Summer is not usually a big season for blooming Petrocosmeas, with most species being autumn and winter bloomers. An advantage to having a larger and more diverse collection of Petrocosmea hybrids and species is that there are some which do flower in the summer. For me, P. barbata, P. nervosa and P. parryorum have become reliable summer bloomers. Hybrids incorporating these species also show a tendency to flower during the longer and warmer days of summer.
A few years ago, I was excited to add two new cultivars selected from a remake of the same cross that produced the old hybrid P. 'Momo'. This time, Mr. Nakayama, who incidentally produced 'Momo', chose two cultivars that exhibited new and desirable qualities. P. 'Asa Blue' was selected for it's tendency to produce tremendous quantities of large blue flowers. Now, after growing this hybrid for several years, I can say that it clearly takes a few years for it to reach it's prime. My original plant, pictured below, has finally shown it's potential for me. The plant shown is currently putting on a spectacular show on the north facing window sill of my bedroom. What a joy it has been to awaken to this joyous sight each morning for the past two weeks. It shows no sign of fading and there are still lots of buds coming along. Today, I counted 56 open flowers. The plant has been growing in a five inch pan pot for the past four years, and has not been repotted. I have grown it under lights, until two weeks ago, when I brought it to the windowsill so that I could enjoy the show more readily. I advocate keeping Pets in the same pot for several years, and not over feeding. I also believe that allowing the plants to get dry between waterings encourages more flowers. Overfeeding and keeping plants constantly moist, at least for me, produces large leafy plants, but few flowers.
P. 'Asa Blue' (above) in flower this morning on my north facing bedroom windowsill.
P.' Asa Blue' also has been successful as a parent in one cross for me. The photo below shows one of it's progeny...P. 'Keystone's Brilliant' (P. 'Asa Blue' x begoniifolia). This cultivar was selected for the bicolored flowers with lots of white in the throat. A nice yellow center also adds to the brilliance of these flowers. My one plant of this hybrid is just now coming into flower. It has always flowered in summer for me, making it another hybrid with potential as an "off season" bloomer among this genus which mostly flowers in the winter.
P. 'Keystone's Brilliant' just coming into flower.
As more and more hybrids are produced, hopefully, we will one day have Petrocosmeas in flower all year long. For now, these few summer-blooming Pets are treasures in the long, hot days of summer.