Outstanding Garden Plants

Penn State Demonstration Gardens

By Nancy Knauss ©2013
Penn State Extension
Horticulture Educator

Winter snows have arrived and, along with them, gardening catalogues to help us think about the warmer weather and plants we might grow in our gardens this summer.   I thought this would be an ideal time to review some of the 2012 outstanding performers grown at the Penn State demonstration gardens. Last summer was a difficult one for gardeners.  It was a year of extremes—high temperatures, extended periods of drought, and periodic heavy rains were not ideal growing conditions for the annual trial gardens in North and South Parks. The demonstration gardens are planted and maintained by the Penn State Master Gardeners of Allegheny County.

Since the beds were first installed approximately twenty years ago, special care is taken to build up the existing soil with organic matter, as a healthy soil is the key to growing productive, lush plants. For many years, the beds were top-dressed with horse manure in autumn, and leaf compost at planting to improve the tilth and water holding capacity of the soil.  However, this fall we did not apply manure as current research shows that too much manure and compost can increase levels of phosphorus.


Excess Phosphorus

The excess phosphorus is not used by the plants and may run off the soil and enter waterways.  Soil pH may also increase after extended additions of organic matter.  In subsequent years, we will alternate between using cover crops and adding organic matter to help maintain soil fertility.

While the soil at the demonstration gardens is very rich in organic matter which can help to mitigate the lack of moisture, this past summer the beds still required regular watering throughout the extended periods of dryness.

Best Performers

As can be expected, annuals that typically thrive in heat and drought performed exceptionally well.  We grew a number of ornamental peppers and several were voted as favorites at our annual field day in August. 

Capscium annuum 'Calico' sports strongly variegated purple, cream and green tri-color foliage.  The glossy black fruits are added bonus, but are extremely hot and not recommended for eating. 

Capsicum annuum Medusa

Another eye-catching ornamental pepper was Capsicum annuum 'Sangria'.  Its well-branched and spreading habit make it ideal for filling in landscapes and containers. Plants will always have peppers of both purple and red for a colorful display. 

Purple Flash ornamental pepper, Capsicum annuum 'Purple Flash', produces almost black leaves that are splashed with flashes of iridescent purple.  The plants are topped with small, glossy black fruits throughout the growing season.

Deer Resistant Plants

The primary focus of the trial gardens is to showcase deer resistant annuals that perform well in local soils and climate with minimal maintenance.  However, deer browsing in the gardens was unprecedented this year—especially in South Park.  This may have been due to the drought, as many native plants that deer typically forage were not available.  Instead, they ate annuals in the gardens that in previous years were untouched such as globe amaranth, angelonia and lantana.

Salvias continue to be one of the best genera to resist deer browsing.  Salvia farinacea 'Victoria', a mealy-cup sage, is extremely heat and drought tolerant, long blooming and problem free.  It is attractive to butterflies and pollinators, although for best bloom, it requires some deadheading throughout the summer.

Salvia farinacea Evolution Blue

Also long blooming and heat and drought tolerant is Salvia guaranitica 'Black and Blue', the anise-scented salvia.   The cobalt blue flowers are attractive to butterflies, hummingbirds and pollinators.

Another standout that was untouched by the deer was Agastache hybrida 'Arcado Pink', a hyssop with spiky blooms of pinkish-purple flowers on 20-24” tall plants.  With minimal deadheading, the flowers bloomed the entire summer attracting butterflies and bees.

Foliage Plants with Impact

A current trend in gardening is the use of foliage plants to create impact.  Incorporating annuals with varying leaf textures and colors can create spectacular displays.  Some recently introduced fountain grasses are a must-have in the garden. 

For several years we have planted Fireworks fountain grass and once again it did not disappoint.  Pennisetum setaceum rubrum 'Fireworks' performs best in a moist, fertile soil.  Grown for its graceful shape and soft seed heads, it can be used en masse or as a specimen.  Fireworks is the first variegated purple fountain grass.  The burgundy mid-vein is flanked by hot pink margins. 

Purple Fountain Grass and Jade Princess Millet

Pennisetum glaucum 'Jade Princess' was new to the demonstration gardens this year and it was a knockout.  The plants produced dense clumps of wide, lime-green foliage with showy burgundy-red flower spikes.  Plants reach 3 to 4 feet in height and look spectacular used in combination with other warm colors.

Colorful Coleus

Another annual grown primarily for its unique and colorful foliage is coleus.  At one time considered a shade plant, there are now a number of exciting varieties of coleus for full sun.  Gnash Rambler coleus, Solenostemon scutellarioides 'Gnash Rambler' with its gorgeous deep purple ruffled leaves was a garden favorite.

Solenostemon hybrida 'Henna', a new variety of coleus grows in sun or shade and has chartreuse to copper serrated foliage with dark burgundy undersides. 


We used the coleus in the half-moon bed at the end of the walkway in the North Park garden.  The garden was designed with bright colors—oranges, reds and yellows juxtaposed against purple flowers and foliage.  Although coleus is browsed by deer, we choose to use the plants and spray them regularly with deer repellent. 

Mecardonia GoldDust™ packs quite a punch for a diminutive plant.  Tiny, yellow flowers are produced in profusion from May to frost.  The self-cleaning flowers require no deadheading and spread up to 15 inches making the plant an excellent choice for use as a groundcover or spilling over the edge of a container.



Zinnias are hands down the favorite annual grown in the demonstration gardens.  By mid-summer the zinnias are in full bloom and are attracting a myriad of butterflies.  One of the favorites, Zinnia elegans 'Little Lion' offers intense red-orange double flowers reminiscent of a lion’s mane. 

Garden Location

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 that generously donate seeds, plants, fertilizer and mulch to the Penn State Extension Demonstration Gardens:  Bakerstown Feed & Garden Center, Bedner’s Farm and Greenhouse, Best Feeds Garden Centers, Eichner’s Farm Market & Greenhouse, Hahn Nursery and Garden Center, Hess’ Landscape Nursery, Lenix Greenhouse, LMS Greenhouse & Nursery, Michael Bros. Nursery, Quality Gardens, Renee’s Garden, Reilly’s Summer Seat Farm, Soergel’s Garden Center & Orchard, and Trax Farms.


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