The Blue Spur Flower (Plectranthus saccatus) is a delightful ornamental plant known for its captivating blue or purple blossoms. This easy-to-grow species offers continuous flowering, making it a popular choice for garden beds and containers due to its low maintenance and adaptability, appealing to many gardeners.
Blue Spur Flower Characteristics
Plectranthus saccatus is a soft, semi-succulent shrub, typically reaching 1.2 meters tall with a woody base. Its branches are often purple-tinged and finely hairy. The bright green, rounded, aromatic leaves can reach up to 6 centimeters, often featuring large teeth and transparent gland dots on the underside.
The plant’s distinctive tubular flowers, larger than many other Plectranthus species, resemble Jacaranda blooms, earning it common names like “stoep jacaranda.” These lilac, white, or purple flowers bloom year-round in warmer climates, peaking from summer to autumn (November to May in its native South Africa). Their continuous display attracts butterflies and hummingbirds.
Cultivation and Care
Light Requirements
Blue Spur Flower prefers full sun to partial shade, needing several hours of direct sunlight daily but protection from intense midday sun to prevent leaf and flower burn. Indoors, an east or west-facing window provides ideal filtered light. It also thrives in dappled shade, making it a versatile choice for shadier garden spots.
Soil Preferences
Plectranthus saccatus thrives in well-draining soil rich in organic matter. Incorporating compost or worm humus enriches the soil, providing nutrients and improving structure for better water retention and drainage. Adding sand or perlite further enhances permeability, ensuring the loose conditions the plant prefers. It generally thrives in neutral pH soil, ranging from mildly acidic to mildly alkaline.
Watering Needs
Keep the Blue Spur Flower’s soil consistently moist. Check the soil surface frequently, watering when it begins to dry, but before it becomes completely dry. While it appreciates moisture, Plectranthus saccatus does not tolerate waterlogged conditions, which can cause root rot. Water directly at the base of the plant, avoiding wetting leaves and flowers to minimize fungal disease risk.
Temperature and Humidity
Plectranthus saccatus thrives in moderate temperatures and is sensitive to extreme heat or frost. Its preference for shady positions offers some protection from cold winds. In regions with cold winters, bringing container-grown plants indoors is recommended to protect them from freezing temperatures. Good air circulation and ventilation also help prevent pests and diseases.
Fertilization
Fertilize Plectranthus saccatus every two months to support its growth and continuous flowering. A balanced NPK fertilizer like 04-14-08, with low nitrogen and high phosphorus, encourages healthy blooming. Organic options such as bone meal and wood ash can also be used, providing calcium and potassium. During the active growing season, typically summer, feeding every fortnight with a balanced liquid fertilizer stimulates vigorous growth.
Pruning
Pruning is important for maintaining the Blue Spur Flower’s shape and vigor. Regular pruning encourages bushier growth and increases blooms. In early spring or after the main flowering period, prune the plant for neatness and compactness. Groundcover varieties benefit from regular trimming to prevent overgrowth, while shrubby types can be shaped into denser forms. Cut stems at a 45-degree angle just above a leaf node to promote new growth.
Planting
Plectranthus saccatus can be grown both indoors and outdoors. Outdoors, it can be placed in flower beds or pots. It is also suitable for mass plantings, especially under trees where grass struggles, forming a dense groundcover that helps prevent erosion and suppress weeds. For container planting, choose a pot with adequate drainage holes. When transplanting, select a pot at least 2 inches larger in diameter and center the plant with fresh soil.
Propagation
Propagating Blue Spur Flower (Plectranthus saccatus) is straightforward using stem cuttings. Select healthy, non-flowering stems with at least two sets of leaves, and snip just below a node. Remove leaves from the bottom inch of the stem.
For water propagation, place the cut end in a glass of fresh water, ensuring no leaves are submerged, and change the water every few days. Roots typically form within weeks. For soil propagation, insert the cutting into a well-draining potting mix, optionally using rooting hormone, and keep the soil consistently moist. Rooting can take several weeks to a couple of months to establish.
Pests and Diseases
Blue Spur Flower is generally resilient but can encounter common garden pests and diseases. Water-soaked spots or yellowing leaves often indicate excessive moisture or waterlogged soil. Prevent this with good drainage and by watering at the plant’s base, keeping foliage dry. Root rot, caused by overly moist soil, hinders nutrient absorption. Proper drainage and moderate watering prevent this.
Common pests include aphids, thrips, and mites, which feed on plant sap and can transmit viruses. Control measures can include applying specific insecticides or using natural solutions. Good ventilation also helps deter pests and diseases.