By: Jackie Carroll
A few years ago, a gloxinia flowering houseplant (Sinningia speciosa) was considered a perennial;the plants would bloom and then die back. After a period of dormancy, the plant would regrow, delighting its owner with a fresh flush of big, velvety flowers.
Today’s gloxinias are hybrids bred to quickly produce a large number of blossoms. These gloxinias produce an outstanding display for about two months, but once the flowers fade, the plant rarely comes back because it invests all its energy into flowers rather than sturdy roots. Therefore, these plants are best grown as annuals, and since they are discarded after the bloom cycle, gloxinia flower care focuses on keeping the plant looking fresh while it is in bloom.
Gloxinia flower care is not too difficult. Place gloxinias in a bright area, out of direct sunlight. A location near a sunny window just outside the reach of the sun’s rays is ideal.
Growing gloxinia houseplants thrive in average room temperatures of between 60-75 F. (16-24 C.).
Water gloxinias often enough to keep the soil moist. The leaves develop brown spots if they get wet, so apply the water directly to the soil under the leaves. If allowed to dry out, gloxinias go dormant.
Use a high-phosphorus liquid plant food every two weeks on your flowering gloxinia houseplant.
When growing gloxinia houseplants as annuals, they don’t need repotting. If you pot up the plant in a decorative container or need to replace some of the soil because of accidental spillage, use an African violet potting soil.
Gloxinias on display in the garden center are lovely and well worth the price, but frugal growers may want to try their hand at growing them from seeds. The roots are tender and the plant is not easy to transplant to a larger container when it is young, so start the seeds in a 4- to 6- inch (10 to 15 cm.) pot where it can grow to full size.
Fill the pot to about 1 1/2 (3.5 cm.) inches from the top with African violet potting soil. Sift an additional 1/2 (1 cm.) inch of soil through a screen into the top of the pot so that the tender roots won’t have any difficulty pushing through the soil when the seeds germinate.
Moisten the soil and press the seeds gently onto the surface. Seeds need light to germinate, so don’t bury them. Place the pot in a plastic bag and seal the top to keep the soil moist and the air humid. The seeds will germinate in three or four days. At that time, open the top of the bag, and remove it completely after a week. Mist the soil when the surface feels dry.
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Gloxinias (Sinningia speciosa) produce long-lived flowers that bloom during spring and summer. These tender plants grow outdoors in U.S. Department of Agriculture plant hardiness zones 11 and 12, but are treated as indoor potted plants in most climates. Gloxinias require a fall dormant period for the tuberous roots to rest and recover from the previous bloom season. The plants can resume new growth and produce lush flowers again after they wake from their dormant state.
Snip off the wilted flowers with a pair of clean shears as they begin to decline. The foliage begins to wilt soon after flowering stops.
Reduce watering once all the flowers are removed and the plant has no new buds. Allow the soil to almost dry completely before watering to force the gloxinia into dormancy.
Stop watering after the foliage dies back completely. Store the container in a dark location at 60 to 65 degrees Fahrenheit for two to four months.
Mist the soil surface lightly with water once or twice weekly during dormancy so the roots don't shrivel and die. Inspect the container for new shoot development when you mist the soil, and remove the gloxinia from storage as soon as the first winter shoots appear.
Move the plant to a spot with bright, indirect sunlight once it breaks dormancy. Resume regular watering so the soil remains moist.
The exotic-looking hardy gloxinia or Incarvillea (Incarvillea delavayi) belongs to the trumpetvine family (Bignoniaceae) and consists of 16 different species. The plant originated in western China, where it naturally grows at high altitudes. The hobby gardener also knows the plant as garden gloxinia or Chinese trumpet flower. Despite having the same name as the gloxinia (Sinningia speciosa) cultivated as a houseplant, you should not confuse the hardy gloxinia with this one, since the plants belong to two different plant species and each must be kept very differently.
The broad, expansive perennial is between 40 and 60 centimeters (16 and 24 in) high and just as wide. Hardy gloxinias have bulbous storage roots. The tubers resemble thick “fingers” and are reminiscent of tubers of dahlia.
The unpaired pinnate, dark green leaves are up to 45 centimeters (18 in) long and are located on a long flower stalk that can reach an impressive 60 centimeters (24 in) in length. The Incarvillea owes the nickname “flowering fern” to them.
The funnel-shaped flowers have a maximum diameter of 8 centimeters (3.2 in). Depending on the variety, they appear in white or pink and yellow on the inside. Hardy gloxinias bloom between June and July.
Gloxinia (sinningia speciosa), an herbaceous plant valued for its large ornamental flowers and attractive foliage, is capable of blooming any time of year. The plant usually blooms for the first time about four to 10 weeks after planting. Gloxinia produces flowers in shades of white, orange, pink, blue, red and violet, depending on the cultivar. Native to Central and South America, gloxinia requires a warm climate to thrive and grows best indoors throughout most of the United States. A popular gift plant, gloxinia is often discarded after blooming ends, though with special care, it may bloom again the following season.
Keep gloxinia in a location that receives bright, indirect light throughout the day, such as a north- or east-facing window. Maintain a regular temperature of 65 to 75 degrees F during the day and 55 to 65 degrees at night for optimal growth.
Run a humidifier near gloxinia at all times to raise the relative humidity of the air around the plant to necessary levels. Replenish the water in the humidifier as often as necessary to keep it full.
Water gloxinia plant from the bottom once per week to provide the soil with the moisture it needs without wetting the leaves. Fill a saucer with water and place the plant's container on the saucer. Replenish the water in the saucer until the soil is no longer absorbing moisture.
