Pulmonaria

November 11, 2003 - 11:23

New cultivars make this crop better than ever.

In the past few years, Terra Nova Nurseries has produced a
number of new pulmonaria, focusing on garden-worthiness combined with the appeal
of improved leaf contrast, superior flower size and colors, and powdery mildew
resistance. Patented varieties are virus indexed and produced from tissue
culture.

New flower colors, leaf-shapes and dynamite vigor have
helped to move pulmonaria up the popularity scale. While there is not enough
space to go over each cultivar, here are a few special ones.

'Silver Shimmers' is a low-growing plant with very silver,
long leaves and large blue flowers. The undulating edges and patina give this
plant the shimmering look for which it is named.

'Emerald Isles' has emerald-green leaves with distinct
silver spotting. Tightly clustered pink flowers (which fade randomly to blue)
produce an intense floral display.

'Trevi Fountain' has large, silver-spotted leaves with
profuse hefty, dark blue flowers.

Tissue Culture

These patented varieties originate in tissue culture planted
into 72-cell trays. Plugs are happiest at 65-percent humidity and 65-70° F
until halfway rooted. They can then begin cool down to 55-60° F. Pulmonaria
need to have cool roots, or they will exhibit heat stress and wilting. During
production, keep soil evenly moist; do not allow soil to dry out between
waterings. Due to heavy foliage growth and high water usage, this plant is a
good candidate for sub-irrigation. Use a balanced fertilizer with
micronutrients at 150 ppm constant liquid feed. In the landscape, pulmonaria
can tolerate a fairly wide range of pH, but in small plugs iron and sulfur
deficiencies can occur above pH 5.8. Plants will not hold in plugs very long
before exhibiting stress symptoms like chlorosis and wilting.

Transplanting

Plugs should be transplanted directly into porous soil in
1-gal. pots with a slow-release fertilizer. We recommend a charge of APEX
19-6-12, 6-month microprill formula with minors. Pulmonaria produces thick
fleshy roots that quickly outgrow small containers and induce water and
nutrient stress. Keep the media moist, but ensure good drainage to avoid root
damage. Foliage can wilt at temps above 85° F, but this heat stress should
not induce the grower to exercise the common reaction of applying more water.
Keep the roots as cool as possible, and foliage will perk up again in the
evenings. Keeping plants on the ground will assure the coolest root temps.

Although dormancy is not required for greenhouse production,
an 8-week cold vernalization will promote optimum flowering and plant size.
Transplanting to 1-gal. pots in late summer (August 21st) or in early fall will
allow plants to fully root out before the flowering phase begins in late
winter, producing the fullest pot. After flowering is finished, cut back, and
the plants will begin to fill out with leaves.

Pests and Diseases

Powdery mildew susceptibility -- once a common problem with
pulmonaria -- has been the focus of recent breeding efforts. All of Terra
Nova's recently introduced varieties are mildew resistant in the Pacific
Northwest.

Botrytis can occur on older leaves at soil level under high
humidity conditions. Running a heat/vent dehumidifying cycle, increasing air
circulation and applying fungicides such as Heritage as necessary should keep
this disease under control. Pulmonaria can produce heavy foliage, inhibiting
air circulation around the crown, so thinning may be necessary on older plants.

Aphids are a common occurrence in the greenhouse environment
but are easily controlled with scouting and appropriate pesticide usage.
Marathon II is used here for control.

It is possible to encounter root rots such as Pythium and
Rhizoctonia if the media is not draining well. Addition of perlite or pumice to
the mix will ensure better drainage.

If you use hydrogen peroxide products, keep them away from
pulmonaria foliage, as they have shown a phytosensitivity, which causes brown
spotting of the leaves.

About The Author

Rachel Rodgers is sales manager at Terra Nova Nurseries, Canby, Ore. She can be reached by phone at (800) 215-9450 or E-mail at rachel@terranovanurseries.com.

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