May 2002

Forget-me-not as a Potted Plant By Meriam Karlsson

During the Victorian period, flowers were associated withemotions, strengths or moral qualities. Several legends in the naming of theflower forget-me-not suggest everlasting friendship, remembrance and eternallove. These correlations are still strong, and forget-me-not is often requestedto acknowledge, celebrate or commemorate romance, appreciation orcompanionship. Forget-me-not is also the state flower of Alaska and, therefore,generates additional local demand from many visiting tourists, hotels, restaurantsand public establishments.

Forget-me-not is a familiar plant to gardeners and has beengrown for years in borders or groundcovers. The flowers are less than one inchin diameter and open in succession on a curled spike or cyme inflorescence. Aseach flower withers, a seedpod is left behind. The curled flower spikesresemble the shape of a scorpion and sometimes the common name “scorpiongrass” is used instead of forget-me-not. The delicate flowers are usuallyblue with a lighter eye. Flowers in white or soft pink occur naturally and arealso available.

The scientific genus name of forget-me-not is Myosotisbecause the leaves in some species look a lot like the ears of a mouse. TheMyosotis species are biennial or perennial and grow naturally in moist, shadedor partly shaded areas. True forget-me-not (Myosotis scorpioides) is ashort-lived perennial, while the most commonly cultivated species is thebiennial garden or woodland forget-me-not (Myosotis sylvatica). The gardenforget-me-not has leaves that are 2-3 inches in length and grows to a height of6-12 inches. Myosotis alpestris is similar to M. sylvatica, and it is difficultto distinguish the two species. Seeds of forget-me-not are sold under bothnames, although most M. alpestris is likely M. sylvatica.

Forget-me-not as a cut flower is best-suited for smallfloral pieces, miniature nosegays, corsages or chaplets for the hair. Othermarketing opportunities include flowering potted plants. Seed is available forvarious cultivars such as ‘Snowsylva’ (white),’Rosylva’ (pink), ‘Bluesylva’ (mid-blue), Bobo series(blue), ‘Compindi’ (deep blue), ‘Indigo’ (blue),’Miro’ (mid-blue), ‘Musik’ (deep blue) and’Victoria’ (azure blue). Bluesylva and Victoria have, under ourgrowing conditions, been naturally compact with profuse flowering. The Boboseries and Indigo have longer-flowering shoots than Bluesylva but still makenice plants in 4-inch containers. Compindi and Miro are short, ball-shapedplants with heights of six inches, while Musik grows to a height of 10 inches.Snowsylva and Rosylva are suitable to meet the demand for white and pinkforget-me-nots.

Propagation and early development

Germination takes 8-14 days at 68-72° F. Information onlight requirements for germination varies in the literature; we have hadexcellent germination of uncovered seed under approximately 500 foot-candles(fc) for 16 hours each day. A cold treatment or vernalization significantlypromotes or is unconditionally required for flowering in biennials and manyperennials. Most herbaceous perennials sense vernalization at temperaturesbetween 32 and 45° F. For low temperatures to be effective, plants need toremain active; therefore, low light is required during vernalization. Asuggested level is 25-50 fc. The minimum required period of vernalizationvaries from a few days to several weeks and depends on species, cultivar andphysiological age of the plant.

Cold treatment

Seeds of several cultivars (Bobo series, Indigo andVictoria) were germinated, and seedlings Á were grown at 68° F,approximately 500 fc (100 µmol m-2s-1) for 16 hours and fertilized fromthe first true leaf stage with 100 ppm nitrogen from a complete fertilizercontaining micronutrients. The plants were transplanted into 4-inch pots filledwith a peat-lite medium. Six weeks after seeding, the temperature was droppedto 42° F. Irradiance was 100-125 fc (20-30 µmol m-2s-1) for 16 hours daily.To determine the vernalization requirement, plants were moved from 42° Fafter three, six, nine or 12 weeks. Recommended environmental conditionsfollowing the cold treatment are similar to those of pansy production. Plantswere, therefore, moved to 60° F, 16 hour day length and 750-800 fc (8.6 molday-1m-2). Increasing the fertilizer rate following the cold treatment to150-200 ppm nitrogen is expected to be beneficial.

Time to flower and growth habit following the cold treatmentvaried both within and among cultivars. General trends were, however, similar,and flowers appeared faster after a longer cold period (see Figure 1, right).Increasing the cold from 3-6 weeks reduced time to flower by approximately twoweeks. Another three weeks of chilling reduced flowering time by seven moredays, and 12 weeks of chilling, yet another seven days. On average, 21 dayswere required at 60° F for the first flowers to appear after 12 weeks ofcold, and 49 days with three weeks of cold. These results suggest plants can bekept at cold temperatures for long periods and forced for special occasions andmarkets. Plants grown at 60° F without any chilling did not flower withinthe seven months of the study.

Light during cold treatment

Recent studies with herbaceous perennials suggest a coldtreatment at higher irradiance will more efficiently induce flowers in somespecies than the recommended 100-150 fc. Plants were grown at 42° F and 100fc (one mol day-1m-2) or 900 fc (10 mol day-1m-2) during a 16-hour day. As acomparison, plants were also grown at 60° F and 100 or 900 fc. After sixweeks, all plants were grown at 60° F and 900 fc until flowering.Snowsylva, Rosylva and Bluesylva were included in this experiment.

Increasing the irradiance during the 42° F phase from100 to 900 fc did not result in faster or more efficient flowering. Earliestflowering at 60° F was observed for Snowsylva after 15 days following thesix weeks at 42° F and 100 fc. Bluesylva and Rosylva required 3-4 more daysto first open flower. For plants exposed to the higher irradiance during coldtreatment, flowering was delayed 8-10 days in all three cultivars. With theexception of limited sporadic flowering, plants kept at 60° F and 100 or900 fc did not flower.

The number of shoots and flowers was higher at 100 fc ratherthan 900 fc during the cold treatment. Bluesylva and Snowsylva producedapproximately 30 and Rosylva 20 flowering branches per plant using the 100 fcand 42° F environment. In contrast, the branch number decreased to 18 forBluesylva and 12 for Snowsylva and Rosylva when 42° F was combined with 900fc. The flower cymes and stems, however, were sturdier, and the plants morecompact with higher irradiance during the low temperature exposure. Keepingquality and duration of flowering may, therefore, vary depending on conditionsduring the cold treatment.

Plant management

Pinching the top growing point to release apical dominanceinduces branching and more flowering shoots. Since the effect of pinchingvaries from one plant species to another, experiments are required to determineproper timing, procedure and scheduling. Forget-me-not Compindi and Musik werepinched either immediately prior to or at the end of the 6-week exposure to42° F. Time to flower and number of flowering shoots were recorded at longdays and 60° F following the cold treatment.

The number of branches per plant increased to between eightand 12 with either a pinch prior to or at the end of the cold treatment.Without a pinch, plants produced, on average, 3-4 flowering branches. Pinchingplants at the beginning or end of the 42° F exposure generally resulted infaster flowering compared to intact plants. The faster flowering wasunexpected, as pinching is known to slow overall rate of growth and floweringin most other plant species.

Conclusion

Initial studies on the opportunity to produce forget-me-notas a flowering potted plant are promising. For best plant development andflowering, day length, temperature and light condition following the coldtreatment still need to be evaluated. Consumer acceptance of locally producedflowering potted forget-me-not has been overwhelming. The demand for specialoccasions and the scarce availability suggest consumers are willing to pay apremium price for flowering potted forget-me-not.