October 2013 Culture

Perennial Solutions: Campanula portenschlagiana ‘Miss Melanie’ By Paul Pilon

There are several types of campanula available today. Many of them have become popular and are widely produced. One of the well known, but not the most popular species of campanula, is C. portenschlagiana.

Recently, Florensis brought Campanula portenschlagiana ‘Miss Melanie’ to the market. ‘Miss Melanie’ has a compact growth habit and produces loads of attractive violet-blue bell-shaped flowers atop attractive green foliage. A great feature of this plant is its extended bloom time; flowering occurs for several weeks, which is longer than many campanula cultivars in production today.

‘Miss Melanie’ forms low growing floriferous mounds reaching only 6 to 8 inches in height when blooming. Flowering begins in the late spring and continues through the majority of the summer. Campanula portenschlagiana performs well across USDA Hardiness Zones 5 to 7 and AHS Heat Zones 7 to 1. With its attractive compact habit, it is suitable for use in rock gardens, edge plantings, as a small scale groundcover or in patio pots. Like other bellflowers, ‘Miss Melanie’ is deer and rabbit resistant.

Bellflowers are among the most popular of perennials. With its compact size, flower power, shelf appeal and ease of production, growers should consider adding ‘Miss Melanie’ to their late spring perennial offerings.

Propagation
Campanula ‘Miss Melanie’ is vegetatively propagated from tip cuttings. Moisten the growing mix or stabilized growing media prior to sticking the unrooted cuttings (URCs). Dipping the basal ends of the cuttings in a 1,000-ppm IBA soluble salts solution prior to sticking will improve the uniformity of rooting and decrease the rooting times slightly.

Place the cuttings under a high misting regime for approximately the first few days of propagation. Rooting occurs best when they are propagated under high humidity levels (90 percent relative humidity) with minimal misting. After the first few days, avoid providing too much misting or rooting may be inhibited and diseases can develop. Conversely, avoid under-misting and allowing the cuttings to wilt as rooting will also be adversely affected.

It is beneficial to apply water-soluble fertilizers using 75- to 100-ppm nitrogen at each irrigation beginning one week after sticking the cuttings. During propagation, growers may need preventative control strategies, such as using beneficial nematodes Steinernema feltiae, for controlling fungus gnat larvae which often feed on campanula during propagation.
Gradually reduce the amount of misting as roots become more developed. Remove the misting altogether once they are rooted and remain turgid throughout the day. The cuttings are usually rooted in approximately three to four weeks with soil temperatures ranging from 68 to 72° F. It is recommended to pinch the cuttings one to two weeks after the misting has been removed to promote branching. Liners take approximately eight to 10 weeks from sticking to become fully rooted and ready for transplanting.

Production

Campanula ‘Miss Melanie’ is best suited for production in one gallon or smaller sized containers. It performs best when grown in moist, well drained growing mixes; many peat and bark based growing mixes work well. When transplanting, the liners should be planted so the original soil line of the liner is even with the surface of the growing medium of the new container. Pinching is not usually necessary unless the liners were not pinched prior to transplanting. The best quality is achieved when they are grown in production facilities with high light intensities.

Dalmatian bellflowers perform best when grown with light to moderate fertility levels. Growers using water soluble fertilizers commonly provide 75- to 125-ppm nitrogen plus micronutrients with each irrigation or 150- to 250-ppm nitrogen as needed. Controlled-release fertilizers can be incorporated into the growing mix before planting using the equivalent of 1 pound of elemental nitrogen per cubic yard of growing mix or top dressed using the medium labeled rate. During production, maintain slightly acidic conditions; pH: 5.8 to 6.3.

Campanula should be grown under “average” irrigation regimes. Keep them slightly moist, but not wet during production. Root zones which remain consistently wet tend to develop crown and root rots. Conversely, bellflowers which are allowed to become overly dry, usually have reduced quality attributes and delayed flowering. When irrigation is necessary, water them thoroughly then allow the soil to dry slightly between waterings.

Campanula ‘Miss Melanie’ has a compact growing habit and will not usually require height control strategies. However, under certain circumstances, such as when they are grown at high plant densities or with ‘luxury’ nutrient levels, it may be necessary to implement height management strategies. If production space is available, the most effective strategy for reducing stem elongation is to provide adequate spacing between the plants. If toning is necessary, the plants can be sprayed with 2,500-ppm daminozide, 30-ppm paclobutrazol or 5-ppm uniconazole; one to two applications should suffice.

Insects and Diseases

There are only a few pests and diseases that attack campanula. Aphids, spider mites, Western flower thrips and whiteflies are the most prevalent pests. Of these insect pests, aphids occur the most frequently and can occasionally be observed feeding on the growing tips of the newest shoots. Botrytis, Colletotrichum, Pythium and Rhizoctonia are the primary diseases that attack bellflowers. Routine scouting is helpful for detecting the presence of insects and diseases early and for determining if and when control strategies are necessary.

Scheduling

Campanula ‘Miss Melanie’ can be scheduled to be marketed in bloom from the mid-spring to mid-summer. ‘Miss Melanie’ is a cold beneficial plant. To obtain the most uniform flowering and the most blooms per plant, it is best to provide vernalization to either large liners or plants in the final container sizes. Additionally, plants that have been vernalized will flower approximately two to three weeks faster than unvernalized ones. When possible, I recommend growers consider using vernalized materials for early spring shipments to allow them to produce flowering plants quicker and switch to unvernalized materials for sales later in the year.

Campanula portenschlagiana are day-neutral plants. They will flower under any photoperiod and can be forced into bloom under natural day lengths. The time to bloom depends largely on production temperatures and whether they are vernalized or unvernalized prior to forcing. With 24-hour average temperatures of 65° F, vernalized plants will flower in approximately seven to eight week; whereas, unvernalized plants will flower in 10 to 11 weeks at these temperatures.

Availability

Unrooted cuttings of Campanula portenschlagiana ‘Miss Melanie’ are available to growers through Green Leaf Plants (www.glplants.com). Rooted liners are available from Green Leaf Plants, Pacific Plug & Liner (www.ppandl.com) and other reputable perennial plug producers or plant brokers.