Begonia masoniana

Begonia Masoniana Care Guide- Learn How Not to Cross Your Iron Cross Begonia

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Begonia masoniana is classified in the section Coelocentrum, rhizomatous group. It was named for a British plant enthusiast Maurice Mason who obtained it in 1952.

Care guide highlights: Today, this species is one of the most popular among begonias. It requires a very well-drained potting mix and a position away from direct sunlight. Provide regular moisture and bright, slightly filtered light, and good air movement. It looks best if grown in a greenhouse or a large enclosed terrarium, but it could perform quite well if positioned beside an east-facing windowsill with a little extra humidity. Propagate it from leaf cuttings and seeds.

Read on to learn how you can successfully cultivate Begonia masoniana and enjoy the sight of the awe-inspiring foliage patterns and texture, as well as greenish-white flowers.

Introducing Begonia masoniana

Begonia masoniana is differently called B. “Iron Cross“ or Iron cross begonia because of the pattern on its leaves, the distinctive brown or black cross-like leaf markings.

It is an evergreen, creeping, rhizomatous perennial species of the Begoniaceae genus that can grow up to 60 cm in height and spread to 45 cm. It performs best in USD zones 11 and 12.

The members of section Coelocentrum typically occur on limestone rocks in China and Vietnam and the section itself has around 12 members.

One of them is this interesting species once thought to be of hybrid origin. It bears ovate and rough green leaves that are 15 cm long, with a cross-shaped, black, or dark brown center. They can also be yellowish-green with bands of dark brown along the main veins.

Leaves, stems, and flowers are hairy. The flowers are pinkish at first, but they assume the color of apple-green leaves and become greenish-white themselves.

Begonia masoniana flowers

They are slightly fragrant and bisexual, which means that male and female flowers differ. For instance, female flowers have three tepals and the outer pair is greenish-white infused with red on the outer surface.

Some of the cultivars include Begonia masoniana “Tricolor“, B. masoniana var. maculata, B. dregei x B.masoniana, B. versicolor x B.masoniana and others.

Begonia masoniana looks most dazzling if displayed in a greenhouse or a large enclosed terrarium. Nevertheless, you can still keep it as a houseplant, provided that you increase humidity levels.

More on rhizomatous group

Rhizomatous types are fairly tolerant of seasonal dry spells and chills, but their leaves may die or become brown. They are primarily spring-blooming plants and relatively compact.

They should be planted in shallow containers and propagated by division, or by using stem or leaf cuttings.

Rhizomatous begonias send up the growth from parts that creep along the soil surface, which are not particularly appealing, so some plant growers prefer to give their plants a makeover by removing some straggly growth and the plant will immediately look more attractive.

Moreover, rhizomatous plants have wildly varied leaf shapes and patterns and their size varies, too. Flowers send up tiny colorful blooms, especially in late winter – pink, salmon, and white.

They are easy to grow, but they won’t endure constantly wet foliage or consistently damp roots.  Do not drench them.

Begonia masoniana belongs to rhizomatous types

There are some perennial rhizomatous plants like B. coccinea, an angel-wing variety with large flowers and pink veined centers called “Merry Christmas“ and “Mirage“, a spreading rhizomatous type with silver scales above and maroon below and small white flowers. Both varieties are suitable for pots and baskets.

Now before we get down to complete care guide, meet these lovely members of the enchanting Begonia family:

What Type Of Light Is The Most Suitable for This Begonia?

Position Begonia masoniana further away from the direct baking sun since this will rapidly scorch the marvelous leaves.

Instead, opt for a nicely lit position beside an east- or west-oriented window where your Begonia will receive bright indirect sunlight. South-facing windows can work in winter only.

If you are cultivating them in a greenhouse, position them in mid-level light. Outdoors, find a position that provides partial shade, for example, place the plant under a tree.

You can supplement your plant’s exposure to light by using grow lights. Keep them on for at least 8 hours during the day and if it is your only source of light even up to 12 hours. Position the lights around 20 cm away from the plant, keeping in mind that the light is the strongest in the center.

Avoid direct sunlight for Iron Cross Begonia

Ideal Temperature for Optimal Growth

Warm temperatures fasten the period of flowering. For that reason, maintain the temperature levels at 21 degrees C in the summer, with lower nighttime temperatures, ideally around 16 degrees C.

In winter, keep temperatures around 13 degrees C or higher. Begonias don’t like chilly conditions, nor will they tolerate frost. So, if they are outside, don’t forget to relocate them to some less cold place.

