Philadelphus ‘ORSTPHILx2’

Philadelphus ‘ORSTPHILx1’ Swan Lake® on Low water in June 2022 at UC Davis. Photo: SK Reid

Summary

South Coast Research & Extension Center (South Coast REC/SCREC) is located in Irvine California, this site has a sandy loam soil and plants are irrigated with reclaimed water. UC Davis is located in Davis, California, this site has a silty clay loam soil and plants are irrigated with potable water. More information about the field sites is located in the Nuts & Bolts section.

Swan Lake is a new Philadelphus hybrid and is a medium sized deciduous shrub. New growth on Swan Lake had reddish brown stems that contrasted with their bright green ovate leaves. Clusters of fragrant white flowers with four petals emerge in the spring. The clean, fresh scent was unique, smelling a bit citrusy but also resembling the smell of certain mint-flavored chewing gums. At both sites plants were grown from cuttings received in fall 2020, grown in #1-sized containers, and planted in spring 2021. Swan Lake was evaluated at UC Davis and South Coast REC (SCREC) with site specific performance details and recommendations below.

UC Davis Trial – Davis, CA

Swan Lake arrived to us as rooted cuttings in the fall of 2020. They were planted into #1-sized pots and grown in the greenhouse over the winter before being planted in the field in the spring of 2021 (Photos 13a and 13b). Flowering was observed in May. We watched the foliage quality decline over the summer and by October, Swan Lake was ready to drop its leaves and rest for the winter. We had intended to evaluate this cultivar concurrently in the partial shade field but due to mortality occurring while growing the plants to size we only had enough plants for the full sun field. After assessing the data, we think these plants would have benefited from another year in the pot or in the ground to grow into their true form which is marketed as 6’ tall and wide - dimensions we didn’t come close to reaching at the end of their second year in the ground. Due to the marked decline in foliage quality on all treatments from 4+ to barely 3 at the end of the season, we suggest planting Swan Lake in an area with dappled or afternoon shade in our Region 2, and we would recommend irrigating on WUCOLS Low Category of Water Needs.

South Coast REC Trial – Irvine, CA

               Swan Lake was evaluated in full sun and in 50% shade in Irvine. Foliage quality was best in the spring and early summer when the plants had emerged from dormancy and were pushing out new growth. In the shade, foliage quality was low in April for all treatments as the plants were still leafing out and some of the tattered old foliage remained. Swan Lake flowered reliably from April to June, with a subset of the plants continuing to flower until August. Foliage quality was best in the spring and early summer when the plants had emerged from dormancy and were pushing out new growth. The plants never fully filled out in either the shade or the sun. Overall Appearance values were higher in the shade compared to the sun and plants were also larger in the shade compared to the sun. However, at both the June and September Open Houses the mean Overall Appearance values for both sun and shade plants by participants averaged less than 3. Considering that a 3 is the minimum threshold for acceptable Overall Appearance, the Open House results suggest participants had serious reservations about the performance of Swan Lake. Similar to the results at UC Davis, this cultivar may have benefited from a longer trial period and larger, more mature plants being installed. In the Full Sun trial some mortality was observed on the lowest treatment, though no treatment mortality was observed in the 50% shade field.  As a result, in Region 3 we recommend Swan Lake be classed as Moderate when grown in full sun and Low when planted in partial shade.

Basic Info

Growth and Quality Data

Click Here for Complete Data Set - UCD

Click Here for Complete Data Set - SCREC Sun

Click Here for Complete Data Set - SCREC Shade