April 2007

Crop Culture Report: Pentas Bahamas Series By Jack Williams

These heavily flowering annuals thrive in the heat of summer.

When it comes to thriving in the heat, pentas are one of the premier flowering annuals preferred by growers and landscapers. Unlike most bedding plants, whose flowers shrink in size and fade away during high temperatures and humidity, the large inflorescence of the Bahamas series gets even larger and showier in the heat of summer.

Until a few years ago, most pentas were only available from seed, but today they can be sourced as vegetatively produced cuttings often offering a higher level of uniformity and performance in the crop. Production is relatively simple in quart, 5- to 6-inch, gallon and even larger containers. Used alone in monoculture, pentas are an outstanding crop for production and shipping, but they also work well in combination planters. The pentas Bahamas series is available in four colors: Blush, White, Pink and Lavender.

Propagation

Unrooted cuttings should be stuck in a porous, well-aerated rooting medium. Use of a rooting hormone is beneficial, as is bottom heat during rooting. Cuttings take 3-4 weeks to root and get ready for transplant. Direct sticking is also an option, but careful attention must be paid to misting to prevent over-saturation. B-Nine (Chemtura Corp.) can be sprayed during propagation to help prevent stretch. Pinching prior to transplant will also enhance branching and plant shape.

Growing On

Transplant cuttings once a good root system is established and maintain moderately dry soil to encourage root penetration in the media. Keep soil temperatures from cooling during this stage.

Pinch young transplants (if not already done) within 2-3 weeks using a soft pinch to leave as many leaf pairs as desired. Quart pots usually are ideal at two leaf pairs; larger containers with one cutting work well if 3-4 leaf pairs can be left. A single pinch is all that is usually required unless growing large tubs or specimen plants.

Apply PGR sprays like B-Nine at 2,500 ppm as needed to prevent stretching of young growth; this is especially important for smaller pot sizes where plants should not become too tall and top heavy.

Begin fertilization as soon as possible after transplanting. Pentas prefer a moderate feed level (150-200 ppm nitrogen) using complete and balanced fertilizers: 20-10-20 works well in promoting good leaf expansion and branching. As the crop develops, do not allow the soil to dry down as this can result in leaf tip burn.

Pentas are relatively free of insect or disease problems, although, like any crop, a preventive application of a broad-spectrum fungicide at transplant is suggested. Monitor the crop throughout production for pests such as aphids, thrips and whiteflies. Watch for spider mites during late spring.

Schedule this crop for peak performance during late spring and summer. As pentas are best used for the warm season, position them in the greenhouse after the early season cool crops have shipped. Avoid selling during early spring as cool temperatures cause foliage to burn and flower development is restricted (see Figure 1, above).

Success Tips

The pentas Bahamas series is a good garden plant in commercial and home landscape settings. Flower heads are made up of many small flowers that together create large, showy displays even during the warmest days of summer.

When planted in full sun, mulch the ground to preserve moisture and keep the roots cool. Containers need adequate irrigation or they must be large enough to provide good moisture retention and protection from heat. If roots get too warm (higher than 90¡ F), functionality is reduced; water stress is likely to reduce flowering of this crop.

The series is available in both rooted and unrooted cuttings from Ecke Ranch and Ecke's network of Root & Sell propagators located throughout North America.