The genus Strobilanthes (Mexican petunia), a large and variable group, includes only one species com­monly grown as a house plant, S. dyer anus (Persian shield). This is an erect-growing and much-branching shrub, which is an attractive foliage plant when young but becomes faded and straggly as it ages. Plants are best discarded when more than 15-18 in­ches high. The soft-woody, hairy stems of strobilantheses carry pointed-oval leaves up to 6 inches long and 2 inches wide on 1-inch-long leafstalks. The finely tooth-edged leaves have a dark green upper surface with a pro­nounced bluish, metallic sheen that does not quite extend to the green margins; the underside is deep purple. Pale blue flowers (which are seldom produced on young plants indoors) are funnel-shaped and 1 1/2  inches long. They rise in small spikes from leaf axils in late summer.


Light    Give    these    strobilantheses bright, filtered light all year long.

Temperature Normal room tem­peratures are suitable. A strobilanthes cannot tolerate temperatures below about 55°F.

Watering Water actively growing plants moderately, giving enough at each watering to make the potting mixture moist throughout and allow­ing the top half-inch of the mixture to dry out before watering again. En­courage plants to have a short winter rest by giving only enough water to prevent the mixture from completely drying out during a two- or three-month rest period.

Feeding Apply standard liquid ferti­lizer to actively growing plants every two weeks.

Potting and repotting Use an equal-parts combination of soil-based potting mixture  and leaf mold. Move plants into pots one size larger whenever roots appear on the surface of the mixture (an in­dication that the roots have begun to fill the pot). When a plant has reached the 6-inch pot size, it is probably past its prime, or nearly so, and should be replaced by a young specimen. As they age, these plants lose much of their leaf coloring and become leafless at the bottom of stems.

Propagation Propagate in spring by 2- to 3-inch-long stem cuttings that have been trimmed to just below a leaf. Remove the lower leaf to pre­vent possibly harmful contact be­tween a leaf and the potting mixture, and dip the bottom of the cutting in hormone rooting powder. Plant each cutting in a 2- or 3-inch pot contain­ing a moistened equal-parts mixture of peat moss and coarse sand or perlite, and enclose the whole in a plastic bag or heated propagating case. Stand it in bright filtered light at a temperature of 65°-70°F until re­newed growth indicates that rooting has occurred (probably in three to five weeks). Uncover the rooted cutting, and begin to water (giving only en­ough to make the mixture barely moist) until 2-3 inches of new top growth has developed. Thereafter, begin to water normally, and start regular feedings as recommended above. About two months after the beginning of the propagation process move the plant into a slightly larger pot of the potting mixture recom­mended for adult plants, and treat the young strobilanthes in exactly the same way as a mature specimen.

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