Feed during winter to provide plenty of nutrients for growth and flowering. Use a liquid houseplant fertilizer at half the strength recommended by the manufacturer to prevent over-fertilizing.
Stop watering gloxinia and transfer to a cool, dark location for six to nine weeks immediately after flowering ends to induce a rest period. Re-pot the plant in a slightly larger container with a fresh growing medium when new growth appears and resume regular care procedures.
Use only room temperature water, as hot or cold water may shock your gloxinia plant.
If a humidifier is not available, place the plant's container on top of a tray filled with pebbles and water to raise humidity. Do not mist gloxinia, as the plant cannot tolerate wet foliage.
When you buy a tuber in the spring, it usually already has one or several sprouts at the top. You can pot it up right away or wait a few weeks or even months: just spritz the tuber with water if you find it becoming wrinkled and it will plump up again. It won’t need light until you plant it, so you can keep it in the dark, at cool to room temperatures, while you wait. To decide when to start a flowering cycle, consider it will usually start to bloom within 2 months of being planted. So you can get it to bloom in mid to late spring, summer or even fall depending on when you pot it up.
Plant the tuber into regular houseplant mix, setting the tuber in soil and filling in all around it, but leaving the top (where the sprout is) uncovered or just barely covering it. A 6-inch (15-cm) pot is usually large enough for a young tuber, although there are dwarf varieties better suited to 4-inch (10-cm) pots.
Water moderately, moistening the mix. As the plant “comes to life”, its watering needs will increase. Water it regularly, when the surface of the soil is dry to the touch. Don’t let it dry out during the growth phase or it will wilt and may lose some its leaves or abort its flower buds.
Move the plant to bright light, if possible with some direct sun. Yes, I know that many sources insist there should be no direct sun, but I disagree. A few hours of direct sun daily, as long as it is not overly hot, gives a denser, sturdier plant. It will do well, for example, near an east or west window, but back from a south one if it gets very hot there. Or draw a sheer curtain between it and the sun during the afternoon. It will also grow wonderfully about 6 to 12 inches (15 to 30 cm) under fluorescent or LED lights using a timer set at 14-hour days or longer.
Although you sometimes see the florist’s gloxinia recommended as a shade plant, that would only apply to outdoor growing. Indoors, it really requires bright light to do well.
The florist’s gloxinia is fine with normal indoor temperatures (60–75 ˚F/15–24 ˚C) and average room humidity spring through summer, but may find the air too dry if you push it into bloom during the winter heating season. If so, consider using a humidifier or a humidity tray. Do not spray the leaves in a vain effort to improve the humidity: that has almost no effect other than staining the leaves and flowers.
Fertilize it regularly too, using your choice of fertilizer. A constant feed method, where you add a small amount of soluble fertilizer (about ⅛ of the recommended monthly dose) at each watering, usually gives the best results.
Keep up basic care as above, including watering, making especially sure not to let it dry out. As mentioned, if yours is on a fall or winter bloom cycle, it may need extra humidity to keep the flowers from drying out.
The buds are impressively large and open into large flowers. It can remain in bloom for about two months.
Usually, the plant goes dormant soon after blooming. You can simply stop watering and, when the foliage starts to wilt, cut the foliage off.
Special Tip: You can sometimes encourage the plant to bloom a second time immediately after the first round of blooms. As it reaches the end of its flowering period, before it has gone to seed, cut the stem back to just above the two bottom leaves and it will usually send up side branches and bloom again. After this second bloom, though, it’s best not to tempt fate and try for a third flowering: that can exhaust the plant. Instead, let it go into dormancy.
Store the plant dry, still in its pot. (You can also remove the tuber from its pot and store it bare, but that involves extra effort on your part.) It will need no water until it starts to wake up on its own weeks or months later, nor will it need light. You can place in a dark basement or a closet if you like. It prefers cooler temperatures during dormancy, down to 45˚F (7˚C), but that is not absolutely necessary. It will do fine under regular room temperatures.
Check the tuber monthly while it is dormant, especially if it is bare, and if it seems to be shrinking and wrinkling, spray it lightly with water. Potted tubers are less exposed to drying out and won’t likely need spraying.
After a few weeks or months of dormancy, the tuber will start to sprout all on its own. Photo: Gardening at 58 North
As mentioned above, when the tuber does sprout, you can either move it to the light immediately and start watering … or leave in dormancy for weeks or months.
You can usually grow florist’s gloxinias in the same pot for 2 or 3 years. After that, just as the tuber starts to come out of dormancy, unpot, removing all old soil and roots, and repot into fresh mix. As tubers grow in size over time, you may want to move it a larger pot.
Florist’s gloxinia ‘Kaiser Friedrich’. Photo: J.b. Rapkins/science
While their growth cycle may be a little more complex than that of other houseplants, gloxinia are pretty simple to propagate. You can grow new plants relatively easily and quickly using leaf cuttings, similar to African violet propagation. Gloxinia can also be propagated by dividing tubers or with stem cuttings.
Hardy gloxinias have a particularly decorative effect when they are planted in small groups in herbaceous beds or borders. They also come into their own very well in the rock garden. The Incarvillea also has a reputation for keeping moles away – how reliable is controversial.
The variety ‘Deli Rose’ is often used to plant rock gardens. Unlike others, it shows its noble dark pink flowers between May and August. Incarvillea delavayi ‘Alba’, however, is characterized by a white flower and blooms between June and August.