How to Grow and Care for Gloxinias
The plants commonly known as Gloxinias, or perhaps florist Gloxinias, are mostly varieties of one species, Sinningia speciosa, which comes from Brazil.
The name Gloxinia was given in honour of Benjamin Peter Gloxin, a French botanical writer working at the end of the eighteenth century. The genus name honours Wilhelm Sinning, head gardener at the University of Bonn in the mid-nineteenth century. He was associated with the hybridization and selection work which has given us today one of the most glorious summer and autumn flowering house plants.
These modern hybrids have brilliantly colored trumpet-shaped flowers and very beautiful, large, flat, velvety mid-green leaves. The blooms vary in color from rich crimson, deep red, violet and white to various combinations of such colors. Some forms, called the tigrina gloxinias, have flowers heavily spotted or delicately veined in these colors on a white background, and others have frilled edges, touched with white.
Gloxinias can be grown from seed, cuttings or tubers in late winter/early spring, but they are fastidious plants, needing precise care and attention to grow and thrive. The tubers will survive from year to year but they should not be kept longer than 2 or 3 years as old plants tend to lose their vigour.
How to pot and re-pot
If bought in flower, ensure that the plant has plenty of buds still to open. The leaves should not be torn or damaged and should be deep green - pale plants will have been underfed. Check that there is no rot anywhere on the plant, and take great care when transporting, for the fleshy leaves are delicate in structure and can easily break.
Proper care guide
Atmosphere: Gloxinias should be kept away from draughts.
Cleaning: Not necessary - the spraying will be enough (see Humidity below). Never use leaf shine.
Feeding: Add liquid food to the water every week when the flower buds start appearing.
Humidity: When the temperature rises above 75° F (24° C), mist-spray the air above the foliage with tepid water. Do not spray the foliage directly as drops of water will mark the leaves and flowers. To provide constant humidity, it is also a good idea to stand the pots on trays of moist pebbles or damp peat.
How to divide tubers
Light: Gloxinias require a very light position but need to be protected from full sunlight in the summer.
Potting and re-potting: Use a moist peat-based compost with a drainage layer of sharp sand, and pot up the dormant tubers once in late winter/early spring. Put each tuber singly into a 4-6 in (10-15 cm) pot, making sure that the upper surface of each tuber is level with the surface of the mixture. Water them sparingly at first, increasing the amounts gradually as the growth improves.
Young plants grown
from seed or cuttings should be re-potted in pots which are one size
larger as soon as the old pot fills with roots - about 2 or 3 times
during the growing season. After re-potting, leave plants in the shade without water for 2 days to encourage the roots to grow into the new compost.
Propagation: Use 2-3 in (5-7 cm) long stem cuttings taken from old tubers started into growth in spring. Take each cutting in early summer, and put it in a 1-2 in (3-5 cm) pot of moistened potting mixture. Enclose the hole in a plastic bag or propagating case, and stand it in bright filtered light for about 4-6 weeks, when renewed growth should indicate that a tuber and roots have already formed.
Uncover the young plants only slightly at first, and remove it from the protected atmosphere gradually over a 4-week period, keeping the potting mixture moist. Thereafter, treat the rooted cutting as recommended for a mature plant.
Old tubers can also be cut into pieces, each with a growing point (see right).
All Sinningia speciosas can also be grown from seed sown in early spring or leaf cuttings taken when the leaves are mature in summer (see right). Be careful that the young plants do not rot through over-watering and poor ventilation. Seeds and cuttings of whichever type will root at 70° F (21° C).
How to propagate from leaves
Pruning: You can remove the dead flowers and damaged leaves whenever convenient.
Temperature: Actively growing Sinningias will do well in temperatures between 60-75° F (15-24° C), but they need adequate humidity (see above). In winter the dormant tubers should be kept dry and frost-free. They require a high temperature of 70° F (21° C) to start them growing in late winter or early spring.
Water: Give plenty of water, 2-3 times a week in summer, but never let pots stand in water. Water at the edge of the pot to keep it off the leaves and flowers. As dormancy approaches and leaf color fades, gradually reduce amounts of water until stems die down. Leave dormant tubers completely dry.
What goes wrong
Pale green leaves
Add liquid food to the water
Brown rings on leaves
Tomato spotted wilt virus
No cure: destroy plant
Leaves distorted and sticky with green insects
Spray with pyrethrum or a systemic insecticide
Move to a partially shaded place
Stems or buds rot
Too cold and water remaining on the plant after watering
Move to warmer place and take care that water does not stay on leaves and buds after watering or spraying
Marked by water
Avoid spraying flowers
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