My favorite plant this week: Coreopsis 'Redshift'

I'm attracted to plants with yellow flowers.  I've grown Coreopsis grandiflora with its prolific yellow flowers at periodic intervals but I was never really satisfied with it.  It needed regular dead-heading to look good and, in my garden, it was prone to powdery mildew.  I discovered the hybrid Coreopsis 'Redshift' in 2012 and it quickly became one of my favorite plants.  My original 3 plants are currently blooming their hearts out in the backyard border along the hedge that separates our property from the neighbor below us.  Five additional plants, added to the new backyard border we created as an extension of the small bed around our fountain in early spring, are just beginning to bloom.

Coreopsis 'Redshift' bordered by a hedge on one side and a mix of shrubs and perennials on the other side

My only complaint about the plant is that the blooms tend to face the rising sun, which means that the 3 original plants don't show their faces to greatest advantage, a problem I complained about last year.*

The same 3 plants photographed from the path along the hedge, looking back across the garden toward the house

C. 'Redshift' is part of the "Big Bang" series bred by hybridizer Darrell Probst, who crossed 8 species of Coreopsis to create 'Redshift' and the other plants in this series.   The plants are reportedly more winter-hardy than other varieties of Coreopsis and many, like 'Redshift' produce flowers with colors that vary with the temperature.  According to most descriptions, the flowers open in summer with pale yellow petals and a dark red disk surrounding a yellow button center.  Red streaks extend from the center along the petals of some flowers.  When temperatures cool in the fall, the flowers may turn entirely red.   In my own garden, the temperature fluctuations we experience in the fall, often punctuated by our worst heatwaves, seem to make flower color more unpredictable.

Photo taken earlier this week

Photograph taken for Bloom Day in August 2013

Photo taken in mid-September 2013, probably after an earlier shearing

The plants grow about 3 feet (1 meter) tall and 1.5-2 feet (46-61 cm) wide.  They require little in the way of maintenance and have no serious disease or insect problems, although the crown can rot in moist, poorly-drained soil.  With a late summer shearing, the plants will bloom through fall.  They need full sun.  They're heat tolerant and somewhat drought tolerant and they attract butterflies.

Predictions as to the plant's winter hardiness vary, with some sources stating that it can survive in USDA zone 4 but most claiming hardiness to zone 5.  I can make no personal testimonials on the subject as we don't get freezes here.  However, Allan Becker's discussion of the plant contains some interesting feedback from the breeder on both winter hardiness and how to produce sturdier stems and better flowering, which you can find here.    

Coreopsis 'Redshift' is my contribution to Loree's favorite plants post, which you can find at danger garden.  I'm sufficiently enthusiastic about the plant to be on the look out for other plants in the "Big Bang" series, most notably C. 'Cosmic Evolution' and 'Star Cluster.' 

*My references to the location of the rising sun relative to my garden have created confusion on the part of readers of earlier posts so I thought I'd attempt an explanation here.  Although I'm located on the West Coast and my backyard garden overlooks the Port of Los Angeles, the backyard actually faces roughly southeast.  I live on a peninsula which juts into the South Bay.  The ocean visible in some of my pictures is part of the bay, not the open ocean to the west.  If it wasn't always so hazy, you could see Long Beach stretching along the distant side of the bay.