Adjusting Adequate Humidity Level for Begonia Masoniana

Humidity levels for Begonia masoniana should be around 50%. To increase it, grow the plant in an enclosed terrarium, group the plants close together to generate their own humid environment after watering.

Alternatively, you can also use a humidifier. Misting is not advisable, as it can create powdery mildew or fungus. Don’t put the plant on pebble trays either, because Iron cross begonia does not like to sit in water.

Choosing the Right Type of Soil

Soil type for Begonia masoniana is rich, porous,  humusy, slightly acidic to neutral (5.5 to 6.5), peat-based with the addition of perlite for indoor cultivation and compost for outdoor, ground cultivation.

In case you are cultivating Begonia masoniana outdoors, combine soil, peat moss, leaf mulch, humus, sand, or pine bark. This will make the medium loose and make the pH level ideal.

Some people have tried adding coffee grounds on the soil surface to retain moisture, so if you love to experiment, give this hack a try.

Begonia masoniana needs rich and porous soil

Potting and Repotting- How and When?

As a rule, repot only when the roots have filled the pot they are growing in. When repotting, do not move Begonia masoniana to a more spacious pot than the former one since no plant wants to swim in its pot. Instead, go for a shallow container, ideally clay or terracotta.

You know it is time to repot if the plant outgrows the old container if the roots start emerging from the drainage holes if the soil becomes too compact and drains poorly. Other scenarios are if the plant gets infected, so repotting can sometimes save the plant.

Related: Picking the Right Pot for Indoor Plants – 6 Rules

Growing Begonia masoniana in a Terrarium

You might be wondering why someone would want to grow Begonia masoniana in a terrarium when you can easily do so in a regular pot. Well, there are plenty of reasons why…

Aesthetically pleasing

Who does not love the sight of a miniature plant world inside a glass terrarium? Whatever plants you decide to plant, it makes a breathtaking display and offers numerous possibilities for decoration. Virtually irresistible!

Not only does it look more aesthetically pleasing than grown in a pot, but it saves space, and care pattern is also easier.

Minimal care

You don’t need to change the growing medium for at least a year. Besides, fertilizing is rarely necessary and so is the removal of fallen blooms or leaves. Apart from that, once established, you can water only once a month or less.

Saves space

A terrarium is a creative and space-saving way to cultivate indoor plants and city-dwellers are in constant search of similar solutions.

Plant shelter

A terrarium protects plants from dry air, heaters, and some pests. However, you should still pay attention that your pets or children don’t accidentally break it.

Keep Iron Cross Begonia in terrarium

Terrarium care tips

Should you decide to grow your Begonia masoniana in a larger terrarium, here are some guidelines that will help you:

  • Seal the top of the container with a pane of glass for increased humidity.
  • Position the container under horticultural fluorescent lights (close to the center of the light, for 12 hours per day) or near a window.
  • Use a porous growing medium that consists of sphagnum moss boiled for the sake of sterilization. Cool it, cut it, dry it and mix it with perlite.
  • Don’t water after planting because the growing medium is still moist.
  • As plants that are enclosed need less frequent watering, water occasionally; to determine the ideal moment to add precious liquid, touch the surface, and add water when it becomes dry; it’s advisable to use distilled water or rainwater.
  • Use paper towels if you add more water than necessary and remove the lid to let it dry.
  • Check the pH level of the soil and if it has dropped below 5.8, add ground limestone.

Does It Require Frequent Watering?

As a rhizomatous plant, Begonia masoniana is capable of storing water and nutrients. And one thing it cannot stand is constantly wet foliage and consistently damp roots. So it is advisable to lean on a drier side.

The most important thing you should do is ensure that the potting mix drains well which will work in your favor and can prevent overwatering and hence root rot. Allow the surface of the soil should to dry out at least 2-3cm between waterings. Avoid watering the leaves and to do that you aim the watering can at the soil surface.

In winter, reduce the amount and frequency of watering and let the soil dry out somewhat. Do not overwater during the growing season.

You can increase moisture by adding mulch or peat. As I mentioned, misting is not advisable for this plant.

Is Fertilizing Necessary At All?

To stimulate flower bud development, fertilize in early spring to late autumn. Use either rich organic manure mixed with the soil or a balanced fertilizer.

This species will benefit from a regular application of a water-soluble fertilizer that contains nitrogen, phosphorous, and potassium in a ratio of 20-10-20.

