Rex begonias are grown for their leaves, and those leaves can make new plants. The RHS lists Begonia rex hybrids and B. masoniana (iron cross begonia) as suitable for leaf cuttings. Iowa State University Extension names the same two as the houseplants best propagated by leaf-vein cuttings.

This only works because Rex types are rhizomatous begonias. Do not assume a cane begonia will do the same. For polka dot begonia and other cane types, see our Begonia maculata stem cutting guide.

Three ways to use a Rex leaf

MethodHow it worksSource
Leaf-vein (split-vein)Cut the main veins on the underside and pin the whole leaf flatRHS, Iowa State, NC State, Illinois
WedgesCut the leaf into wedges, each with a main veinNC State
SquaresCut the leaf into 2.5 cm (1 in) squares, each with a main vein, and pin them downRHS

The whole-leaf method keeps one large piece that is easy to handle. Wedges and squares spread one leaf across more pieces. In each case, new plants form where a cut vein meets moist compost.

NC State’s Extension Gardener Handbook explains why this works only for some plants. A leaf cutting has no axillary bud, so it must form new adventitious buds. Most plants cannot, and a cut leaf simply roots a little or decays. Rex begonias can.

When to take leaf cuttings

The RHS suggests May or June for Rex and B. masoniana leaf cuttings. Its general leaf-cutting advice is spring to early summer, early in the growing season. Iowa State says most houseplants can be propagated any time of year, with early spring ideal.

What you need

  • A healthy, newly matured leaf. The RHS specifies newly matured leaves. Iowa State says firm and healthy. Avoid damaged leaves or ones with pests.
  • A shallow tray of cuttings compost. The RHS uses sandy, peat-free cuttings compost, or equal parts multipurpose compost and sharp sand or perlite. Iowa State lists perlite, vermiculite and peat mixes.
  • A sharp, clean blade. Illinois Extension sterilizes tools in alcohol before and between cuts.
  • Pins or weights. Hairpins, floral pins, bent paper clips or small stones (Iowa State).
  • A propagator or clear bag.

Method 1: leaf-vein cuttings

Combining the RHS and Iowa State steps:

  1. Cut off the leaf stalk.
  2. Turn the leaf over. With a sharp blade, cut through the major veins on the underside. The RHS spaces cuts about 2.5 cm (1 in) apart.
  3. Brush rooting hormone onto the cuts if you want to. Iowa State lists it as optional.
  4. Lay the leaf top surface up, so the cut veins touch the moist compost.
  5. Pin or weigh it down at intervals. NC State adds that if the leaf curls, you can cover its margins with a little rooting medium.
  6. Water in well and let the tray drain.

Method 2: wedges or squares

NC State describes cutting the leaf into wedges so each piece has a main vein. The RHS gives a similar option: squares 2.5 cm (1 in) across, each with a main vein, pinned to the surface of the compost.

Treat each piece as a small leaf-vein cutting. Keep the vein in firm contact with the compost and pin pieces that lift.

Conditions while they root

FactorWhat the sources say
Temperature18–24 °C (64–75 °F) in a propagator (RHS begonia guide); about 20 °C (68 °F) (RHS leaf cuttings)
HumidityHigh; use a propagator or clear bag (RHS); Iowa State says keep a bag loose to allow air exchange
LightGood light but not direct sun (RHS); bright indirect light, as too little light slows rooting (Iowa State)
MoistureKeep the medium moist; re-moisten if it dries (Iowa State) but never wet (RHS)
AirAir covered cuttings about twice a week (RHS)

Iowa State says plantlets usually appear in six to eight weeks. As they grow, the original leaf often dies back.

Potting up the plantlets

The RHS pots plantlets individually into 7 cm (3 in) pots once they have two or three leaves. Iowa State separates them by carefully pulling or cutting them apart once they have rooted in, then discards what is left of the parent leaf.

After potting, Iowa State keeps young plants watered and in bright, indirect light. They should establish within a few weeks; begin regular feeding after that.

For established Rex begonias, Clemson Extension recommends a bright spot out of direct sun and evenly moist soil allowed to dry only slightly. It suggests 19–23 °C (66–73 °F), with nights not below 13 °C (55 °F). The RHS gives the same 13 °C (55 °F) winter minimum for B. rex and B. masoniana.

Why leaf cuttings fail

  • Too wet. The RHS says leaf cuttings rot when the compost is too wet. Water carefully and remove decaying material promptly to limit grey mould.
  • Too cold. Plantlet development slows at low temperatures (RHS).
  • Too dark. Poor growth can follow low light (RHS). Iowa State adds that cuttings may rot or dry out before rooting in low light.
  • Veins not touching the compost. Plantlets form where cut veins contact the medium (Iowa State). A curled leaf needs pinning.
  • Pests. The RHS lists aphids, whitefly and mealybug.

NC State notes Rex begonias are prone to botrytis (grey mould) and powdery mildew. It recommends good air circulation, removing dead leaves, and avoiding misting and overwatering. The RHS warns that begonia mildew can be a problem in damp, over-humid conditions. For mature plants, see our guides to begonia powdery mildew, begonia root rot and crispy Rex begonia leaves.

Other ways to propagate a Rex begonia

  • Division. The RHS divides rhizomatous begonias in spring, making sure each piece of rhizome has one or more growing points. NC State lists division as a recommended method.
  • Stem cuttings. The RHS notes that cuttings of rhizomatous begonias may need to be longer than 10 cm (4 in) to include a leaf node at the base.

Our houseplant propagation methods guide compares these with other leaf methods, and our begonia types guide covers care by group.

Pets

The ASPCA lists begonia as toxic to dogs, cats and horses. It contains soluble calcium oxalates, and the ASPCA says the underground parts are the most toxic. NC State also tags Rex begonias for contact dermatitis, so consider gloves when cutting.

References