NC State Extension

Helianthus ‘Sun4U Bicolor’

Helianthus 'Sun4U Bicolor'

Trial: Annual

Year Trialed: 2008

Good Qualities:

Great bi-color (6), even the stems have pretty coloration; Very uniform height or flowering time (4), cut all of each color in about 1 week; Did not lose petals as easily as most bi-colors (2); A nice big bloom on strong stem, a few customers especially commented on the lovely bi-color appeal; Easy to grow, nice size bloom; Good germination – harvested 77 stems; Good neck/stem strength and posture, very attractive bloom, good petal overlap; Forward facing head, nice brown center very tactile, ray petals uniform length, nice moderate sized head, plant height and stem diameter generally were more what I like than the ProCuts or Sunrich series planted at the same time and in the same bed; Prolific side shoot production, bicolor was apparent even on underside of petals, stem coloration also attractive, good uniformity in bicolor habit; Tall plant; Love the Van Gough look of this one; The smaller head worked well in arrangements; All Sun4U were perfectly fine, single suns; Very popular bicolor with lots of the oooooh factor; rapid and strong germination; some flowers are up facing which is favored by designers; Blooms a few days ahead of orange types; Flowers mostly in 7-8 inch diameter with secondary flowers being an inch or 2 smaller; Produces usable attractive branches after main stem harvest; An interesting feature of this cultivar is the smaller leaf under the flower, it makes for a very attractive display when bunched as the leaves are below the flower head, flowered earlier than the other bicolor sunflowers that I had planted at the same time; ‘Sun4U Bicolor’ was by far my favorite!!!!; Good stem caliper, early to flower.


None (2); A few blooms were not held erect; Bicolor not appreciated by customers, had to replace with ‘Sunrich’ for a farm stand I sell to, Bicolor also fragile, lost petal in transit much like ‘Joker’ and ‘Moulin Rouge’, ‘Lemon’ and ‘Orange’, very few petals on head, if lost one petal, had to junk flower; Petals tend to bend backward with maturity; Distorted heads, prone to insect damage, I tended to wait until head more open than the Procut Bicolor in order to tell if the petals would all elongate and disk would be uniform shape, i.e. marketable; Stems were very susceptible to breakage, all plants in our trial lost at least one usable stem from breaking; Petal drop at early stage of flowering; I planted too far apart yielding very large heads I could not use in bouquets; The larger flower head didn’t work well in arrangements; I wasn’t impressed with strength of stem or vaselife to grow again; For those interested in only the primary flower, the branching may not be desirable as it makes stripping leaves more difficult; Typical of bicolors is that the petals seem to fall off faster than the traditional yellow and orange petaled sunflowers; While the petals did come off with the slightest abrasion, this new cultivar seemed better than any I have tried to date, certainly far superior to any of the “red” ones, just looking at those seem to encourage petals to fall off, in any event, it is an improvement over other bicolors; Not very uniform i.e. some plants tall and some short, the brown center fades quickly as the flower opens.

Similar Cultivars:

Trial variety 565 (2); ‘Procut Bicolor’ (2), liked this one better; Pro Cut Series; Bicolor, ‘Orange Mahogany’, flowered 5-7 days later than Procut Bicolor; The Sunrich series; Several; There are other bicolor sunflowers, but this is among the best.


Harvested between 8/4-8/20 (direct seeded in the field on May 28); Would be really nice to get some rust resistance in these ornamental sunflowers, this one seemed to be more susceptible to rust or more heavily infected than the ‘Procut Bicolor’ but this was not quantified, rust was a big problem this year since we are growing organically combined with weather conditions this year and my absence during two critical weeks in July; Very attractive in the field, great plant height; Basically a normal cutflower sunflower, created some problems with the wholesale account, this year due to a very cool spring, the sunflower rotations came into flower at about the same time, like everyone, we pick our sunflowers when the first petal is just beginning to lift off, they look pretty similar at this point, the color of the center is about the only thing that looks different – while bunching, it was hard to keep all the different sunflower varieties separate, especially when we were dealing with lower numbers, so we frequently sent out mixed bunches, the retail florist didn’t seem to mind, but the wholesaler did not like the mixed bunches at all!; One large head at 9 in., and one small head at 5.5 in.; Nothing to write home about, not that large headed, not exciting; Seed catalogs list this as a single stem variety, but I found a weak tendency for branching and if the main flower is cut short side flowers will develop; The Sun4U series is a winner but this one is the weakest link; I will definitely look for more seeds for Sun4U Bicolor, great color; Flowered around August 5 (sowed June 11, transplanted to field June 25), flower diameter 7.5 in., not any better than other bicolor (#565).


Kept well if stems were recut under water and then held in a bleach/water solution; Remove leaves; Cut early and used Floralife; We only used plain water; Just from observation this variety seemed to have longer post harvest life; Cut before fully open; Keep the vase solution clean; We always cut our sunflowers into plain warm well water with a splash of bleach…works for us.

See separate postharvest report for results from NC State University postharvest evaluations.

Trial Data

Helianthus ‘Sun4U Bicolor’
Yield (stems/plant) Stem Length (inches) Market Appreciation Rating – Wholesale (1) Market Appreciation Rating – Retail (1) Market Appreciation Rating – Consumer (1) Repeat Again Rating (1) Ease of Cultivation Rating (1) Average Spacing (in2) Average Postharvest Life (days)
Average 1.9 44.2 3.5 3.8 4.1 3.5 4.4 149 9.3
Range of Responses 1-5 24-72 2-5 3-5 3-5 1-5 2-5 36-648 7-14

(1) 1 to 5 scale, with 5 being the best. Market ratings are based on sales to wholesalers, retailers, or final consumers direct.


P.O. Box 618
Conway, WA 98238

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