Nepeta ‘Blue Ice’ is a new introduction of catmint that offers growers several improvements over the older, more commonly grown Nepeta x faassenii cultivars. ‘Blue Ice’ is extra compact, reaching only 6-10 inches tall and bearing numerous spikes of dainty ice-blue flowers over attractive, aromatic, gray-green foliage. Flowering begins in May and can be renewed or extended until September when the old blooms are removed. ‘Blue Ice’ is hardy in Zones 4-11 and is an easy, versatile perennial that works well as a groundcover and in rock gardens, borders and containers. In the landscape, nepeta performs best in full sun to partial shade where it attracts bees, butterflies and birds when blooming. It generally thrives in sunny locations with dry soils and is considered drought tolerant. Nepeta is not for everyone; it is intolerant of the heat and humidity of the deep South and requires afternoon shade in hot climates.
The cultivars of Nepeta x faassenii are sterile and do not produce seeds; propagation must occur by vegetative means, either from cuttings or by division. ‘Blue Ice’ is vegetatively propagated from tip cuttings by a limited number of licensed propagators. Plant patent protection has been applied for, and self propagation is strictly prohibited. ‘Blue Ice’ is most commonly propagated in the spring and summer months. The cuttings can be taken with or without bloom but, as with most cuttings, will root faster when they are in the vegetative state. Vegetative nepeta cuttings root readily within a couple of weeks, and using rooting compounds is not necessary. However, using rooting compounds such as IBA-K may accelerate rooting and improve the overall uniformity.
Nepeta performs best in a well-drained media with a pH between 6.0 and 6.6. When irrigating, water thoroughly and let plants dry out slightly between waterings. ‘Blue Ice’ is a light to moderate feeder, requiring only modest amounts of fertility. Generally, when planting nepeta, I incorporate a controlled-release fertilizer into the growing media at a rate equivalent to 1 lb. of nitrogen per yard of growing medium. Another method to deliver fertilizer to this crop would be using a constant liquid fertilizer program, Á delivering 100-150 ppm nitrates to the crop at each watering. To prevent crown and root rots and to ensure that plants get off to a healthy start it is beneficial to drench them with a broad spectrum fungicide such as Banrot (The Scotts Co.) or a combination of Subdue (Syngenta) and Cleary’s 3336 (Cleary Chemical) following planting.
There are relatively few diseases affecting the production of nepeta, and seldom does significant plant injury or losses occur. Crown and root rots are likely to appear when plants are grown under wet conditions. I have also seen Botrytis outbreaks in the foliage, usually in situations where there is a dense plant canopy, little air movement and water remaining on the leaves for long durations. In Southern climates, where the conditions are often hot and humid, growers have also observed the presence of the bacterial pathogen Pseudomonas. When these conditions are present, applying copper-based fungicides such as Phyton 27 (Source Tech. Bio) or Camelot (Whitmire Micro-Gen) on a preventative basis may be helpful. Carefully discard all Pseudomonas-infected plants to prevent the spread of this disease, as bacterial diseases cannot be controlled.
Nepeta is frequently used as a food source by several insects. None of them cause any significant injury, but their presence may not be appreciated by growers or consumers alike. The most common pests of nepeta include aphids, leafhoppers, slugs, snails, spider mites and whiteflies. Through routine scouting the occurrence of these insects can be detected early and treated on an “as needed” basis.
Of these pests, spider mites are the most difficult to control, as they feed on the undersides of the leaves where it is difficult to get adequate coverage with insecticides. To enhance your coverage, deliver an adequate volume of miticide using sufficient spray pressure (200-300 psi), which causes the leaves to turn or lift up during the application, allowing coverage of the chemical to the lower leaf surfaces. Use of spray adjuvant or spreader/stickers such as Capsil (Scotts) or Latron B-1956 (Britz Fertilizers) will also help these chemicals coat the leaf surfaces, increasing the likelihood of spider mites coming in contact with the pesticide being applied. I have also had luck combining ovicides such as Hexygon (Gowan) or Ovation (The Scotts Co.) with more traditional miticides such as Avid (Syngenta) or Floramite (Crompton).
Producing flowering ‘Blue Ice’ out of season is relatively easy, provided a few guidelines are followed. Nepeta do not require vernalization for flowering, but providing a cold treatment to plugs or small containers for 6-9 weeks at 40° F will enhance their flowering uniformity and reduce the time it takes to reach flowering. ‘Blue Ice’ requires long days to promote flowering. Growers can provide photoperiods (day length) of 16 hours by extending the day if necessary or use a four-hour night interruption during the middle of the night, providing a minimum of 10 foot-candles of light at plant level. The time it takes to reach flowering depends on the growing temperature after the plants are placed under long-day conditions. Plants grown at 64° F will flower in approximately seven weeks, while plants grown at 68° F will flower in as little as five weeks.
Nepeta x faassenii ‘Blue Ice’ is a new introduction this year and is being marketed as a Proven Selections branded plant. Currently, liners of ‘Blue Ice’ are only available from EuroAmerican Propagators. There is limited availability of this variety this year; expect wider availability in the near future as more licensed Proven Winners/Proven Selections propagators add this variety to their propagation programs.