Flower Trials

Selecting the best flowers for flower beds

By: Nancy Knauss ©2011
Penn State Extension

This winter, as you are looking through the 2011 seed catalogues and thinking about plants that will fill your garden next summer, consider selecting some of last year’s favorites grown in Penn State Cooperative Extension's Demonstration Gardens. For those of you that are unfamiliar with the gardens, the Penn State Master Gardeners of Allegheny County plant and maintain trial gardens in both North and South Parks. 

The primary purpose of the display beds is to show home gardeners plants that perform well in local soils and climate with minimal maintenance.  Because the planting beds have good soil structure and adequate organic matter, we chose not to rototill this year. One of the main reasons is to reduce the number of weeds in the planting beds, as disturbing the soil in spring brings the weed seeds to the surface where conditions are good for germination.


Research also shows that over-cultivation can destroy the structure of the soil as well as damage earthworms and other organisms. After planting, a granular organic fertilizer is broadcast around the plants. No herbicides, insecticides or fungicides are used. The gardens are planted the first week of June and the annuals are removed and composted in mid-October. 

Demonstration Garden sign

Both gardens are exposed to full sun, and are open and unfenced. The gardens are heavily browsed, so we choose varieties least likely to be damaged by deer.   We do spray the pollinator beds at both South and North Park with a deer repellent called Liquid Fence. We also spray the annuals immediately after planting to deter deer and give them a chance to get established. Plants that are damaged by deer are not planted in subsequent years. The deer population forces us to try new plants every year, while keeping the tried and true.

Unlike last summer, the weather this year was dry and warm, so those plants that tolerate drought and hotter temperatures thrived this year. Overall, it was a great year in the demonstration gardens and we were rewarded with many outstanding performers that thrived under the care of the Master Gardeners. Plants that are considered outstanding performers bloomed all summer with minimal deadheading and had no signs of insect, disease problems or deer damage. 


2010’s favorite plants were selected by you—the gardening public that attended Garden in the Parks Field Day in August. Visitors were given a flag and asked to place it by their favorite plant. The following list includes the annuals that received the most votes. Many plants impressed our visitors, but the one plant that garnered a majority of votes at both North and South Park was Benary’s Giant Wine Zinnia.  The plants grew three and one-half feet tall and produced four- to five-inch diameter double burgundy flowers the color of a rich merlot wine.  The plants held up well in the summer heat and were resistant to powdery mildew for the entire season.   

A new compact zinnia variety that ignited the garden with bright orange flowers was Zinnia marylandica Double Zahara® Fire. The one-foot tall plants were disease-free and thrived during the hot, dry weather with virtually no maintenance. Showy two and one-half inch blooms attracted bees and butterflies to the garden from spring to frost. 


As expected, all of the varieties of globe amaranth planted in the gardens did exceptionally well because of their heat and drought tolerance. In North Park, Gomphrena haageana ‘Strawberry Fields’ received the most votes and was chosen the most popular annual. Strawberry Fields Globe Amaranth flowered all summer producing bright red flowers that were excellent for cutting.

Unlike most globe amaranths which have compact habits, Gomphrena sp. ‘Fireworks’ grows about three to four feet tall, producing numerous sturdy stems that are topped with exploding bursts of 1” hot pink flowers that are tipped with bright yellow. Fireworks Globe Amaranth was introduced in 2009 and based on its’ performance in trial gardens across the country, it is destined to become a popular annual.

Pennisetum setaceum rubrum 'Fireworks'
Pennisetum setaceum rubrum

Fireworks continue to explode in the garden with Pennisetum setaceum rubrum ‘Fireworks’, the first variegated purple fountain grass. The arching foliage is screaming pink with a burgundy mid-vein and burgundy foxtail flowers that nod gracefully above the foliage.  Fireworks Purple Fountain Grass is adaptable to many situations and can be used as a specimen in containers or can be planted in the ground in mass. 


The hot, dry weather dictated some of the best performers and Madagascar Periwinkle cannot be beat for its ability to thrive in tough, dry conditions. Lush plants with intense cranberry-red blooms, non-stop flowering, and virtually no maintenance make Catharanthus roseus Pacifica XP Cranberry an outstanding choice for tough, dry areas. 

Rudbeckia was a new addition to the garden this year and we were pleasantly surprised that the deer did not browse the plants. Rudbeckia hirta ‘Tiger Eye Gold’ has a compact habit and produces long-lasting flowers from summer to fall. Golden yellow petals surround the large, dark brown eyes of the semi-double blooms. 


Another heat and drought tolerant plant, Cleome x Senorita Rosalita® grew 4 feet tall and was topped with lavender-pink flowers that did not require deadheading.  Unlike other cleomes which are thorny and sticky and tend to re-seed throughout the garden, Senorita Rosalita has been breed to be sterile and thornless which makes this Spider Flower a much more desirable selection.

Another top vote receiver was Asclepias currassavica, Annual Butterfly Weed. The prolific bright yellow and red blooms flowered non-stop all season, but it was really the abundance of monarch caterpillars on the plants that stole the show.  Ascelpias is a food source for the larvae of the monarch caterpillar. The eye-catching white, black and yellow striped caterpillars are voracious feeders, and although many of the leaves were stripped from the plant, it was very exciting to draw large numbers of monarchs to the gardens. Annual Butterfly Weed is not only attractive but adults and kids love to watch the caterpillars morph into chrysalises!

Annual Butterfly Weed
Butterfly Weed

The Master Gardeners who volunteer in the demonstration gardens are the toughest critics of the flowers because week after week they spend hours maintaining the plants. It is no surprise that those annuals that require little or no maintenance and consistently look good are ranked highest. Although it did not earn the popular vote, one of their favorite plants in the garden was Gaillardia x grandiflora ‘Mesa Yellow’ with its mounded growth habit and abundance of soft yellow blooms. Mesa Gold Blanketflower held up well during the hot dry weather and continued flowering all season. 

Be sure to include some of these outstanding performers on your shopping list and visit the gardens next summer on Field Day, August 20 to vote for your favorite. The North Park Demonstration Garden is located at the intersection of Babcock Boulevard and Wildwood Road, at the Veteran's Monument across from North Park Lake. The South Park Demonstration Garden is located at the intersection of Corrigan Drive and McConkey Road, just down the road from South Park’s Wave Pool.


These gardens could not exist without the support of our partners from Allegheny County's Parks and Public Works departments. Many thanks to the following local garden centers and wholesale growers that generously donate seeds, plants, fertilizer and mulch to the Penn State Cooperative Extension Demonstration Gardens: Bedner’s  Farm and Greenhouse, Cecil Twp.; Best Feeds Garden Centers, Gibsonia; Eichner’s Farm Market & Greenhouse, Wexford; Hahn Nursery and Garden Center, North Hills; LMS Greenhouse & Nursery, Allison Park; Quality Gardens, Valencia; Reilly’s Summer Seat Farm, Ohio Township; Trax Farms, Inc., Finleyville and Pleasant View Gardens a wholesale grower for Proven Winners.


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