Toronto Master Gardener Factsheet    

Originating in the tropics, begonias have been sought after by such illustrious and nefarious plant explorers as Captain Bligh of "Mutiny on the Bounty" fame. The Begonia Family is perhaps the largest and most diversified genus of indoor plants with over one thousand species and thousands of hybrids varying from miniature terrarium-sized plants to giants over six feet in height. Knowing that they grow naturally on the jungle floor, in mossy rainforests or on cool, foggy mountain slopes gives us good information about how to grow them indoors.

Did you know?

Begonias were named to honour Michel Begon (1638-1710), a French government official in the West Indies and Canada who was also an amateur botanist and plant collector. Plant explorers like the famous Captain Bligh transported shiploads of begonias from Jamaica to England. Since their discovery, there has been a great deal of hybridization so that it is almost impossible for the novice horticulturist to know more than a relatively few species of begonias.

Getting to know begonias

Begonia species are characterized by ornamental, more or less succulent foliage with alternate, usually lopsided leaves. The flowers are borne in clusters with each flower being either male or female, both of which appear on the same plant. There are many variations in leaf size, shape and colour, growth habit, inflorescence etc. so that they have been generally grouped according to the types of roots - fibrous, rhizomatous and tuberous. Each of these classifications are divided into many sub-groups.

Fibrous rooted begonias

One of the best-known of this group is the Wax begonia, an everblooming semperflorens begonia named for their waxy, shiny leaves. This is the most popular and widely cultivated, both indoors and outdoors, of the fibrous begonias. Due to extensive hybridization there are variations in the size of bloom, blossom and leaf colour, and the size of the plant. 'Angel Wing' begonias are also members of the fibrous begonia group as are Hairy-leaved begonias.

How to grow them

Wax begonias need sun for best growth, lower temperatures than other begonias, and less humidity and water. Angel Wing and Hairy-leaved types are tolerant of the usual indoor temperatures of our homes, but require good light conditions.

Propagation

Wax begonias may be grown from seed or propagated from cuttings. Angel Wing and Hairy-leaved types are best propagated by stem cuttings. Here's how to root stem cuttings:

1. In spring, choose a shoot or stem tip with at least two pairs of healthy leaves and a growing point.
2. Trim off the stem just below a leaf. Remove the lowest pair of leaves.
3. Insert the cutting into prepared seed tray.
4. Water well, cover and keep moist.

When cuttings have rooted, transplant to small pots, pinching back tip growth to ensure a bushy plant.

Rhizomatous begonias

These begonias store moisture and food in horizontal stems called rhizomes located just above or below ground level. They are prized more for their spectacular foliage, usually star-shaped or spiral with nubby, satiny or brocaded surfaces in silver, maroon or green combinations. The better known of these are B. masoniana, the "Iron Cross" begonia, so named because its green nubby leaves have mahogany-coloured markings similar to the German Iron Cross, and B. Rex with heart-shaped metallic leaves the colour of which may vary greatly due to crossings with other species. A miniature Rex begonia is now available, and is popular for growing in terrariums.

How to grow them

Shield rhizomatous begonias from direct sun. They like warmth and humidity, but be careful because too much moisture will cause rotting. During the winter dormant period, fertilizer and water should be applied sparingly.

Propagation

Rhizomatous begonias may be raised from seed or propagated by stem or leaf cuttings. Here's how to root leaf cuttings:

1. Prepare a seed tray with a layer of drainage, a layer of compost and 1ž2" of sharp sand.
2. Choose a healthy leaf, cut it off at the base, lay it upside down on a hard surface, and trim off the edges all around.
3. Cut the trimmed leaf into 2" squares, each square including part of a main vein.
4. Insert each cut section half into the sand. Be sure that the part covered is the part of the leaf which was closest to the stem of the original.
5. Water well, cover until rooted, and keep moist.
New plants will grow from the cut sections. When large enough, remove and pot into small pots.

Tuberous begonias - winter blooming

These bushy, well-branched plants have many large, rounded leaves. The flowers are large and single and they keep blooming from November until April. Due to much hybridization, there is a great variation in colour, including white, pink, salmon, and apricot.

Did you know

Winter blooming tuberous begonias are descended from B. socotrana, discovered on the island of Socrata in the Indian Ocean in 1880. They have been crossed with other species, originally in France and more recently by Scandanavian hybridizers.

How to grow them

Winter-blooming tuberous begonias like cool temperatures and moist, but not wet soil.

Propagation

These tuberous begonias are difficult to propagate or to keep for more than one blooming season. But if the plant is cut back severely and put in a cool place, new shoots may arise which, if cut off and carefully rooted, may produce new plants.

Tuberous begonias - summer blooming

The magnificent and glorious summer blooming tuberous begonias are undoubtedly the crowning glory of the begonia family with their many colours, sizes and forms. Although they may be grown indoors, they are better suited to a shady garden outdoors.

 

Factsheets are produced by the Toronto Master Gardeners in association with the Toronto Botanical Garden. They provide introductory information about a broad range of horticultural topics and are intended for personal use and study purposes. Should your gardening group or organization wish to use multiple copies we ask that you inform the Toronto Botanical Garden at info@torontobotanicalgarden.ca.

Date revised: This factsheet was created prior to May 2005.