May 2013 Culture

Crop Culture Report: Penstemon Riding Hood Series By Susan Liou

Originating from the Rocky Mountains and the Southwest United States, the penstemon Riding Hood series has exceptional winter hardiness (Zone 3, -4¡ F) that is a rarity among penstemons. Bred by Molter BV, the first variety in this series was introduced in 2001, the 'Red Riding Hood' (PP). After seeing its wonderful characteristics and success through trials, Molter BV continued its breeding program and in 2010 introduced a total of seven colors to complete this series — all with vibrant flowering colors, proliferous flower count, compact growth habit and, most importantly, winter hardiness for the avid gardeners in the Northern states.

Series Characteristics

The penstemon Riding Hood series is a spring-flowering perennial penstemon that comes in seven attractive colors: Red, Blue, Deft Blue, Hot Pink, Lavender, Marble-Cream and Purple. They are the perfect spotlight in garden beds, perennial borders or in decorative containers on the patio. Superior basal branching and thick, glossy leaves will keep these penstemons very manageable. Plants can grow to 18 to 22 inches tall with up to 42 inches spread.

Butterflies and hummingbirds can't help but be attracted to the bell-shaped flowers that cover the slender flower stems. Deer, however, will stay away from them. Flowering will start in early spring and continue through summer into fall. An additional retail feature of penstemon Riding Hoods is that the plants will flower in their first year. Little maintenance is required once the plant is established.

Temperatures

Riding Hood penstemons love the sun and thrive in warmer temperatures. In the winter months, their cold hardiness Zone is 3 through 5, down to -4¡ F. A regular watering and feeding schedule is sufficient during the first growing season to develop an extensive root system. Fertilization also enhances flower color and leaf development. Once established, plants require only occasional watering and very low maintenance. Though this series is tolerant to drought conditions in warmer months, plants should not be allowed to get bone dry as wilted leaves do not recover well.

Crop Scheduling and Timing

Growing an attractive penstemon Riding Hood is easy. Unrooted cuttings of this series are available from Hishtil Nurseries of Israel through major brokers. On arrival, cuttings should be stuck immediately in 103-cell or larger trays. As plants root easily, rooting hormone dip is not necessary. Keep soil sufficiently wet with regular mist/fog until rooting is visible, then remove from mist to allow young plants to develop.

Likewise, rooted liners ready for transplant are available from all major propagation nurseries throughout North America. For early spring retail in 1-gallon containers, plugs should be transplanted in January with one plug per pot and allow 12 weeks for plants to establish full body. For a 2-gallon container, one should transplant in September with three plugs per pot and allow 30 weeks to finish. During development, plants do not require pinching, PGRs or vernalization. In fact, young plants that are not vernalized with cold conditions will produce fresh branch growth once transferred to outdoor conditions.

Penstemon Riding Hoods require day and night temperatures of 70¡ F and 50¡ F, respectively. Once temperature rises above 50¡ F at night and flower buds are apparent, plants should be moved outdoors to capture higher light intensity to promote floral development. Prolonged production under plastic or glass cover can lead to overstretching and faded flower colors.

Pest and Disease

Under full sun conditions, penstemon Riding Hoods are generally disease and pest free. When plants are grown under stress (in shade or cold snaps as a young plant), they may be more susceptible to leaf spot and mildew. When outside temperature rises above 50¡ F, plants should be transferred outside to promote more vibrant flower color development.

Crop Culture Report: Penstemon Riding Hood Series