The common nasturtium, Tropaeolum majus, is a popular annual, known for its vibrant, trumpet-shaped flowers and rounded, shield-like leaves. Every part of the plant, from the flowers to the foliage, is edible, offering a distinct peppery flavor. Nasturtiums are generally divided into two categories based on their structure: vining types and compact types. This article focuses on the ‘Alaska’ cultivar, one of the most popular varieties grown today.
Defining the Alaska Cultivar
The ‘Alaska’ nasturtium is distinguished by its striking foliage. Its leaves feature an irregular, mottled pattern of creamy white or ivory splashed across the deep green surface. This variegation suggests a snowy or frosted appearance, which gives the cultivar its name. The variegated pattern makes the plant highly ornamental, even when it is not in bloom.
The variegation in ‘Alaska’ is reliably transmitted through the seeds, unlike many other variegated plants. This characteristic has helped establish it as an heirloom variety favored for its consistent visual appeal. The flowers bloom in a warm mix of colors, including shades of yellow, cream, orange, and deep mahogany red. The bright blooms held above the distinctive leaves add to the plant’s overall aesthetic value.
Growth Habit and Structure
The ‘Alaska’ nasturtium is a non-climbing variety with a compact, mounding, or bushy growth habit. Unlike vining cousins that produce long, trailing stems, ‘Alaska’ forms a dense mound of foliage. It will not develop runners that seek to climb trellises or spill over walls.
Its mature size is manageable, typically reaching a height of 12 to 14 inches with a similar spread of 12 to 18 inches. The bushy form is sometimes classified as a dwarf type. This structure is ideal for gardeners with limited space or those who prefer a tidy garden aesthetic. This compact structure ensures the variegated leaves and flowers remain centralized, creating a lush and contained display.
Cultivation Tips for Bushy Varieties
The compact nature of ‘Alaska’ makes it suited for container gardens and window boxes. Closer spacing is recommended for bushy types compared to vining ones. Plants should be spaced about 6 to 12 inches apart to create a dense mass of color. This tight placement quickly forms a continuous border or vibrant edging.
Nasturtiums perform best in full sun and thrive in well-drained soil that is poor in nutrients. Providing rich, fertile soil or excessive fertilizer will cause the plant to prioritize leaf production, resulting in abundant foliage that can hide the flowers. Regular watering is sufficient, but avoid overwatering, as these plants do not tolerate consistently soggy conditions.