Add Gloxinias for Indoor Color

Gloxinias, so gorgeous and in such an array of colors and contours, can be grown in your indoor garden. They also make for great Mother’s day gifts.

They are not as fragile as they appear nor are they more difficult to handle than other flowering plants grown indoors. Florist gloxinias (botanically Sinningia) are the products of years of plant breeding. Their ancestors, the small-flowered sinningias, are not commonly grown but they are a handsome group of pot plants.

All of the species have “slipper-type” flowers, nodding bells with protruding pottchlike throats. From these and other species, hybridizers have evolved our present day gloxinias.

Among the varieties of gloxinias we find the widefaced hybrids in solid colors ranging from pure white through purple and red as well as dotted, margined, splashed and striped ones; other hybrids with huge flowers with frilled and twisted petal tips and the varicolored compact forms.

gloxinia watercolor plate

The slipper forms, crosses between the species and the hybrids, are interesting and beautiful. Some of these have medium-sized flowers with nodding heads; others display large flowers with turned-back petals.

Then there are the gloxineras, hybrids between two genera, sinningia and a related plant, rechsteineria. The gloxineras have the small slipper type flowers but instead of producing one to a stalk as in gloxinias, they produce from two to eight. Gloxineras come in shades of pure white, shell pink, coral, lavender, deep rose and red and combinations such as white and pink and lavender and rose. Culture is the same as for gloxinias.

There are some double forms of gloxinias but they are not widely distributed. Variegated forms in gloxinias are rare but I do have one which I think promising. This one, a sport of a red-flowered seedling, has leaves of green and pink, green and white, pink and cream, and solid cream.

If gloxinia tubers are out of season locally just order them from a specialists. These folks, stationed from coast to coast, ship tubers or plants during most of the year.

Planting and Culture

Plant gloxinia tubers in sterilized porous soil such as you use for African violets care or other house plants. Some growers plant them in a “synthetic” soil mix or sphagnum moss, peat moss, perlite, vermiculite, charcoal and processed cow manure. If you want to try this “synthetic” mixture you’ll have to fertilize the growing plants every week.

Fill the 5 to 6″ inch pot to within two inches of the top with soil. Center the tuber and cover it with soil. Set the pot in warm water and when water creeps to the top of the soil remove the pot and place it in a well lighted spot such as an east or south window, or under fluorescent lights.

Household temperatures of 70 to 75 degrees during the day with the usual drop of ten degrees at night are conducive to good gloxinia growth.

Keep the soil lightly moistened until growth shows, then water thoroughly whenever the topsoil feels dry. After soil-grown plants have been in active growth for about six weeks start them on a twice-a-month feeding program. If you prefer going the “green” route by using organic fertilizer try one of the fish emulsions or fertilize them with manure tea (however the smell indoors may be a little much). Otherwise, any balanced soluble commercial fertilizer will be all right to use. Make sure the soil is moistened before applying any fertilizer – otherwise feeder roots may burn.

If you spill water on leaves of gloxinias growing in natural light blot it so the sun won’t burn the leaves. In the greenhouse where humidity is high, tepid water isn’t likely to mar the leaves. Water spilled on hairy-leaved plants growing under fluorescent lights does no harm. Fluorescents are’ “cool” and will not burn.

Try to maintain 40 degrees of humidity around all of your flowering plants. Put moisture into the surrounding air by setting pots on saucers of moist sand or by housing the whole collection in a tray of moistened pea rock or pebbles.

Your gloxinias will bloom in two to four months from planting time. Depending somewhat on the age of the tuber and the care it has received, it will produce from eight to 100 or more flowers.

After-Flowering Care

After the gloxinia has finished flowering, dry it off by decreasing its water supply. Or cut it back to two leaves, keep it lightly watered, and it will favor you with more flowers.

Store tubers in their pots or by removing them from the soil and placing them in a bag of vermiculite. Storage quarters in temperatures of 50 to 60 degrees keep tubers firm and retard leaf growth.

When they show new growth or when they have been stored two to three months, pot them and bring them into the indoor garden.

Pests and Problems

The most common problem is “legginess.” This is usually caused by insufficient light, but it may be furthered by too much nitrogen in the soil. If you are growing gloxinias in natural light get them as close to the windows as possible without burning their leaves. When growing them under artificial light place them so there is about eight inches between the light tubes and pot rim.

Bud blast is another vexing problem. This may be caused from over-or under-watering, poor ventilation, too little humidity, or thrips. Check your culture and you’ll find out what causes the bud blast on your gloxinia.

Thrips are the worst gloxinia pest. These threadlike insects nip buds and scrape away petal and leaf tissue, leaving scars as their trademarks. As a thrips preventative I like to soak tubers in a solution of Neem Oil as a fungicide and insecticide. After planting the tuber I moisten the top soil with more of the solution and repeat this at six-week intervals.

Cyclamen mite causes twisted center leaves and stunted flowers again I go organic with Neem Oil.

Gloxinia Propagation

Propagate gloxinias through leaf cuttings, leaves slit and pegged to the soil, crown cuttings; tuber division, or seeds.

Choose a leaf near the center of the plant. Cut it with about an inch or two of petiole (leafstalk). Place it in water, damp sand, sphagnum moss or vermiculite. Set it in a light spot. You can hasten growth by placing over them a plastic soda bottle or ventilated transparent plastic bag. If you root them in water you’ll notice the end of the petiole flaring and sending out roots. When the roots are about one inch long plant the cutting in a soil mixture, moisten the soil, and place a plastic soda bottle or drinking glass over it. When new tubers have formed the old leaf may die down. Don’t get discouraged and throw the planting away. If you are curious, poke your finger into the soil and you can feel the small tuber. Keep the planting lightly moistened and in a few weeks new growth will push through the soil. As the plant grows shift it to larger pots. It will flower in a four-or five-inch pot in about six to nine months after planting the leaf.

If your gloxinia has more than one crown you may cut off the extra crowns and root them any way you prefer. Likewise, you can split a tuber, leaving on the severed portion an “eye” or small crown. Plant it as you would a mature tuber.

The most fun of all is growing gloxinias from seeds. You can pollinate gloxinias and raise your own seeds, but better for your first venture would be to purchase seeds from an established grower. One pack will give a wide variety of gloxinias.

Plant gloxinia seeds in milled sphagnum or vermiculite. A good container is a transparent covered plastic soda bottle or plastic sweater box. Remember to add some ventilation. Place the planting medium in the dish, moisten it with warm water and sprinkle the fine seeds on it. Do not press the seeds into the medium and do not cover them. Place the cover on the planting, set it in a warm (70 to 75 degree) spot and await germination.

Check the cover for fogging. If it is holding beads of moisture remove it and wipe it dry. Leave the cover off an hour or so before replacing it. This allays damping-off. Seeds usually germinate in ten days but it may take as long as a month for them to pop through. If you garden under fluorescent lights, place the planting two to four inches from the light tubes. Keep it at this distance even after you’ve spotted the first of your crop.

When seedlings get four good leaves, prick them out and plant in small pots or a community pot of soil. Give them plenty of light four inches from fluorescents or as close to the windows as possible without burning tender new leaves.

Under normal household conditions gloxinias flower in six to nine months from seed. Under optimum conditions such as one might give them with fluorescent lights or a greenhouse, they will flower in four to five months.

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