Polygala myrtfolia "Grandiflora," also called Sweet Pea Shrub, is a small evergreen shrub from South Africa. This compact bush reaches four to six feet in both height and width at maturity, with bright green leaves and purple flowers that bloom in late winter and early spring depending on the climate. The Polygala myrtifolia can withstand temperatures down to -3.89 degrees Celsius and tolerates periods of drought as well as coastal conditions. If you live in a mild climate, this plant is a fast-growing, low maintenance option for a garden.
Germinate a Polygala myrtifolia plant indoors by filling a seed flat with a mix of half peat and half perlite and moistening the medium. Place the seed or seeds on the flat and just barely cover them with the soil. The seeds should have about 1mm of potting medium covering them, which is equivalent to the thickness of a dime.
Place the seed flat in a room that is about 18.3 degrees Celsius in filtered light. Check the seeds each day, keeping the medium slightly moist. The seeds should germinate in 30 to 60 days.
Pick out the strongest seedling and plant it in a pot, keeping it in the filtered light and watering it as the medium dries. When the plant takes root and strengthens it is ready to be planted outdoors.
Locate a sunny or partly sunny area outdoors with well-drained soil to plant the Polygala myrtifolia 'Grandiflora.' Dig a hole the size of the small pot, gently remove the seedling and plant it in the soil, tamping down around to to hold it in place. Water the seedling deeply.
Water the soil dries out. This plant is quite drought-tolerant so once it takes root it will need only a moderate amount of extra water, if any, to thrive in the environment. The plant does need regular watering, however, during long periods of drought.
Prune the plant after it finishes flowering but cutting long branches back a few inches with pruning shears. This will keep it compact, preventing it from getting straggly.
Polygala myrtifolia "Grandiflora" grows well in a container indoors as well. This may be the only option for those who live in cooler climates.