Salvia ‘Mystic Spires Blue’ By Jim Kennedy

This sturdy, well-branched salvia flowers continuously from May until the first hard frost.

Salvia ‘Mystic Spires Blue’ is a blend of innovation and reliability: It has bloomed in trial gardens from May until the first hard frost, displaying bold, blue flowers that cover the plant all season. This new variety has shown its mettle by continuously flowering in heat and humidity from New England through the Deep South. It is a more compact version of the old perennial standby, salvia ‘Indigo Spires’ in Zone 7 or higher.

Unlike its predecessor, ‘Mystic Spires Blue’ reaches a garden height of just 18-24 inches. A great addition to any late-spring or summer program, ‘Mystic Spires Blue’ is ideal for 6-inch or larger pots. Plants in 1-gal. containers will ship at a finished height of 10-12 inches. These sturdy, well-branched plants can be marketed for use in landscapes and containers and added to combination plantings. This variety is available as both unrooted and rooted cuttings.


Choose a well-drained medium with an EC of 0.75-0.80 and a pH of 5.5-5.8. Stick cuttings within 12-24 hours of arrival; cuttings can be stored overnight, if necessary, at 45-50º F. Maintain soil temperatures of 68-74º F until roots are visible. Begin fertilization with 75-100 ppm nitrogen when roots become visible, and increase to 150-200 ppm nitrogen as roots develop.

Once roots are visible, the media should be kept moderately moist and never saturated. As the rooted cuttings develop, appropriate water stress and moderate air temperatures are the most effective growth regulators. When conditions are conducive to stretch, a heavy spray (sprench) 5-7 days after sticking of 0.5-1.0 ppm Bonzi (Syngenta Professional Products) will reduce unwanted stretch.

To promote early branching and improve habit ‘Mystic Spires Blue’ should be pinched 18-24 days after sticking when roots are well developed. Rooted cuttings should be ready for transplant 24-28 days after sticking.

Growing On

Use a well-drained soil with a pH of 5.8-6.3. Night temperatures of 62-68º F and day temperatures of 70-80º F are recommended. ‘Mystic Spires Blue’ should be grown in high light; an ideal range is 6,000-10,000 foot-candles. This salvia has a moderate fertilizer requirement: Maintain constant fertilization at 150-200 ppm nitrogen. Allow the medium to dry slightly between waterings, but avoid periods of sustained wilting.

If plants are pinched in propagation, no further pinch is necessary for 4-inch production. However, plants produced in 6-inch or larger pots may require 1-2 additional pinches. When performing each pinch, four mature leaves should be left on the stem after the terminal is removed. Plants will bloom 4-6 weeks after pinching.

‘Mystic Spires Blue’ is responsive to plant growth regulators. A tank mix (spray) of B-Nine (Chemtura Corp.) and Cycocel (OHP) at 2,500-3,000 ppm and 1,000-1,500 ppm, respectively, can be applied 1-3 times 10-14 days apart as needed. For production in smaller containers such as 4- to 6-inch pots, a Bonzi drench of 1-3 ppm in the liner stage (7-10 days prior to transplant) or one week after transplant will produce a more compact finished plant without affecting bloom size. ‘Mystic Spires Blue’ demonstrates a definite response to Bonzi: Whether using a spray or drench, it is important to keep in mind the desired finished size of the plant. Growers should adjust the volume and rate of application as necessary based on local growing conditions.

No cold treatment is required for ‘Mystic Spires Blue’. Although this variety is not susceptible to any specific insects or diseases in the greenhouse or garden, routine scouting is advised.A 4-inch pot of ‘Mystic Spires Blue’ (one plant per pot with one pinch) will finish in approximately 11-13 weeks from unrooted cuttings and 6-8 weeks from rooted cuttings. Containers that are 6 inches or larger are ideal for summer programs and will finish approximately 12-15 weeks from unrooted cuttings and 7-12 weeks from rooted cuttings.

Jim Kennedy

Jim Kennedy is the technical manager at Ball FloraPlant. He can be reached by E-mail at