January 15, 2011
By Rodger Tschanz
University of Guelph Trial Garden manager

At the end of 2010, it is time for me to gather together the successful — and not  so successful — stories from the Guelph Trial Garden.  

Many will be looking ahead to the 2011 growing season to determine what to offer clients in the way of new and exciting bedding plants for use in containers, or ground beds.  I hope I provide some inspiration from my 2010 trial experiences.


Breeders continue to release many new small-flowered petunias every year. Small flowers typically have good rain resistance, resulting in them less likely to look like sodden rags after a pounding rain, compared to larger flowered forms.  Here are some of my favourites from 2010.

Picnic Light Pink:
With a semi-trailing habit, this selection is more compact and upright than trailing petunias, such as the Wave series. It has excellent rain tolerance and prolific season-long bloom, and is suitable for both container and ground applications. It needs spacing no greater than 12 inches to achieve good groundcover in the beds.

Charm series:
This series stands out because of exceptionally small flower size, approaching that of calibrachoa. We trialled both Indigo Charm and Sangria Charm with good success. It is suitable for both ground and container applications, with a moderately vigourous trailing growth habit and good rain tolerance.

Shockwave Coconut:
Shockwave is the small-flowered series in the Wave family of seed-propagated petunias. It has excellent ground-covering vigour and looks good in both beds and containers. It stands up well to pounding rain, and spent blooms fall to the ground, thereby not marring the white appearance of the planting.

Picobella Rose Star:
This is another small-flowered plant propagated from seed. It has more of an upright, bushy habit and excellent season-long bloom. Plant at 12 inch spacing, rather than 16 inch, in order to fill in the canopy.

Midsize-flowered petunias

Black Velvet, Phantom, and Pinstripe:
This is the black family of petunias, newly released from Ball Horticulture. Black Velvet is the first released all-black (really dark purple) petunia flower. Under certain growing conditions, the flower doesn’t open fully and may partially revert to a black and pale yellow star pattern of Phantom. Pinstripe is more noticeably dark purple with a fine white strip running the length of the petals. Of the three, Pinstripe seems to have the best rain tolerance, but in general, the group does not stand up well to heavy rain; these plants will show best if protected from challenging weather conditions. All three can be used in both ground beds and containers, but keep in mind that the colour black can get lost in the landscape of soil and shadows. Inter-planting with contrasting colours (yellow, orange) may help bring out the uniqueness of this flower.

Surprise Hot Rod Red: This catchy name tries to describe this unique colour – a bright red with a hint of blue. This plant has moderate vigour and rain tolerance, and fair season-long bloom.


Pelargoniums, or garden geraniums, are another standby of the landscape industry. Breeding efforts have focused on improving bloom quality and increasing the range of colours of this plant group.

The Calliope and Caliente series of geraniums are examples of such inter-specific crosses. Calliope Dark Red was one of the best performers this year with its large inflorescence, continuous blooming and healthy foliage. It did well in both ground beds and containers, under both high and moderate nutritional levels. The Caliente series has a smaller inflorescence, but it is equally prolific in bloom. Caliente Orange had exceptional bloom performance.

Schone Von Rheinberg Coral:
This geranium had bloom performance as memorable as its name. There are three colours in the Schone Von Rheinberg series; all bloomed well, but the coral stood out in 2010.

Horizon Deep Red:
This is a seed-propagated zonal-type geranium with excellent ground bed bloom performance.

Trailing verbena

Close to 30 different trailing verbena cultivars were evaluated in the 2010 trial, with a full range of colours, flower and leaf sizes. This plant demonstrated effective performance in both beds and containers. It typically does better in the spring and fall. Breeders have worked to increase its heat tolerance, and have also tried to increase its powdery mildew resistance. Of the 30 plants in the trial, only two showed signs of powdery mildew in the fall.

Temari series:
We trialled the Temari Cherry Red and Temari Blue cultivars of this large-leaf verbena type; both had excellent summer-long bloom and powdery mildew resistance.

Empress Soft Pink: Bloom performance on this selection was moderate to good.  The unique soft-pink colour of the flower made it stand out in the trial beds.

Lanai Strawberry and Cream and Magelana Plum Frost:
These two new releases showed moderate to good summer bloom, coupled with good resistance to powdery mildew. What really stood out for me were the eye catching bloom colours; a white and red bi-colour for Strawberry and Cream and a mauve fading to a white centre for Plum Frost.

Something different

I will conclude this article by examining some unusual plants that were trialled and caught my attention.

GoldDust is a cultivar of mecardonia available from Proven Winners. It is a mat forming plant with small dark green leaves that contrast nicely with its tiny yellow flowers. I grew this plant in both containers and ground beds with equal success.  It is a relatively slow grower, so in mixed containers, pick companions of equal slow growth. In the ground, this plant would look great trailing over rocks or along a gravel verge.

Sassy Compact Yellow (Argyranthemum) had great season with long bloom performance. Resembling a small-flowered, more compact version of the Argyranthemum Butterfly, it has applications in both containers and beds.

The Spring Celebrities series of hollyhock will bloom readily in the first year, producing multiple flower stalks throughout the growing season, and never exceed three feet. At this height, it can be grown successfully in containers. The Spring Celebrities’ colours (lilac, pink and crimson) in our trial were affected by rust, but the rust was only noticeable under close observation.

With over 500 different plants in the 2010 trials, it is not possible to describe in this article all the new colours, etc., that are available to you for this coming season.  Visit the Guelph Trial Garden website www.plant.uoguelph.ca/trialgarden for complete ratings on all trial plant materials. If you have further questions, feel free to contact me, at rtschanz@uoguelph.ca.

The 2011 trials are currently being planned. The selection of plants will become finalized in the next few months. If you have plant trial requests, or other suggestions for our trialling program, please don’t hesitate to contact me.