November 2003

Tiarella ‘Jeepers Creepers’ By Paul Pilon

Growers often consider tiarella cultivars prime candidates for their product mix for shady locations. After all, tiarellas provide interesting, deeply cut foliage with contrasting leaf patterns and extended bloom times, and they are easy to produce. Tiarella ‘Jeepers Creepers’ is no exception. With its large, bold, well-marked foliage, abundance of cream-colored flowers and eye-catching winter contrast, this cultivar is sure to perform well in today’s perennial marketplace.

Tiarella belongs to the family Saxifragaceae, which includes many other popular perennials such as astilbe, berginia, heuchera, heucherella, rodgersia and saxifrage. Like most tiarella cultivars, Jeepers Creepers prefers locations with partial to full shade throughout USDA Hardiness Zones 4-9. It is often grown commercially for containers, mixed containers, cut flowers, borders and mass plantings.

One of the year-round interests this variety offers is the deeply lobed leaves with purple pigmentation along the midribs and veins of the upper leaf surface. In mid spring they produce large, cream-colored flower spikes over an extended period of time. The planting spreads slowly by underground stolons but always maintains its clump-like appearance, reaching a diameter of 1-2 feet across. For fall and winter, the evergreen foliage transforms to an attractive reddish-bronze display, providing a great winter appearance.

Propagation

Jeepers Creepers is a patented variety and currently only propagated by means of tissue culture; self-propagation is prohibited at this time. Tissue culture has allowed this and many other new varieties of perennials to reach the market in a relatively short period of time. Terra Nova Nurseries Laboratories send small plants from tissue culture to several plug producers. These plug producers then grow the plants into various sizes, which are available to commercial growers.

Production

Jeepers Creepers is commonly grown in container sizes ranging from 1 quart to 1 gal. It performs best in a porous potting substrate with both good water retention and aeration characteristics. When transplanting, make sure the top of the plug is level with the potting medium of the new container. Planting too deep will most likely lead to poor plant establishment and possibly even plant mortality caused by crown rots. The root zone should be kept uniformly moist until the roots reach the outside of the root ball. Once rooted, it can dry out partially between waterings.

During the winter months and through early spring, Jeepers Creepers can be produced under natural light levels within the greenhouse. As the spring progresses and outdoor light levels increase (earlier in the South), production sites should have some type of shade applied, ultimately reducing light levels by 35-50 percent. Production under shade will ensure more active growth and less potential for the leaves to become scorched.

Moisture. Tiarellas do not tolerate overly wet conditions, which may cause Pythium or Phytopthora. Additionally, when they are kept too moist over extended periods of time, the foliage may turn slightly chlorite. They can tolerate dry but not drought-like growing conditions. When irrigation is required, I recommend to water tiarellas thoroughly, allowing them to become dry between waterings.

Feeding. Foam flowers are considered to be light to moderate feeders, requiring modest fertility levels and the pH to be maintained at 5.5-6.5. Growers often feed tiarellas through liquid fertilization programs, delivering 50-100 ppm nitrates with each irrigation. My preferred method to address the fertility needs of this crop is to incorporate a controlled release fertilizer at the time they are planted, using an incorporation rate equivalent to 1 lb. of elemental nitrogen per yard of growing medium. For example, a controlled release fertilizer having a 15-9-12 formulation contains 15 percent nitrogen. For each pound of this product, 15 percent (.15 lbs. or 2.4 ounces) is nitrogen. Therefore, it would take 6.67 lbs. of product incorporated into each yard of growing medium to obtain 1 lb. of nitrogen.

Pests. Aphids and whiteflies are the primary insects that feed on Jeepers Creepers. These pests are somewhat difficult to detect early, as the foliage provides adequate cover, making them hard to find until their populations have built up to undesirable levels. Controlling them can be on a preventative basis using chemicals such as Endeavor, Marathon or TriStar. Curative controls can be implemented using contact chemicals such as insecticidal soaps or pyrethroids such as Telstra. Controlling aphids and whiteflies curatively may require two or more applications of insecticides, depending on the level of infestation, the chemicals used, and the spray coverage. In the landscape, black vine weevils may also be problematic.

Diseases. Tiarellas can be produced relatively disease free. Root and crown rots, caused by the pathogens Phytopthora, Pythium and Rhizoctonia, are the primary diseases growers should be concerned about. They are most susceptible to these pathogens when they are over-watered or when grown under cool conditions, such as going into or coming out of winter dormancy. Botrytis is another disease that could become problematic. Botrytis, like Rhizoctonia, often occurs around the over-wintering process but is also likely to occur under dense plant canopies. With good watering practices and adequate air circulation the occurrence of most diseases can almost be negated.

Finish. When transplanting from a 72-cell plug, Jeepers Creepers grown at 65¡ F typically takes seven weeks to finish a 1-gal. container in the summer or 10 weeks during the winter months. To obtain full, flowering tiarellas for spring sales, it is beneficial to plant them during the late summer of the previous season. I recommend transplanting plugs into the desired container during mid to late August, bulking them up before winter, over-wintering them and forcing them to bloom in the early spring. Although vernalization is not required for flowering, production of tiarellas in this manner delivers more blooms on fuller plants that take less time in the spring to reach a marketable size.

Availability

Jeepers Creepers is brought to the industry by Terra Nova Nurseries, Tigard, Ore. It is available to growers most commonly as finished plugs from Terra Nova or other reputable plug producers throughout the country.