Festuca glauca ‘Boulder Blue’ By Paul Pilon

Festuca ‘Boulder Blue’ is an outstanding cultivar of ornamental grass. Although it is new to the commercial perennial trade, Boulder Blue was actually selected more than 25 years ago by plantsman Ted Keuttel of Golden, Colo. This cultivar has been produced regionally for quite some time but just recently became available to growers throughout the country. The main improvements of this variety over the most commonly grown cultivar ‘Elijah Blue’, is definitely its improved leaf color. Elijah Blue can be best described as having a powder blue coloration, while Boulder Blue has a deep metallic blue appearance. Growers have observed variations regarding the intensity of the blue coloration while being produced in various regions of the country.

Commonly known as fescue, Festuca is hardy in USDA Zones 4-9. Usually considered an evergreen in most parts of the country, Boulder Blue provides color, form and texture to the landscape. Festuca is generally an easy-to-grow plant but is somewhat particular about temperature and moisture. It does not perform well during hot muggy summers, extremely dry-hot conditions or periods of excessive rainfall or when produced in heavy soils. Festuca is considered a clump-forming, cool-season grass. It performs best when grown in full sun, and once established, it shows some level of drought tolerance.


Like most fescue cultivars, it is recommended to propagate Boulder Blue by divisions. Plants started from seed will take much longer to finish and will show great variability of plant color, habit and vigor, as the seedlings are not true-to-type (genetically slightly different from the parent plants). Divisions can be done successfully throughout the year, but commercially, most producers propagate their fescue early in the spring. The size of the division will vary depending on the size of the desired finished container. For example, the starting material for a 21-cell plug will vary dramatically from the material needed for a 1-gal. container.

Care should be taken when planting the division into the finished container. Pay particular attention to ensure the potting substrate comes into good contact with the propagule, and do not let the medium dry out until the division is well rooted. If the proper conditions exist, Boulder Blue will root easily after the division.


Most growers will transplant divisions or plugs into their finished containers. When planting divisions, as mentioned previously, it is important for the division to be in good contact with the potting medium and to properly manage the initial moisture levels. Try to avoid air pockets between the division and the medium, and do not provide conditions that will lead to water stress. Divisions are most commonly used during early spring, while plugs are used for transplanting throughout the production season. While transplanting plugs, try to avoid planting them too high or too low — always plant to match the original soil line of the plant.

It is important to keep the root zone of newly potted grasses moist, but not wet, until they become established. Once they are fully rooted, Festuca can be allowed to dry out more fully between waterings.

Festuca will perform well in a wide range of potting mediums. It is recommended to use a media with adequate drainage and water-holding capacity. Festuca are light to moderate feeders and perform best when either a constant liquid fertilization program is used, feeding at rates of 50-100 ppm nitrate, or a controlled release fertilizer is incorporated at a rate equivalent to 1-11/2 lbs. of nitrogen per yard of growing medium. The pH of the growing medium should be maintained within the range of 6.0-6.5.

For plant establishment, it is recommended to maintain average temperatures of at least 65¡ F. Once they are established, grow Festuca with 55-70¡ F day temperatures, and night temperatures between 55-60¡ F. At these temperatures a 1-gal. pot can reach finished size from divisions or 21-cell plugs in 7-9 weeks. Boulder Blue should be produced under high light levels with a minimum of 5,000-6,000 foot-candles. Lower light levels or areas of partial shade are still adequate for plant growth and development. Since this cultivar forms nice, compact clumps reaching 8-10 inches tall, controlling the plant height has never been an issue.

Pests & Diseases

Insect problems are generally a rare occurrence with commercial Festuca production. Aphids are the only insect that has on occasion become problematic. They seldom cause significant plant damage and can be controlled relatively easily using contact insecticides labeled for aphid control. One of my favorite contact controls is to spray a combination of insecticidal soap and a pyrethroid-based insecticide such as Decathlon 20 WP. Generally, one application is adequate for aphid control. However, depending on the degree of infestation and the level of spray coverage achieved, a second spray application may be necessary.

There are a couple of problems associated with plant pathogens. Most commonly, the original problem is actually cultural in nature and in many instances can be prevented. One common problem can be observed within two weeks of planting. As mentioned earlier, it is essential for the division to be in good contact with the potting medium when it is planted and for the moisture levels to be properly monitored. Many times after planting, growers will observe the plants are not actively growing and actually appear to be turning brown. Many of the clumps continue to go down hill and ultimately die. Using fungicide drenches to slow down or stop the deterioration of the clumps will most often only have a limited effect.

Another common observation is very similar to what often happens at planting, but occurs after the plants are well established. The clumps within the pot often become lopsided, dying out in spots, or dying out completely. This problem is often caused by one or more of the following factors: high salt levels in the media, too much irrigation, poor physical properties of the media, or the crop has been grown in the same pot/medium for too long. Any of these conditions could lead to plant stress and the onset of root rot pathogens. Try to pick a medium that has good water-holding and drainage characteristics and will not deteriorate or settle over time. Monitor irrigation practices and fertility levels on a regular basis, making adjustments accordingly. When possible, do not hold Festuca in a pot for an extended period of time (12 months or more). When these measures are taken, most of these problems can be prevented.


Festuca Boulder Blue is available as a plug or finished container from many reputable companies across the country. Bare root availability of this cultivar will be limited for the next couple of years.

Paul Pilon

Paul Pilon is head grower at Sawyer Nursery, Hudsonville, Mich. He can be reached by E-mail at pjpexpress@juno.com.

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