Longwood Gardens' Estate Carnations

by Juergen Steininger

Dianthus caryophyllus at Longwood Gardens are grown from cuttings, which are planted mid May each year. The cuttings of the current display were purchased from California Florida Plant. Peak flower occurs from late September to mid October. The plants continue to flower throughout the winter months until the spring when the old plants are removed and the flowerbeds are cleaned and made ready for replanting.

We employ methods developed in the first half of the 1900s to create the Longwood Carnation display. Metal rod structures on top of the wooden flowerbeds support mesh wires. Layers of wire mesh are adjusted up and down the metal rods to provide optimal support for the elongating flower stems. Height adjustments are made frequently throughout the fist half of the crop cycle to catch up with the lengthening shoots.

The two raised wooden flowerbeds located in greenhouse 8A are each divided into three sections. Each section is designated to 150 individual plants of a particular cultivar. The presently displayed cultivars are 'Adagio' (red), 'Brocade' (orange), 'Chanon' (pink), 'Nora' (pink), 'Sorentino' (red/white), and 'Sparkle' (white/red).

These light loving plants are grown initially at a temperature range of 65F to 60F day temperature and a night temperature of 60F to 55F. Slightly elevated temperatures early in the growing cycle foster growth and plant establishment. Temperatures are later lowered, to a range of 60F to 55F day, and a night temperature of 55F to 50F to manage plant development. Bud development is strongly governed by temperature. Higher temperatures hasten flower development and bloom; however, flower quality deteriorates.

Carnations perform well in a range of growing media as long as it exhibits good drainage and is well structured. The Longwood carnation media contains topsoil, bark compost, vermiculite, peat moss and perlite.

The plants are provided with water-soluble 20-10-20 fertilizer in a concentration of 300ppm once a week. The flowerbeds are frequently flushed with clear water to prevent salt build up in the soil. The frequency of fertilizer application and concentration is reduced during the low light winter months.

The carnation display in greenhouse 8A is accessible to the public every day during normal opening hours.

OUTDOOR CARNATION DISPLAY

The Dianthus barbatus F1 hybrid cultivar Cinderella Mix will be displayed this year in the Idea Garden. Cinderella Mix is a combination of white, carmine, salmon rose, pink, scarlet, and carmine with eyed flowers. These approximately 70cm tall plants are suitable for professional cut flower growers as well as a colorful addition to any home cut flower garden. The plants are relatively more frost tolerant as compared to other Dianthus varieties, yet they do not require vernalization.

Outdoor grown plants develop sturdy stems, which generally do well without staking or support netting.

Cinderella was started from seed on November 01, 2003 in the propagation greenhouse 33I. The germination temperature was 65F to 70F. Germination took place within 7 to 10 days. The young plants were kept in the propagation greenhouse on a mist bench. The plug flats after germination were moved to a slightly cooler environment 60F to 65F. The plug trays soon will be transferred to the Longwood Garden nursery for transplanting into pots. A display of about 25 plants will be planted in the Idea Garden in early April 2004. Cinderella requires about 15 weeks to its first flower, and do well in a sunny spot in the garden.

Other outdoor display carnations include 600 D. chinensis 'Raspberry Parfait' and 700 D. chinensis 'Telstar Crimson' to be planted in mid April 2004 for display in the Brick Walk.

Longwood Gardens http://www.longwoodgardens.org


** Photo courtesy of Juergen Steininger

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published January 01, 2004