Begonia 'Black Velvet'

Rhizamatous Begonias prefer a moist but well draining soil, and prefer a slightly a slightly acidic or neutral compost mix. All begonias are frost tender, and Rhizomatous Begonias tend to be grown indoors as houseplants where they prefer growing temperatures of around 21C (70F) and with absolute minimum temperature of 10C (50F). They require good levels of humidity, usually between 40%-70% (dependent on the specific cultivar/variety) and they do well in a bright light position. However, they do not want to be sitting in direct or full sun conditions. An hour or two of sun in the early morning or late evening can may be fine for some varieties, and getting the lighting right is key to ensuring a good colouring of the foliage. If light is coming from one side, ensure you turn the pots frequently to ensure even growth across the plant. Plants can be repotted as they get bigger, ensuring to only increase the pot size gradually by an inch or couple of centimetres at a time, and a good time to do this is in mid spring when the plants are about to start growing again after the cooler winter.

Rhizomatous Begonias can be propagated by using pieces of the rhizome. They act as a type of stem cutting. You can use either a shallow pot or a tray, filled with suitable cuttings or multipurpose compost. Water the pot or tray from the base (do not water from above) by placing it in another tray or container with a shallow layer of water. The water will be drawn up into your cuttings tray. Using a clean knife, cut sections of the rhizome from the parent plant into two inch sections, removing the largest of leaves. Make sure the rhizome has good contact with the compost, but not buried more than half way up the stem. Keep the cuttings moist (no wet) and humidity high by covering the tray or pot with a clear lid or clear bag. Place the tray or pot in a warm environment of around 18-21C (65-70F). After a few weeks, roots will form and new growth will appear from the nodes producing a new plant. Once rooted and signs of new growth are visible, pot on the individual cuttings in fresh compost in individual pots to grow on. As most Rhizomatous Begonias are grown as houseplants, cuttings can be taken any time of year however they may root and grow quicker during the growing season of Spring and Summer.

Rhizomatous Begonias may be propagated by leaf cuttings to make additional plants. As they are generally grown indoors as houseplants, this form of propagation can be done anytime of year, and generally will produce many new plants from one cutting. There are three methods to propagate Rhizomatous Begonias, which involve either sections of a leaf, leaf petioles or a single leaf. All require first the preparation of a shallow pot (or tray) of a well draining compost mix. This should be watered from below using another tray or placing in a sink. Do not water from above. Depending on the variety or size of the foliage, you can then follow either of these methods; 1) Leaf Squares/Sections - This is suitable for large leaved Rhizomatous varieties. Cut off a large leaf. Then using a clean knife, divide the leaf into square sections of approximately three quarters of an inch square in size, or even an inch square. Arrange the leaf cuttings flat on the surface of the compost approximately half an inch apart so that they are making contact with the compost, top side facing upwards. Ensure that they are evenly spaced out and have good air circulation around them. If the variety has hairy or heavy wrinkled foliage, sometimes it is better to place the square sections vertically in the compost rather than flat to avoid them rotting off too quickly - bury just deep enough to hold the section in place, and ensuring the base of the leaf is in the compost and not the top of the leaf; 2) Leaf Slashing - This is suitable for large leaved Rhizomatous varieties. Cut off a large leaf. On a flat surface, turn the leaf over to expose the underside and the leaf veins. Take a clean knife and make 1-2cm slashes across a number of leaf veins, thus damaging it slightly. Try to keep the cuts spaced out over the leaf and no more than one cut per square inch. Turn the leaf back over and place it flat on the compost. Ensure the underside of the leaf (particularly those areas damaged by the cuts) come into contact with the soil. If this is difficult, you can use wire staples or something similar to peg it into the compost (such as the unfolded metal from paper clips). 3) Leaf Petioles - This is suitable for the smaller leaved Rhizomatous varieties. Cut off some of the leaves, including their leaf stalk (or petiole) with a clean knife. Leave approximately two inches of petiole attached to each leaf. Using a dibber, make a small hole in the compost just sufficiently deep to hold the cutting in place, and at a slight angle so that the leaf is almost lying flat on the surface. Firm the compost around it. You can place numerous leaves in rows or arrange them so that they have at least half an inch gap between them. For all the techniques above, once the cuttings are in the tray or pot, cover them initially with a clear propagator lid (or similar) to allow light in, ensure humidity is kept high, and keep it in a warm place around 21C/70F. After a few weeks, little plantlets will start to emerge. Harden these off by first removing the propagator lid for a few days, then pot up the plantlets when they are large enough to handle without damage.