Dahlias provide a riot of color and months of flowering in public green spaces

Nectar and pollen

With such a long flowering period, dahlias enhance a location’s scenic value for months. Cities offer the perfect place for them in parks and traffic circles as well as in flower containers. The dahlia assortment is so huge that it includes almost every flower color and many different flower shapes. Single and semi-double dahlias are so rich in nectar and pollen that they attract hordes of bees and butterflies. New assortments frequently become available on the market. Dark-leaved varieties are in high demand and make a beautiful addition to a planting.

Sturdy and not too tall

Dahlia varieties are classified into groups according to the shape of their flowers. The groups used in public green spaces need to be sturdy and not too tall. These locations often don’t provide the kind of support that the taller dahlias need. Among the suitable are:

• Single-flowered Mignon Dahlias. These plants reach a height of up to 20 inches and their flowers are about 4 inches across.
• Topmix Dahlias. These are also single-flowered varieties but their flowers are only a little over 2 inches across. They grow to be less than 20 inches tall.
• Anemone-flowered Dahlias. Their semi-double flowers are from a little over 2 to a little over 5 inches in diameter. Most grow to between 14 and 40 inches tall.
• Cactus-flowered Dahlias. The petals of these double-flowered varieties are rolled inward. Their heights range from 16 to 60 inches, so only the shorter varieties are suitable for public spaces.
• Gallery Dahlias. The varieties in this group produce a profusion of flowers from early summer until well into the autumn and grow from 10 to 18 inches tall.

Grouping together or combining with others

Dahlias make the most impressive displays when grouped together using just one or more varieties. For a more varied effect, dahlias could be combined with other summer-flowering bulbs such as Lilium (lilies), Canna (Canna Lily) and Crocosmia (formerly known as Montbretia). Dahlias can also be planted among perennials such as Pennisetum (Fountain Grass) or Persicaria (Knotweed). No matter what the variety, colorful dahlias will remind everyone that it’s summer – all summer long.

Practical tips

• Since dahlias can be harmed by the slightest frost, be sure to plant them after any danger of freezing temperatures has passed.
• Dahlias are real sun-worshippers, so plant them in a sunny location. A bit of shade is alright, but too much will reduce flowering and produce weaker plants.
• Give them fertile, not too dry soil with good drainage. They will grow in any type of soil. If the soil is not fertile enough, applying an organic fertilizer would be a good solution.
• Plant the tubers so that last year’s remaining stem is just below the soil surface (i.e., not too deep).
• If taller dahlias are planted with sturdy canna lilies, the cannas will help keep the dahlias supported.
• Remove faded flowers to encourage more flowering. Although this might not be feasible for landscaping personnel to do this in public places, the participation of local residents could help.
• After lifting the tubers, plant spring-flowering bulbs in the space left behind.