Follow the manufacturer’s guidelines and cut the amount if you are a less experienced gardener. You can use either solid or liquid fertilizers that are absorbed a lot quicker than the former. Discontinue fertilizing in the colder months.

Two Simple Methods to Propagate This Plant

One foolproof way to propagate Begonia masoniana successfully is by taking leaf cuttings. To do that, you should:

  • Remove a young healthy leaf with 3 cm of its petiole or leaf stalk
  • If the leaf is large, trim the leaf blade to a smaller size
  • Optionally, you can add rooting hormone to the cut ends; although it is not necessary, it contains fungicide which can benefit the plant
  • Alternatively, you can soak your cuttings in a 5 percent bleach solution for 6 minutes to prevent rot
  • Prepare the rooting medium  – peat and sharp sand or perlite and vermiculite
  • Slightly moist the rooting medium.
  • Place the cuttings in the rooting medium.
  • Bury the petiole into the soil and do not cover the leaf blades.
  • Enclose it in a transparent container to increase humidity.
  • Place it in a well-lit area away from direct sunlight. You can also grow cuttings under artificial lights.
  • A new plantlet will appear at the cut end of the petiole.
  • Pot it up and grow a mature plant.

This method works for all begonias with a rhizome, but it is not suitable for cane-like and shrub-like varieties. The ideal time to propagate is early spring.

Begonia masoniana propagation

Aside from the above-described option, you can also propagate it from seeds in a draft-free spot.

First, find a shallow pot to mix the sand and the peat. Then sterilize it by baking it in an oven for approximately an hour at a lower temperature.

After that,  wet it using warm water and let the excess drain out. Tap the seeds out of the paper onto the soil mix, without covering them.

Keep the pot in a humid and well-lit spot. Once you see that one true leaf has developed, pot the seedling by placing it into the new soil. When its size reaches around 4cm, it’s time to transplant it again.

For this method, it would be wise to keep some sorts of records. Write down when you planted the seeds, so to follow the progress. This is particularly important if you propagate multiple Begonias using seeds- you won’t mix which one’s which!

Rejuvenating Begonia masoniana

To make it more lively, cut back the old rhizomes, but not to their woody origins. Rather, save some younger sections and remove straggly growth.

Removing the swollen appendages will make the plant more invigorating and give an old plant a new life.

Pests and Other Issues

Prevention is the best medicine. To begin with, purchase a healthy, pest- and disease-free plant and growing material, avoid pouring water overhead, use sterilized tools, remove dead leaves and flowers regulalry.

However, alluring as it is, Begonia masoniana can sometimes attract pests. Some of them are mealybugs and aphids, which can be removed by using rubbing alcohol with a cotton swab or by using insecticides outdoors.

Keep a vigilant eye on your plant, inspect it regularly for pests and other diseases. If you notice some peculiarity, isolate the plant to protect other healthy plants.

Care tips in a nutshell

  • Provide a very well-drained potting mix
  • Allow 2-3 cm of the soil surface to become dry before watering
  • Position the plant away from the burning direct sunlight
  • Propagate from leaf cuttings and seeds
  • Do not choose a large pot when repotting
  • Do not apply overhead watering
  • Avoid misting and do not use pebble trays

Related Questions

Are coffee grounds beneficial for Begonia masoniana care?

Although coffee grounds are known for improving the quality of the soil, in case of Iron Cross Begonia, they should be used as ground cover only in case you keep the plant outdoors.

How long can you grow Begonia masoniana?

Unfortunately, begonia does not belong to long-lasting plants. On average, they can live around 5 years if you take good care of them. That’s why you should propagate them every year.

Is Begonia masoniana toxic to cats and dogs?

Unfortunately, it is. If ingested, it can cause a series of symptoms some of which ate milder while the others are heavier. These include salivation and vomiting but can also lead to dehydration, and kidney failure.


There is not a living person whom rhizomatous begonias cannot seduce. A marvelous indoor or outdoor scenery, their eyelashed leaves speak and wink at every person who lays their eyes on them.

Good companions of Begonia masoniana are ferns and orchids, which they get along well as a group. Whatever rhizomatous plant you opt for, it is the right choice, because the variety is immense, with all sorts of leaf shapes, textures, and sizes.

Growing these unique plants and observing them grow throughout the year is a very enjoyable experience. As a final touch, don’t forget the power of love and attention. Talk to your plant, play some gentle music nearby- it will make both of you feel calmer and happier!

Which Begonia Masoniana propagation method is your favorite one? Share your precious experience with me in the comments section below!

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