News
Annuals Showcase Day at ŠHVU Celje 2025
On Thursday, July 3rd 2025, we held the second Seasonal Plant Day at ŠHVU. The event offered participants the opportunity to view selected varieties, complete trial sheets, and exchange ideas about new collaborations and trial designs that benefit the horticultural profession.
This year’s trial began in the first week of May, featuring varieties of geraniums, surfinias, verbenas, impatiens, and dipladenias. The plants were sourced from several breeding companies—Syngenta, Elsner PAC, Lazzeri, Florensis, Volmary, and Gruppo Padana—and supplied by five nurseries: Picount, Vrtnarstvo Božič, Vrtnarstvo Antolin, Vrtnarstvo Valner, and Vrtnarstvo Hlebec.
All plants were planted either in balcony troughs (50 × 20 × 16 cm, 3 plants of the same variety and supplier per trough) or pots (38 cm, 2 plants of the same variety and supplier per pot). For geraniums, surfinias, and impatiens, we used specialized substrates donated by Njiva d.o.o., while dipladenias and verbenas were planted in a classic peat substrate, also supplied by Njiva d.o.o.
The plants were grown in a greenhouse at ŠHVU until the evaluation in June and maintained under a standard protocol. Irrigation was carried out manually as needed, and once a week the plants were fertilized with a 0.2% Rosasol fertilizer (14-10-25 + 2MgO + trace elements) from Njiva d.o.o. Verbenas were also treated twice with Ortiva.
Once a week, the following parameters were recorded: plant height, number of flowers, and flower stalk length, and average values were calculated for all parameters.
Differences in compactness and flowering
Compact growth and abundant flowering are key traits for seasonal plants, valued by both growers and end customers. Most plants included in the trial developed a dense branching structure, with particularly compact varieties of verbenas, impatiens, and surfinias standing out. Flowering was also abundant in selected varieties, confirming their good performance under local growing conditions.
An interesting result was the difference in compactness of surfinias grown in pots versus balcony troughs. Plants grown in pots generally developed a more compact habit with a prominent central growth, while those in troughs showed a slightly lower center. Sunpatiens varieties of impatiens were exceptionally well-branched throughout and are therefore expected to appear even more frequently in beds and containers.
Future directions
After the plant evaluations, participants discussed ideas for future trials and the challenges faced by seasonal plant producers. A key topic was testing new and lesser-known varieties within individual plant groups to assess their performance under local conditions. Another important challenge is identifying suitable peat-free substrate alternatives. Future trials could focus on how plants establish in coconut- and wood-fiber-based substrates, and how these affect plant compactness and flowering.
Text by prof. dr. Valentina Schmitzer
