperatures down to 23 degrees Fahrenheit. In fact, it can survive the cold winters of the northeast. I know this for a fact because a friend of mind grows one in her place at Brooklyn. And, it has gone through 2 winters without need for too much protection from the cold.

Thus, you can choose from among the different begonia grandis species to grow in your garden if the winters where you live can get very cold.

Basically, if you live within USDA zones 6 to 9, you’ll be able to grow the plant outdoors in your garden or keep it in a container all year round.

Similarly, you can keep it as a houseplant as well. It will be perfectly happy with indoor temperature as long as it doesn’t go too far over 80 to 85 degrees.

Another thing to keep in mind is that the plant is delicate. As such, keep it away from strong winds, people and foot traffic if outdoors.

The plant also likes high humidity. Ideally, you want to keep humidity above 50% when growing it indoors.


Watering Begonia Grandis

begonia grandis

source: wikimedia commons

Like other begonias, the begonia grandis thrives on moist soil. Unlike them, once it matures, it is resilient enough to withstand dry spells. So, it is more forgiving in this department.

That said, it does best when well-watered. But, you always want to be careful about overwatering.

As with other begonias, grandis varieties are susceptible to root rot and fungal infections. So, you always want to be on top of the water situation.

The easiest way to keep track of when your plant needs watering it to check the soil. it the top soil is dry, it is time to water. If it still feels moist, hold off a one to two more days.

By checking the top 1 to 2 inches of soil with your finger each time before you water, you’ll be able to save a lot of headache later on.

In addition to when to water, how you water your begonia grandis is likewise important.

  • Mae sure that you pour directly onto the soil not over the plant. The latter will get the leaves all wet. Because the begonia grandis is prone to powdery mildew and bacterial leaf spot, this is a no-no.
  • Keep pouring until your soak the root ball. This will allow moisture to reach the roots of the plant.
  • Stop once you see water dripping from the holes of the container.
  • Then, allow the excess liquid to drain. This will take anywhere from 5 to over 10 minutes depending on how big the pot is.
  • Once it stops leaking, place the plant back to its original spot.



The begonia grandis needs rich, evenly most soil that’s well-draining to grow at its best. It also does well with acidic or neutral soil.

If you’re planting them in your garden, you’ll want to give them between 1 to 3 feet of space depending on he variety.

Indoors, the plat will do well African violet mix. This is the simplest way to go if you don’t want to make your own potting mix.

On the other hand, you can use regular potting soil and add perlite to improve drainage. Alternatively, you can use peat moss and perlite as well, which gives you enough water retention to keep the plant happy while still being well-draining.

Adding compost in the spring to improve the soil for its growing season also helps. And, come fall and winter, a layer of mulch to protect it from the cold.



Your begonia grandis does not need fertilizer. As such, you can leave it be and add compost to the soil instead. This works well.

Alternatively, you can also apply a balanced houseplant fertilizer (10-10-10) if you prefer. Here, you’ll want to dilute it to 50% strength and feed your plant once a month during its growing season. You don’t need to feed it during the cold months.

Given a choice, compost is the better option. It not only improves the nutrients in you soil but also improves its texture, drainage and aeration. This makes it a better long term options.

Meanwhile, fertilizer leaves salt residue that accumulates over time. As such, you’ll want to flush the soil every so often to get rid of this.


Begonia Grandis Pruning

Most of your pruning will fall under on of 3 categories

  • To extend the blooming time of the plant deadhead flowers that are spent or starting to die down. This will allow your begonia grandis to keep blooming all the way into fall.
  • Size and shape. Like most plants, the begonia grandis will grow much bigger outdoors than inside. But, either way, you’ll want to trim it to keep its size and shape in control be it in your living room or garden.
  • Removing dead and discolored parts. Remove any leaves that are dead, yellow or brown.

The plant can grow up to 3 feet tall and 2 feet wide, it clumping nature can also make it look messy without a little growing.



begonia grandis

source: wikimedia commons

Begonia grandis is often propagated via seed or division. In this section, I’ll go through each one step by step.

It is important t be aware that the plant self-propagates in the winter. As such, you can take advantage of the plant’s self-seeding process to propagate it where you want.

How to Propagate Begonia grandis from Seed

Once things start to cool down in the fall, you’ll see the plant begin to deteriorate. You’ll also see come parts fall off. Don’t be alarmed as this is normal. Leave it be.

It will produce bulbils from its leaves, which are baby tubers. Eventually these bulbils will fall to the ground. And, when spring arrives they will becoming copies of the mother plant. As such, in the garden, you will see more of them pop out.

The good news is, you can collect these bulbilsand plant them where you want. This can be in other sections of your yard or garden, or in containers.

All you need to do to press them into the soil and give them enough light to grow. You don’t want to bury them under the ground.

How to Propagate Begonia grandis via Division

The faster way to propagate your begonia grandis is via division. Keep in mind that this is a tuberous plant. As such, it will look different from many houseplants which have fibrous roots.

Here’s how to divide your begonia grandis.

  • Take the plant out of the pot or dig it out of the ground
  • Carefully brush off any excess soil and check the roots to make sure they’re healthy.
  • Once you remove the excess dirt, you’ll see the tubers which are bulbs.
  • Separate the tubers and plant them into their own containers with well-draining potting soil.


Begonia Grandis Transplanting & Repotting

Only repot your begonia grandis once the roots cover the pot. The plant doesn’t mind being root bound. More importantly, it does not respond to repotting well.

That is, it takes them a while before they’re able to recover from the shock of the move. So, it is a good idea to keep them in their current containers until it is necessary to move them to a larger container.

When you do, make sure to choose one that’s slightly bigger than the current pot. And, one that has holes at the bottom. This ensures enough drainage to avoid waterlogging.



Begonia grandis contains soluble calcium oxalates. As such, it is toxic to both people and animals. The most poisonous parts of the plant are those under the ground. So, at least, unless your cat or dog likes to dig up stuff, then it is less of a problem.

That said, keep young children and pets away as it can cause lip, and throat irritation when ingested. It will also cause swelling and burning sensations.


Pests and Diseases

Pest and Disease can likewise be a problem for begonia grandis.

When it comes to pest, thrips, aphids, mealybugs and mites are the most common violators. They come and try to get the most out of your plant’s stem and leaves. As such, you need to regularly inspect your plant for these problems.

If you do notice them or the damage they do, use a mix of insecticidal soap and water spray to treat your plant.

With diseases, root rot and powdery mildew are 2 things you want to watch out for.

Root rot is caused by waterlogged soil. Allowing your plant to site in water will increase the risk of its root rotting. When this happens, you it can be difficult to revive the plant, especially if the damage is extensive.

As such, avoid overwatering and using well-draining soil are the two most important things to prevent root rot.

Powdery mildew is fungal infection that’s caused by excessive moisture or dryness. Again, water is the culprit here. Because the plant likes moist soil and high humidity, it becomes prone to this.

As such, you want to give it enough sunlight to help dry any excess moisture. Similarly, good air circulation is key.

You also don’t want to water the plant from above which wets the leaves. Misting or watering late in the day are likewise no-no’s.

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