| ________Rooted cuttings should be pinched at time of transplanting, and again once lateral
shoots are 3-4” long, in order to produce well-branched plants. We are in the process of
completing experiments with growth regulators on all four cultivars. We have trialed three
different production regimes. Rooted cuttings placed directly into one gallon containers were
finished and in flower 8-10 weeks after transplant. Rooted cuttings were also placed into 4” pots,
and then transplanted 4 weeks later into 2 gallon containers. These were finished and in flower
10 to 12 weeks after transplant. We also transplanted five rooted cuttings into 10” hanging
baskets. Only rooted softwood cuttings (vs. semi-ripened wood) should be used for this purpose.
‘Wine Red’ and ‘Royal Blue’ appear most amenable to basket culture of the four cultivars, but
baskets were no longer attractive after five months
________We have successfully grown all four cultivars in 5:4:1 (by volume) aged pine bark:
coconut coir dust: coarse sand, modified subsequently to 25% total volume with coarse perlite, as
well as the same substrate without perlite added. The substrate was amended with 5.0 kg·m -3
17N-2.3P-10K Osmocote (Scott’s, Milpitas, Calif.), 4.2 kg·m -3 dolomite and 1.2 kg·m -3
Micromax (Scott’s, Milpitas, Calif.). A pH of 6.0 to 6.5 is essential. Substrate pH in excess of
7.0 results in chronic iron deficiency symptoms.
________If allowed to become potbound, all four cultivars of I. cyaneum exhibit “hard”, woody
growth, and drop their lower leaves. Such plants can be renovated by cutting the stems back to a
few nodes, disrupting and pruning the dense root mass, and transplanting into fresh substrate.
________Trial blocks of all four cultivars were established at the National Germplasm
Repository, Miami, Fla from plants established in 2 gallon containers in 2001 in both amended
(ten yr old aged compost from vegetative solid waste) and unamended soil. The plants in
amended soil reached 5’ in height in less than a year and have been in continuous bloom. The
plants in unamended soil (pH = 8.5-9.0) are consistently iron deficient and flower only
sporadically.______
________In the landscape, all four cultivars of I. cyaneum should be situated in full sun, on soils
amended
with organic matter, and fertilized regularly. In sites with light levels less than full sun,
stem
internodes elongate detrimentally and flowering decreases. Once each year the plants should
be
cut back to ½ to 2/3 of their height. The soil should be evenly moist throughout the growing
season; irrigation can be reduced during the winter.
________Pest and disease problems are few. Tobacco (Manduca sexta (Linnaeus)) and
Tomato (Manduca quinquemaculata (Haworth)) hornworms will feed on I. cyaneum, and
occasional light infestations of various homopteran insects have been encountered. I. cyaneum
is potentially susceptible to tobacco mosaic virus (TMV), and nursery workers who use tobacco
should not propagate the plants, or should at least wash their hands with 95% EtOH before doing
so.
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