Hardy gloxinias have little in common with the gloxinia (Sinningia speciosa) cultivated as a houseplant – only the beautiful, large flowers are similar. Here you can read how to successfully plant and care for the exotic perennial.
Profile of hardy gloxinia:
Scientific name: Incarvillea delavayi
Plant family: trumpetvine family (Bignoniaceae)
Other names: Chinese trumpet flower, garden gloxinia
Sowing time: spring
Planting time: spring, outdoors from mid-May after frost
Flowering period: June to July
Location: sunny to partially shaded
Soil quality: gritty to loamy, moderately nutritious, humus rich
These information are for temperate climate!
Use in: flower beds, group planting, planters, borders, flower garden, rock garden, potted garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 6
Bee and insect friendly: Yes
Plant characteristics and classification of hardy gloxinia
Plant order, origin and occurrence of hardy gloxinia
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.
Characteristics of hardy gloxinia
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.
Hardy gloxinia – cultivation and care
Locations suitable for the garden gloxinia are sunny to partially shaded. However, as the name suggests, it can not only be cultivated outdoors, but also in large planters or tubs on the balcony and terrace.
Regarding the substrate, the hardy gloxinia is a bit more demanding, but it is not too difficult either. A humus-rich, not too dry and not too wet substrate is favorable for a healthy growth. It should be lime-free. Heavy soils are unfavorable and must be enhanced. Light soils are mixed with compost, so that they do not dry out too quickly and some nutrients are preserved and are not rinsed out immediately.
- Humus, light to fresh
- Neutral to slightly acidic soil
- Not too dry and not too wet
- Mix heavy soils with sand and compost.
If you take the tubers out of the ground over the winter or if you have bought new ones, they must of course be brought back into the ground. They are pre-cultivated in the house. This has to be done in time so that the garden gloxinias start to bloom early in the year.
- The tubers will be planted in soil from March.
- The pot must be big enough.
- The warmer the tubers are, the better the garden gloxinias will grow.
- From mid-May, when frosts are no longer expected, they can be planted outdoors.
- The heart of the plant must be about 5 cm deep in the ground
- It is important not to damage the roots
- Planting distance in the tub is about 15 cm (6 in), in the field about twice as much
- Don’t press the tuber
- Drainage in the pot is important
- In addition, you can spread a layer of hydrograins over it
- Water abundantly after planting
Not much needs to be said about the care of the hardy gloxinia. It is a very frugal plant in the right location and with good soil conditions. In dry times, the garden gloxinia must be watered regularly. However, waterlogging must be avoided. As with other perennials, watering is not carried out over the leaves, but directly on the root balls on the ground.
As outdoor plants, gloxinias are very easy to care for. A humus-rich soil or a compost dose in spring is sufficient to cover the plant’s nutritional requirements. Alternatively, a slow release fertilizer such as horn shavings can provide the necessary nutrients.
You don’t have to cut the plant. However, it is advisable to remove the seed heads that form regularly. In this way, new blossoms are always created, right into autumn. It is also possible to harvest the ripe seed heads This is how you get seeds that you can sow in spring.
If the garden gloxinia has not yet pulled in its leaves before the first frosts, you cut them off, one hand high above the ground, at least if you want to take the tuber out of the ground. But it is also advisable to do if they stay in the ground. This way you can cover them better, what you should do in winter.
Older plants can be dug out and the bulbous roots divided. These divisions should not be carried out during the growing season because they weaken the plant too much. A good time is in late winter (February), for example when the tuber has been excavated for the winter. For this purpose, a large part of the tuber is separated from the mother plant with a sharp, sterile knife using a smooth cut. Since germs and diseases can penetrate through the injury, the cut should always be as small as possible. The cut surface is either dried in an airy place for several hours or dusted with carbon powder before planting. Both variants contain the risk of infections.
If the infructescences are not removed from the plant after flowering, seeds will form after pollination. The ripe seeds can then be harvested and dried in late summer or autumn.
- Time: early spring (February or March)
- Germination temperature: 22-25°F / 72-77 °F
- Substrate: potting compost or cactus soil
- Fill the substrate into the planting bowl or mini greenhouse and moisten slightly
- Scatter seeds
- only press lightly with a kitchen board or similar
- do not cover seeds with soil (light germ)
- cover with glass, foil or greenhouse cover
- set up bright
- air daily
- avoid direct sunlight (east or west window)
- prick into individual pots after germination
- further cultivation takes place at low temperature (22-25°F / 50-59 °F)
- the foil can be removed when the young plants have three to five leaves
- set outdoors from the end of May
By the way: gloxinias grow very slowly. Plants grown from seeds usually take about three years to start flowering.
Diseases and pests
Bare stems and feeding traces indicate an infestation by snails. A well-loosened soil and regular raking counteract the annoying crawlers. Yellow leaves are usually an indication of waterlogging, where the roots start to rot. In this case, you should enhance the soil quality by adding a little sand, humus or compost for drainage.
The plants pull in their leaves in autumn. The tubers persist in the ground. They tolerate temperatures down to -20 ° C / -4 ° F. Nevertheless, many plants do not survive. However, it is usually not the cold that is to blame, but rather the wet, or a combination of both. Therefore, the tubers should be protected from too much moisture with a thick layer of leaves and brushwood. A better option is to overwinter the tubers, similar to dahlias. This is particularly important for heavy soils.
- Remove tubers from the ground in autumn
- Let air dry for a few days
- Place them in a box and cover them with peat to prevent them from drying out
- Overwinter cool and dark, but definitely frost-free
- Put in pots in-house from February and plant outside from mid-May , fter frosts
Use in the garden
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.