Photo courtesy of Cultivaris
Rehmannia, or “Chinese Foxglove,” is a rarely encountered genus in our industry — but not for lack of showiness. The large, foxglove-like flowers appear all summer long and are quite attractive, but are usually on tall, rather lax and floppy spikes above large leaf rosettes.
Not so for the brand-new ‘Crouching Tiger’! This truly different selection is a significant upgrade for the entire genus and opens the door to mainstream cultivation. The compact, flat rosettes are made of firm, corrugated, glossy dark-green foliage; after a cool period in winter, stout and sturdy flower spikes rise above the foliage, reminiscent of little Christmas trees. From April onwards, beautiful pure-white flowers with golden, purple-tigered throats appear in abundance.
Production Flowering Rehmannia is a rosette-forming herbaceous perennial that requires a chill period followed by long days to flower. Without a chill period, flowering will be only sporadic and erratic — but once flower initiation has been triggered by 8 weeks of cool temperatures, the plants will flower all season long, from April to October. Temperature Best grown from tissue-culture liners, which should be potted up in a well-drained standard soil mix between August and October; quart pots would be the minimum size, gallons would require a longer bulking period or three liners per pot. ‘Crouching Tiger’ should be given 6 to 8 weeks at 65-70° F to bulk after potting. Once the foliage rosette has covered and extended beyond the pot surface, the plants should be given at least eight weeks of cool, frost-free temperatures, e.g. 45-50° F, together with winter pansies. Flower spikes will appear with increasing daylength and temperature in spring at temperatures between 60-65° F. Watering ‘Crouching Tiger’ should be kept moderately moist at all times. Due to the firm, dark-green, glossy foliage and tight habit of the leaf rosette, watering from above can lead to Botrytis infection, so subirrigation is recommended. Waterlogged soil should be avoided, since this leads to Pythium and other root diseases. Fertilizer Rehmannias are not heavy feeders; regular and moderate doses of a standard bedding plant fertilizer are usually adequate. At high pH levels, iron deficiency can result in yellowing and chlorosis. When planting mixed combos with ‘Crouching Tiger,’ mixing some slow-release fertilizer into the soil media is recommended. Managing growth ‘Crouching Tiger’ is naturally compact and does not require PGR treatments whatsoever. Consumer info ‘Crouching Tiger’ is great in containers, especially in mixed combos, in which the stout, pyramidal flower spikes provide a nice backdrop for other, more bushy or trailing bedding plants. During the course of the summer, the first flower spikes will be spent and can be removed; lateral shoots will continue the floral display throughout the season. Zone 8 hardy, ‘Crouching Tiger’ can survive light frosts outdoors and will spread by underground stolons into larger clumps.