Rose That’s Jazz

Rosa "That’s Jazz" is a vigorous dark-red double-flowered climbing rose introduced by Poulsen Roser (Denmark) in the late 1990s. This cultivar won several awards for the combination of its large full velvety dark-red flowers, upright vigorous growth habit and glossy dark-green foliage with good health. This climbing rose blooms abundantly from early summer to frost. This combination of vigorous growth, prolific bloom, and hardiness has made "That’s Jazz" a popular choice in gardens and exhibitions in Europe and North America.

DESCRIPTION OF THE VARIETY

FLOWERING

The flowers of the rose variety "That’s Jazz" are produced in generous clusters from June until the first frost in flushes with short breaks. The buds are rather large and have pointed ovoid shape and initially have blackish dark red colour. There are normally 3 lightly appendaged sepals and there are 2 unappendaged sepals with glandular edges.

The flowers of the rose "That’s Jazz" are large, the average diameter of the open flower is about 10 - 15 cm when fully open. When first opened the flower form is high-centered but quickly becomes more open, cupped as the flower fully opens. The flowers are very double, with the average petal count of about 45 petals per flower.

The flower color is a rich velvety deep red. The red color is consistent (single-toned) and striking; no stripes or variegation is observed on the flowers of this rose variety. The petals of this rose variety have good self-cleaning quality, they normally drop off cleanly before drying, leaving plants tidy and clean. Under normal climate conditions the petals last fairly long, on the plant they last for about 7 days, as a cut flower their lastingness had not been tested.

Fragrance:

The fragrance of this rose is generally reported as light to moderate, the flowers have only a mild old-rose fragrance, easily overpowered by more intensely perfumed varieties.

PLANT
"That’s Jazz" is classified as a modern Large flowered climber. The shrub is vigorous and upright, often reaching 250 - 300 cm (8’ 2” - 9’ 8”) or more, in more favourable climates it can reach up to 300 - 500 cm (9’ 8” - 16’ 4”) in height with a spread of about 100 to 200 cm (3’ 2” - 8’ 2”). Its main stems (basal canes) are quite thick, sturdy and not really flexible, very much like the canes of the Tea Hybrids, bearing normal quantities of the large, pyramidal prickles.

The long and strong canes of this rose variety make it a perfect choice for growing attached to large trellises, obelisks or walls where it will create a dense draping of attractive healthy foliage and velvety red flowers. Since the canes of this rose are not very flexible it is best to bend and fix the canes to the support horizontally when they are still young. Cultivation requires full sun, well-drained moderately fertile soil, regular moisture without waterlogging, and support for its vigorous canes. Pruning and training long shoots on a trellis or arbor is done in late winter.

This rose cultivar is strongly growing, Poulsen labels it vigorous and “eruptive” in growth, and notably cold-hardy - it tolerates frosts down to –15 °C . The heat tolerance appears to be adequate, it is suitable for growing in temperate and warm-temperate gardens; as with most red roses, there is no special heat-sensitivity noted, though in such growing conditions adequate watering is advised.

Foliage:

The leaves of the rose variety "That’s Jazz" are medium sized, semi-glossy and dark green in colour, and described as very healthy. The new canes and leaves have strong red-purple colouring before maturing and turning dark green. There is a normal quantity of the foliage on the plants of this rose variety. The number of leaflets on normal mid-stem leaves is typically 5, including the terminal leaflet. The shape of the leaflets is pointed oval, the shape of the leaflet tip is acuminate and the base shape is rounded. The surface texture of the leaflets is leathery, edges are serrated, the type of serration is medium and single. The foliage of this rose has good disease tolerance, the healthy foliage of this rose rarely shows severe blackspot or mildew under normal growing conditions.

Disease resistance:

"That’s Jazz" shows good resistance to the common rose fungal diseases, especially it is resistant to powdery mildew and rust. Numerous sources confirm that the foliage of this rose remains clean and glossy throughout the season. While no cultivar is immune to black spot, "That’s Jazz" seems less susceptible than many hybrid teas. Its ability to open flowers even in rain suggests rain-tolerance and reduced botrytis and blackening. Thus, black spot and rust may occur, but this variety is generally considered reliable. On the other hand, rosette virus is a concern for all modern climbers in some U.S. regions, though no specific incidence in "That’s Jazz" is documented in the literature.

The rose variety "That’s Jazz" is quite cold hardy, it tolerates frosts down to –15 °C. The RHS rates it as H6, meaning hardy throughout the UK (-20 to -15 °C). In USDA terms this equates roughly to zones 6–8. Heat tolerance appears adequate for temperate and warm-temperate gardens.

The name “Naheglut” (German) or “Naheglanz” alludes to the Nahe River in Germany, reflecting the intense red (“glow”) of the blooms, referring to the radiant beauty of its red blooms. Thus both names highlight the flower color and regional origin.

This rose also has an abbreviated synonym ‘Jazz’.

In Austrian market it is sold under trade name ‘Schloss Rosenburg’.

The name ‘Naheglanz’ appears in some catalogs as a varietal name.

Courtyard

"That’s Jazz" made an impact in trials and awards:

 it received a 1992 Certificate of Merit in Belgium (Rumbeke-Beitem);

  in 1999 it was awarded with ARS Award (USA, Climbing category);

 and in 2000 it gained a Recommendation Certificate at Hradec Králové (Czech Republic).

ORIGIN OF THE VARIETY

The rose variety ‘Poulnorm’ / "That’s Jazz" was bred by L. Pernille Olesen and Mogens Nyegaard Olesen (Denmark) in 1986 by crossing the unnamed rose seedling with the Hybrid Tea rose ’COMsor’ / ‘Norita’. It was introduced commercially by Poulsen Roser A/S around 1997.

USDA 5