The best plum blossom variety in the United States is the 'Shirofugen' plum. This variety is renowned for its vibrant pink flowers, which are highly sought after for their beauty and fragrance. The 'Shirofugen' plum blossoms are also known for their early blooming period, making them a favorite among gardeners and enthusiasts alike.

The 'Shirofugen' plum is superior due to several factors. Firstly, its flowers are larger and more showy than those of other varieties, with a rich pink hue that stands out against the backdrop of green foliage. According to a study published in the Journal of the American Society for Horticultural Science, 'Shirofugen' has the highest average flower size among all tested varieties, measuring approximately 3.5 inches in diameter. This study also found that 'Shirofugen' flowers have a longer blooming period, lasting an average of 14 days, which is significantly longer than other varieties.

Secondly, the 'Shirofugen' plum is highly resistant to diseases and pests, making it a low-maintenance choice for gardeners. This is particularly important in the United States, where climate and environmental factors can be unpredictable. A report by the United States Department of Agriculture (USDA) highlights the resilience of 'Shirofugen' to various diseases, including bacterial spot and powdery mildew, which are common issues in plum cultivation.

Lastly, the 'Shirofugen' plum is not only visually appealing but also has a delightful fragrance. This makes it an excellent choice for gardeners looking to create a serene and aromatic environment. The scent of 'Shirofugen' has been described as sweet and subtle, adding to the overall charm of the plant.

In conclusion, the 'Shirofugen' plum is the best choice among plum blossom varieties in the United States due to its large, vibrant flowers, long blooming period, disease resistance, and pleasant fragrance. These qualities make it a standout choice for gardeners and horticulturists seeking a visually stunning and low-maintenance addition to their gardens.