Plant of the Month for March, 2012

(Pen-steh-mon her-SOO-tus)

General Information:

Penstemon hirsutus, the hairy penstemon, is a great garden plant for the front of the border. For the rock garden, try Penstemon hirsutus v. pygmaeus which looks just like the larger form, but is only 15 cm (6 inches) tall. The 2.5 cm long flowers are tubular in shape and coloured a pale mauve with white tips. A white flowering variety is available. Flowers open sequentially so that the plant provides a good show for several weeks.  In fall the foliage turns a golden reddish brown providing a continued display.

        

                                        Penstemon hirsutus; photo by Robert Pavlis

Each rhizome produces several stiff stems that stand up well to winds. The stems, leaves and even the flowers are covered with small fine hairs, hence the common name; hairy penstemon.

Some Penstemons can be tricky plants to grow, but this is not true for P. hirsutus which is easy to grow in normal garden soil as well as in dryer sandy soil. Plants like lots of sun and can be quite dry.

P. hirsutus is a perennial, but under less than ideal conditions it may only survive 3 to 5 years. For this reason it is a good idea to deadhead after flowering and to either divide the plant every few years or to allow some seedlings to grow to maturity. If you are growing the variety pygmaeus, some of the seedlings will revert to full size plants, but most seedlings will remain true to form.  

Hairy penstemon is a larval host for the Baltimore checkerspot butterfly while also attracting a variety of beneficial insects and humming birds.  

                 

                                     Penstemon hirsutus; photo by Robert Pavlis

        Life Cycle: perennial

Height: 60 cm (2 ft) [20 cm for var. pygmaeus]

Bloom Time: late spring to early summer

Natural Range: Ontario, Quebec and north eastern US.

        Habitat: Prairie meadow fields and rocky bluffs

        Synonyms: P. pubescens, P. hirsutus var. minimus, Chelone hirsutus 

          

                                            Penstemon hirsutus; photo by Robert Pavlis

Cultivation:

        Light: full sun                               

Soil: normal well draining to sandy and dry

Water: moderately moist to dry                        

 USDA Hardiness Zone: 3b – 8

Propagation: division in spring, softwood cuttings in early summer, semi-ripe cuttings in mid-summer, and seed. Var. pygmaeus comes mostly true from seed.  

Seedex availability (ORG&HPS annual Seed Exchange): available almost every year

G

Sow @ 4°C for 3 months, then place @ 20°C for 3 months.

3

Requires light or the small seeds should be surface sown. See https://www.youtube.com/watch?v=RgkXUSI1GWo&index=1&list=UUJfYCNSWCIuOB2...
Robert Pavlis