Observation of Display Time and Research on Prolonging Flowering Time of Common Perennials in Beijing

In order to master display time of perennials more accurately and use perennials better,the three-year observation of 35 common perennials was made.The article changed traditional basic unit from month to ten days of flowering period,observed and recorded the view of perennials before flowering,flowering and after flowering for guiding practice.In order to prolong the view of perennials,13 perennials flowering period was purposed to prolong,the result showed the 10 of the tested perennials could flower twice.