Calibrachoa, commonly known as Million Bells, is a prolific flowering plant recognized for its miniature, trumpet-shaped blooms that closely resemble tiny petunias. This trailing plant is a garden favorite, most often seen cascading from hanging baskets and containers. While Calibrachoa is often grown in portable containers, it can be planted directly into garden soil with the right preparation and care.
Planting Calibrachoa Directly in the Landscape
Calibrachoa is a tender perennial native to South America. Outside of consistently warm regions (USDA Hardiness Zones 9 through 11), it must be grown as a seasonal annual. To ensure maximum bloom production, select a planting site that receives at least six hours of direct sunlight each day. In extremely hot climates, providing afternoon shade can help protect the plants from scorching.
The sprawling, mounding growth habit requires adequate space when transplanted into the ground. Space individual plants approximately 6 to 12 inches apart to allow for proper air circulation and prevent overcrowding as they mature. When transplanting, gently loosen any tightly bound roots from the nursery pot, and set the root ball into the prepared hole so the top sits level with the surrounding garden soil.
Specific Soil and Drainage Needs
Successful ground planting relies heavily on mitigating poor drainage, which rapidly leads to root rot. Native garden soil often holds too much moisture, unlike the potting mix used in containers. The ideal medium must be loose, rich, and highly amended to replicate a fast-draining environment.
Heavy clay soils must be significantly altered by incorporating large amounts of organic material, such as well-rotted compost or aged manure. Coarse sand or perlite should also be mixed in to create a sandy loam texture. This amended structure allows excess water to escape quickly, preventing the roots from sitting in soggy conditions.
Calibrachoa prefers a slightly acidic soil environment to thrive, with a target pH range between 5.5 and 6.5. Higher pH levels can inhibit the absorption of micronutrients like iron. If your soil pH is too high, amending it with peat moss or a sulfur-based product can help lower the alkalinity and improve nutrient availability.
Maintaining Ground-Planted Calibrachoa
Once established in the garden bed, Calibrachoa’s maintenance routine differs slightly from its container-bound counterparts. Ground-planted specimens typically require less frequent watering than those in pots. However, the soil should be kept consistently moist rather than allowed to dry out completely. Always check the soil by feeling the top inch, watering only when the surface begins to feel dry to the touch.
Calibrachoa is a heavy feeder due to its continuous blooming habit. Supplementing the native soil is necessary. Incorporate a slow-release granular fertilizer into the planting hole at the time of transplanting. For optimal flower production, complement this with a balanced, water-soluble fertilizer applied every two to four weeks throughout the active growing season.
These plants are self-cleaning, meaning they naturally drop their spent flowers, eliminating the need for deadheading. If the plants begin to look sparse or leggy in the middle of summer, perform a light trimming. Cutting the stems back by about one-third will encourage new branching, resulting in a bushier plant and a fresh flush of blooms.