November 2013 Culture

Perennial Solutions: Heliopsis ‘Sunburst’ By Paul Pilon

Many growers, landscapers and consumers are drawn to plants with variegated leaves. When interesting foliage is combined with a brilliant display of blooms, the interest level and demand quickly escalates.

Heliopsis ‘Sunburst’ provides beautifully intricate cream and green variegated foliage and produces cheerful, golden yellow daisy-like flowers in the summer. Unlike other variegated heliopsis, ‘Sunburst’ is propagated by seed and blooms during the first growing season from early sowings.

In the landscape, ‘Sunburst’ grows best under full sun and forms beautiful clumps reaching 28 inches tall by 24 inches wide at maturity. It produces numerous bright yellow daisy-like flowers all summer long atop its attractive variegated foliage. Heliopsis performs well in throughout USDA Hardiness Zones 4 to 9.

Heliopsis can be used in mass plantings, as accent plants in beds and borders, in patio pots and combination planters. Additionally, they can be grown as a cut flower and to attract butterflies into the landscape. With its ease of production, variegated foliage, and bright blooms, ‘Sunburst’ would make a great addition to most perennial programs and can be marketed with or without flowers.

Propagation

Heliopsis ‘Sunburst’ is easily propagated by seed. Sow two seeds per cell in 288 or larger sized plug trays. Cover the seeds lightly with germination mix or medium grade vermiculite to help keep the seed moist during germination. Light is beneficial for germination; avoid covering them too deeply.

After sowing, moisten the trays and move them into a warm environment where the temperatures can be maintained at 68 to 74° F for germination. Many growers utilize germination chambers to provide uniform moisture levels and temperatures during this stage. Using germination chambers is optional as ‘Sunburst’ will successfully germinate in a properly managed greenhouse. As with most variegated perennials, there will be a small percentage of plants which are non-variegated; these can be discarded.

Keep the media moist, but not wet, during germination (moisture easily observed on the surface). The seeds should be germinated in seven to 10 days. Following germination, reduce the moisture levels somewhat, keeping the media surface wet to the touch, but not saturated.

Reduce the production temperatures to 65 to 68° F once the true leaves are present.

Fertilizers are usually applied when the true leaves are present, applying 100- to 150-ppm nitrogen every third irrigation or 75 ppm with every irrigation using nitrate-nitrogen sources with low phosphorus levels. When plugs are grown at 65° F, they are usually ready for transplanting in seven to eight weeks.

Production

‘Sunburst’ is well suited for production in intermediate (1 gallon) to large-sized (2 gallon) containers. Heliopsis perform best when they are grown in a moist, well-drained growing mix. Many commercially available peat- or bark-based growing mixes work well provided there is good water holding ability and adequate drainage. When planting, the liners should be planted so the original soil line of the plug is even with the surface of the growing medium of the new container.

To improve lateral branching, increase the number of flowers, and improve fullness in containers, it is beneficial to pinch them two weeks after transplanting; large container sizes may require two pinches. Pinching will increase the production time by approximately two weeks for each time they are pinched.

During production, heliopsis prefers to be kept moist, but not wet. Water them as needed when the plants are young and becoming established. As the crop matures and approaches flowering, more frequent irrigations will need to be applied.

Heliopsis ‘Sunburst’ requires light to moderate fertility levels. Growers using water-soluble fertilizers apply 75- to 125-ppm nitrogen with every irrigation or use 200 ppm as needed. Controlled-release fertilizers are commonly applied as a top-dress onto the media surface using the medium recommended rate on the fertilizer label or incorporated into the growing medium prior to planting at a rate equivalent to one pound of elemental nitrogen per yard of growing medium. The pH of the media should be maintained between 5.8 and 6.4.
If growth control is necessary, several plant growth regulators are effective at reducing stem elongation of lavenders. Foliar sprays of 3-ppm uniconazole (Concise or Sumagic) or 2,500-ppm daminozide (B-Nine or Dazide) can be applied. One or two applications applied seven days apart should provide sufficient control.

Insects and Diseases

Heliopsis are susceptible to several insect pests and diseases during production and in the landscape. Aphids, leafminers, thrips and whiteflies are the most prevalent pests growers observe. The primary pathogens that infect false sunflowers are leaf spots (Ascochyta, Cercospora, Phyllosticta and Septoria), powdery mildew and rust. Of these diseases, powdery mildew is the most prevalent. Growers can detect the presence of insects and diseases using routine scouting programs and determine if and when control strategies are necessary.

Scheduling

With its attractive foliage, heliopsis ‘Sunburst’ can be marketed as a foliage perennial or in full flower. Growers producing it in small container sizes or in combination planters often sell plants that are not in bloom. However, if flowering is desirable, ‘Sunburst’ can be easily produced and marketed in full bloom for late spring or early summer sales.

Heliopsis ‘Sunburst’ does not require vernalization for flowering. Plants will easily bloom whether or not they have been over-wintered (received a cold treatment). When growing them in large container sizes, it is best to bulk up the plants prior to forcing. The bulking period is usually provided in the late summer or early fall the year before they are to be sold. The length of the bulking period depends on the size of the pot; allow a minimum of six weeks for bulking prior to overwintering.

Heliopsis are obligate long day plants and will not flower when the natural day lengths are less than 14 hours. In fact, they require long photoperiods for them to grow and flower; the plants remain compact and do not elongate under naturally short days. Photoperiodic lighting (day extension or night interruption) will effectively promote active growth and flowering when the day lengths are naturally short.

The time to bloom after vernalization and the proper photoperiod is provided is a function of temperature. ‘Sunburst’ takes approximately 11 to 12 weeks to flower when they are grown at 68° F. If the plants have been pinched to promote branching, add two to three additional weeks to the production time for each time the plants have been pinched. Non-flowering containers can be grown in less time; allow six to seven weeks for 1-gallon sized containers.

Availability
Heliopsis ‘Sunburst’ was brought to the market by Sahin Seeds. Plugs are available from Walters Gardens Inc. (www.waltersgardens.com) and Swift Greenhouses (www.swiftgreenhouses.com).