Calceolaria (Slipper Flowers)

Few plants are more striking than the hybrid calceolaria, with its masses of pouch-shaped blooms, mostly spotted, and in just about every color but blue.

It can be grown in all mild climates in bush houses or sheltered verandas, but in districts colder than Sydney it needs a glasshouse. The flowers, 50 to 100 to a bush, begin in August and last well into the warm weather.

Sow seeds in pots or boxes containing a good compost-loam, made up of clayey garden soil (two parts), sand (one part), rotted cow manure (one part), well-decayed leaf-mold (one part), and a little charcoal.

Sow in January – February. Scatter the seed thinly, press lightly with a flat piece of wood, then sprinkle finely sieved leaf mold and fine sand on top, not deeper than ΒΌ inch. Water carefully.

Keep the pots in a glasshouse or glassed-in veranda or frame, and shade in hot weather. Once the seedlings appear, place pots in a saucer of water, letting it seep through. The seedlings are allergic to damping-off if constantly watered overhead.

As the plants increase in size, give them a “saucer” drink every day. When plants develop two small leaves, pot them up singly in “thimbles” (2-inch pots), repotting them later in 3-inch, 4-inch, and finally 6-inch to 9-inch pots. The leaves are inclined to flop on to the pot rims, which when wet may cause rotting, so pot them fairly high.

Calceolarias are annuals, but well advanced plants can be “slipped” and many new plants raised from the cuttings.

Take fairly stout stems with a few well-developed leaves, let the cut stem ends dry for an hour, then embed in sandy loam or vermiculite until they develop roots. In this way plants can be carried over from year to year.

When plants are budding feed with diluted liquid manure.

White flies, a common pest of the glasshouse, cause considerable damage in summer. Spray with D.D.T. emulsion or nicotine sulfate. Calceolarias are also subject to attack by green flies (aphids), which D.D.T. will deal with.

Grey mold (botrytis blight) can be checked by spraying with Zineb and by removing badly affected leaves and keeping the foliage dry.

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