Growing and Caring for Blue Potato Bush: A Comprehensive Guide
Overview
Blue potato bush, also known as Lycianthes rantonnetii, is a striking ornamental shrub prized for its vibrant purple-blue flowers and attractive foliage. Native to South America, this fast-growing evergreen is well-suited to USDA hardiness zones 8 through 11.
Characteristics
- Botanical Name: Lycianthes rantonnetii
- Common Name: Blue potato bush, Paraguay nightshade, royal robe
- Plant Type: Shrub
- Mature Size: 6-10 ft. height and width
- Flower Color: Purple-blue
- Bloom Time: March-October (or year-round in warmer areas)
- Growth Rate: Fast
- Toxicity: All parts of the plant are poisonous, including the inedible orange-red berries
Planting and Growing Conditions
Light: Blue potato bush prefers full sun but will tolerate partial shade in warmer areas.
Soil: Loamy soil should be well-drained and not allowed to completely dry out between waterings.
Water: Regular watering is important, particularly during the first growing season. Water more frequently during times of high heat.
Fertilizer: Apply a slow-release fertilizer in the spring just before new growth begins. If planted in a container, fertilize once a month with a liquid 10-10-10 fertilizer. Mulch roots with compost in the spring and again in the fall.
Pruning
Regular pruning is essential to maintain a pleasing shape and encourage continued blooming.
- Primary Pruning: Prune heavily in the winter months after blossoming has ceased.
- Light Pruning: Light pruning after each batch of flowers will result in a more compact shape and greater blossoming.
- Shaping: Blue potato bushes can be pruned into almost any shape, including tree shapes or topiary lollipops.
Propagation
Propagating blue potato bush from cuttings is relatively easy and safer than foraging seeds from the poisonous berries.
- Cuttings: Take cuttings from summer to early fall, and propagate with these steps:
- Cut a stem of about 4 to 6 inches, cutting below a leaf node.
- Remove leaves from the stem, leaving at least two at the top.
- Dip the bottom of the stem in rooting hormone.
- Insert the stem into well-draining soil.
- Cover with a plastic bag or bottle.
- Place the container in a warm area with bright sun.
- Water well.
- Cuttings will root in about a month.
- Seeds: Harvesting seeds from the berries is not recommended due to the plant’s toxicity.
Potting and Repotting
Blue potato bush can be grown in outdoor containers.
- Container Size: Choose a large pot to accommodate the plant’s height and width.
- Drainage: Line the bottom of the pot with gravel.
- Soil: Keep soil moist and well-drained.
- Light: Keep in a sunny spot outdoors.
- Pruning: Prune lower branches and remaining foliage to the desired shape to train the bush into a tree or espalier.
Overwintering
If blue potato bushes are potted, bring them indoors when the threat of frost arrives. Gradual movement from outdoors to indoors is recommended to avoid stress.
Common Pests and Diseases
Blue potato bush is susceptible to pests such as aphids, caterpillars, and thrips. It may also suffer from blight, damping-off, stem rot, powdery mildew, gray mold, and viruses.
Additional Tips
- Use blue potato bush as a backdrop for smaller shrubs and perennials or as a focal point in a garden.
- Mix it with other plants as a border or grow it in containers for a striking display on a patio.
- Plant in well-drained soil to avoid root rot.
- Protect young plants from strong winds.
- Mulch around the base of the plant to retain moisture and suppress weeds.
- Avoid planting where children or pets may be exposed to the poisonous berries.
