Light
In hot climates, browallia should be grown in partial or dappled shade. It prefers afternoon shade. In cooler locations, it can tolerate full sun.
Soil
Browallia needs rich soil high in organic matter with good drainage. Acidic to slightly alkaline soil is best.
Water
Make sure the soil does not dry out and keep it evenly moist but not soggy. Too much water will result in mainly foliage and few flowers.
Temperature and Humidity
Browallia is a tropical heat-loving plant. Only plant it outdoors after all danger of frost has passed and temperatures have warmed. Even a very light frost can damage the foliage.
Fertilizer
If you start with good, rich soil, browallia will only need moderate fertilization. Apply a low-nitrogen fertilizer a couple of times during the growing season. As with too much water, excess fertilizer will result in mostly foliage instead of flowers. Grown in containers, however, browallia needs more frequent fertilization, about once a month depending on the frequency of watering.
Types of Browallia
Another popular browallia species is Jamaican forget-me-not (Browallia americana). It is often referred to as Amethyst flower or Bush violet—the same common names as Browallia speciosa. It is also grown as an annual that blooms prolifically until the first frost. The difference is that Browallia americana plants have a shrubbier growth habit and might require staking; they also tend to attract butterflies and bees.
Pruning
Though pruning is not necessary for this plant when grown outdoors, if you choose to keep it in containers, pruning is essential to maintaining the appropriate size. Simply give it a gentle shear near the end of the summer. Pinch back gangly vines at any time.
Propagating Browallia
Browallia doesn’t grow well from cuttings, so most gardeners find it easier to propagate the plant from seed.
How to Grow Browallia From Seed
Start seeds indoors eight to 10 weeks before the last frost in your area. Because the seeds require light to germinate, just press them lightly into the soil and keep the soil evenly moist and the temperature around 75 degrees Fahrenheit. A grow light can help with germination. The seedlings emerge in seven to 21 days. Before planting them outdoors, the young plants must be hardened off.
Potting and Repotting Browallia
This makes an excellent container plant. It can tolerate a small pot of only 4 inches, assuming it’s the only variety in the pot; if planted along with other shade-loving perennials, make sure the pot is large enough to accommodate the roots of all plants as they grow. Potting in a container ensures more blooms through late in the season, as it can come indoors at the first sign of frost. In most cases, repotting will not be necessary. Many find it is easier to simply remove the plant from the container when it becomes woody and stops offering blooms.
Overwintering
It is possible to overwinter your container plants if you have a large, south-facing window. Bring them indoors before nighttime temperatures fall below 40 degrees Fahrenheit, and cut the plants back to a manageable size. Keep the soil consistently moist but not wet. In hardiness zones 10 and 11, you can also sow browallia in pots in the fall for winter blooming. Start the seeds in small pots and move them to larger containers as they grow.
Common Pests
Browallia does not have serious disease issues. They might be visited by soft-bodied insects such as aphids, thrips, spider mites, leafhoppers, and whiteflies. These can be controlled with insecticidal soap but browallia is especially sensitive to chemicals in warm weather, which can lead to leaf damage. Weigh whether it’s a real infestation that needs to be treated, or whether the insects can be removed simply with water from the hose.
How to Get Browallia to Bloom
Give each plant 6 to 8 inches of space for growth in the garden, as it can spread out about 1 foot. Ensure they are in dappled shade or even full shade conditions, depending upon the climate. Keep in mind that they bloom readily in zones 10 or 11, but to get blooms from them in other zones, it might be necessary to keep them as indoor container plants. This allows use of the warmth of the home as a way to extend the growing season and get the coveted blooms from Browallia.
