Petunias are a favored choice for hanging baskets because they produce a continuous, vibrant display of flowers throughout the season. Achieving a full, lush appearance where the plant material cascades over the container starts with selecting the correct number of plants. This ensures the petunias have enough room to grow vigorously without competing for necessary resources.
Determining the Petunia Count Based on Basket Size
The size of your basket dictates the maximum density of plants that can thrive. For a standard 10-inch diameter basket, plant three to four petunias to ensure a quick and full appearance. This density allows for immediate visual impact while providing room for the plants to expand over the growing season.
A slightly larger 12-inch basket can typically support four to six plants for a luxurious, overflowing effect. When using a 14-inch basket, the ideal count increases to between seven and nine plants, depending on the specific variety chosen.
These guidelines assume you are using petunias established in small cell packs or four-inch pots. The goal is to create density without causing the roots to become overly restricted prematurely. Overcrowding can lead to stunted growth and reduced blooming as the season progresses.
How Plant Variety Affects Density
Not all petunias have the same growth habit, which significantly impacts planting density. Traditional or mounding types grow in a more compact, upright shape and require tighter spacing to achieve fullness. These varieties benefit from the higher end of the recommended planting ranges.
In contrast, modern, vigorous trailing varieties, such as the Wave or Supertunia series, are expansive growers that spread aggressively. These plants require fewer individuals per basket size because a single plant quickly covers a large area. For example, four Supertunias are often sufficient for a 12-inch basket.
Using too many vigorous trailers can be counterproductive, leading to a crowded root ball that struggles to take up water and nutrients. Fewer plants of a highly vigorous variety will ultimately produce a more impressive display than an overpacked basket.
Proper Planting Technique for Hanging Baskets
The foundation of a healthy hanging basket starts with the proper soil medium. Use a lightweight, high-quality potting mix formulated for containers that is moisture-retentive but provides excellent drainage. Fill the basket, leaving an inch or two of space (the lip) below the rim to allow for effective watering.
Before placing the petunias, gently loosen any tightly packed or rootbound roots to encourage outward growth into the new soil. Space the predetermined number of plants evenly, ensuring the top of the root ball (the crown) is level with the surrounding soil surface. Planting too deep can cause stem rot, while planting too shallow risks the roots drying out quickly.
Once the plants are positioned, fill in around them with the potting mix, lightly firming the soil but avoiding excessive compaction. Immediately water the basket thoroughly until water flows freely from the drainage holes. This initial soaking settles the soil around the roots and eliminates air pockets.
Maximizing Growth Through Ongoing Care
Sustaining the high volume of blooms requires consistent maintenance throughout the growing season. Due to the small volume of soil in a hanging basket, water retention is limited, necessitating frequent watering, often daily during hot, dry weather. Keep the soil consistently moist, but not saturated, checking the soil depth with a finger before watering.
Petunias are heavy feeders and quickly deplete the nutrient reserves in the potting mix. To ensure continuous flowering, a consistent fertilization regimen is required, typically involving a high-potency, water-soluble fertilizer applied weekly or bi-weekly. Use a balanced formulation, or one with a slightly higher phosphorus content, to support flower production.
Even with consistent feeding, petunias can become leggy by mid-summer, reducing the floral display. To encourage a fuller, rejuvenated appearance, regularly remove spent blooms (deadheading). Also, pinch back or lightly prune any overly long stems to stimulate new side shoots and a fresh flush of flowers.