Cosmos are beloved annual flowers known for their ease of growth and charming blooms. Their bright yellow centers and surrounding petals resemble the flowers children often draw, which adds to their widespread appeal.
Today, the variety of cosmos available has greatly expanded. In addition to the classic single-flowered types, there are now cultivars with unique petal shapes, such as quilled and fluted varieties. The ‘Cupcakes’ strain features fused flowers that resemble porcelain teacups.
Jonathan Sheppard’s Expertise
Jonathan Sheppard, a holder of the Plant Heritage National Collection, has dedicated the past two years to cultivating numerous cultivars of Cosmos bipinnatus. His success in this endeavor highlights the importance of plant conservation and the role of dedicated growers in preserving plant diversity.
Jonathan was initially drawn to cosmos because of their ease of growth. “Cosmos are a great starting point for those new to growing from seed,” he says. “They offer vibrant color, attract insects, and provide cut flowers. Many cultivars also cross-pollinate, allowing you to collect seeds and grow them year after year.”
As a collection holder, Jonathan must manage cross-pollination carefully to maintain the purity of each cultivar. Most of his plants are kept in individual black bins to protect them from rabbits. Additionally, he works to identify and clarify the various names given to different cultivars by seed companies, a common issue with annuals.
Variety and Differences
The introduction of the first lemon yellow cosmos, ‘Xanthos,’ led to different marketing names by various suppliers. Jonathan notes that while ‘Xanthos,’ ‘Lemonade,’ and ‘Kiiro’ appear similar, they each have distinct characteristics in flower and plant size. “Understanding these differences is part of my role, and I can provide feedback to seed suppliers if their seeds are not as true to type as expected.”
Jonathan does not have a single favorite cultivar. “Each plant can be a star in the right moment,” he says. For example, ‘Xsenia’ looks stunning in the right light, and he finds ‘Pink Mosaic’ particularly striking for its unique appearance. He also notes the changing popularity of cultivars like ‘Apricotta,’ which remains eye-catching despite shifting trends.
New Cultivars and Timeless Classics
Recent years have seen a surge in new cosmos varieties, including the fluted ‘Sea Shells’ and sherbet-colored options. There are also double flowers and those with anemone centers, such as ‘Pink Popsocks’ and ‘Fizzy Pink.’
Despite the influx of new varieties, Jonathan still values older types like ‘Dazzler,’ which, though larger and more robust, may take longer to bloom.
Growing Tips from Jonathan Sheppard
Jonathan offers several tips for growing cosmos successfully:
1. Cosmos are half-hardy annuals and should be planted outside only after the last frost. Although seed packets recommend sowing from February, it is often better to wait until mid-March or April, especially if you do not have a greenhouse.
2. Start placing cosmos outside during the day from mid-April and pinch them out for bushier plants when they have three sets of true leaves.
3. While direct sowing is possible, Jonathan prefers sowing seeds in a well-prepared seedbed to avoid issues with slugs.
4. Cosmos thrive in poor soil and excessive nitrogen can lead to more foliage than flowers. They are drought-tolerant but benefit from occasional watering and feeding, especially if grown in containers.
5. Regular deadheading encourages continuous blooming. Stop when plants become unsightly.
6. Although staking is not usually necessary, a support ring might be helpful for more delicate varieties like ‘Rubenza.’