Geraniums Zonal vs. Interspecific

May 28, 2015 admin

Botanical Name: Pelargonium × hortorum
Height: 15-18″
Width: 10″
Exposure: Full Sun, Part Sun
Performance: Annuals
Bloom: February (Assorted Colors)

Zonal? Interspecific? What do these terms mean?

The, zonal geraniums make up the traditional Maverick series. Zonal geraniums are the oldest and most well known, brought to Europe from frost free South Africa in 1632 by John Tradescant, gardener to Charles 1st of England. These colorful annuals grow upright and produce globular flower clusters above its foliage. Leaves may be accented with faint maroon halos. Just like their native habitat zonal geraniums prefer a mild climate, thriving in 70-75°, and melting in daytime temps rising above 95° and night time temps above 85°. Remove old blooms, the oldest flowers are on top of the umbel.

Interspecific geraniums are a merging of two different species, the zonal and the ivy geranium. This cross created a whole new class of premium geraniums including the Calliope and Caliente series. These geraniums are more heat tolerant and do not diminish as quickly in the Texas heat. Tested at the Dallas Arboretum the interspecifics, lasted well into the summer, definitely more so than their zonal cousins. The plant forms a mounding to semi-trailing habit with improved branching, vigor, and large self cleaning flowers.

According to Dallas Arboretum Plant Trials, geraniums are not low water plants due to north Texas’ high day and high night temperatures and low humidity. Well drained and consistently moist soil is necessary. Plants on automated drip survive the longest due to consistent moisture. Also, it was found that containerized plants fared better that plants in the ground.

Geraniums are a spring time favorite in north Texas. Now, with the birth of the interspecific hybrids the growing season can be extended!