Browallia, (amethyst flower, bush violet) is hardy to zone 8A, otherwise use as an annual.
This plant grows to 18 inches tall with dark blue, blue violet and violet lavender flowers.
Flowering in midsummer through to the end and into the early fall or autumn.
If planting in containers, bring them indoors before the first frost and they will continue to grow and flower.
I would cut them back a fair amount as they will get less sun in the Winter.
You can also dig up a plant or two, cut them back, put into a container and you'll have flowers during winter indoors.
Browallia is a delicate delightful annual with blue flowers. Botanically speaking, it belongs to family Solanaceae, better known as the Nightshade family.
To properly understand the conditions that a plant needs to survive you should always locate its origin and try to understand what conditions suit it when it grows in the wild. Barring a few highly altered hybrids, most plants originated in the wild in some region of the world. When subjected to natural conditions they have mechanisms that allow them to grow and propagate naturally.
In the case of Browallia, it is delicate in northern climates because it is a tropical plant, native of Peru, and as such has little tolerance for cold. Generally speaking you need a greenhouse as it will quickly die when exposed to cold.
It can reach about one to one and a half feet in height and has oval shaped leaves that are about two inches long, and beautiful tubular blue flowers, each about half an inch in length, and half an inch wide at the mouth.
Though I've said the flowers are blue, in different varieties the shades can range across to a beautiful violet.
There are varieties and species with more differences, including Browallia grandiflora, a two foot tall 'giant' whose leaves are smooth and green, and with exquisite flowers that are a bright blue in color with calyx tubes of a beautiful contrasting yellow.
This is a tropical plant native to Peru and must be very carefully cultured in a more northern climate. It is recommended to grow mainly as a greenhouse plant and keep them in pots.
They can be taken out of the greenhouse, and the pots left in the open during summer when they will flower. There are around six species available to choose from.
Browallia is not a plant that a beginner can easily grow from seed.
If you intend to grow this as a pot plant, you will generally be quite successful. I would recommend the dwarf varieties of this genus, including 'marine bells' which have very interesting deep blue flowers, 'sky bells', whose flowers are a beautiful light blue, and the more exotic 'silver bells' whose flowers are white.
Browallia is propagated from seed, but this is not recommended for the beginner for the reasons stated above and beginners are better off buying one from a plant nursery.
It is a tropical plant whose requirements both for care and for germination are not easily understood, and even less easily met.
For those who would like to grow Browallia from seed, the seedling should be planted as one to a pot, and the sowing time is under glass in March.
As they germinate they should be cared for carefully, still under glass, right until June, which is the flowering period, and when they can be put outdoors if you like.
They need a great deal of sunlight and well drained soil.
They will flower from June onwards; only ensure that you put them in the greenhouse at the slightest indication of colder weather, or even during a slightly cold spell.
If you protect them in this way, they will continue to flower in the colder months, and you can have beautiful flowers all through the winter!
Plant seeds indoors at 70 degrees and in 14 to 21 days plant outside after the last frost.
When planting either in containers or in the ground use humus rich soil and keep it moist and well drained. This is a great hanging basket plant.