Helianthus — Sunflowers
As July fades into August, gardens often start to fade, too. Excess heat bleaches out many of early summer's colors, and as the weeks progress many plants lose their vigor. For a late-summer shot in the arm, sunflowers may be the answer.
Sunflowers in the genus Helianthus are incredibly easy to grow in summer borders and children's gardens. They can reach more than head height with big or small flower heads in a wide range of colors, but some make shorter, bushier plants with even more colorful heads. They can be grown in forest-like clumps, in rows to make summer screens, or as surprise features shooting high above much smaller plants among garden beds. All types are valued for their cut flowers and for attracting bees and birds that devour the large seeds.
Most gardeners are familiar with the tall, dinner-plate sized annual sunflowers on a single stalk. While those are great fun to grow, most gardens don't have room for them. In fact, the vast majority of the sunflowers are annuals. However, it is the perennial varieties that coexist most happily with other garden selections, and once planted, require little more than an annual cutting to the ground when they go dormant in winter. In spring they bounce back to life then burst into dramatic display every August.
As their name suggests, all varieties are best planted in full sun, although some late afternoon shade is helpful in hotter parts of Sonoma County. In exposed, windy sites, unless taller types with large flowers are staked, they will bend or be blown over. Snails and slugs can be picked off young plants if they become bothersome. Other than that, sunflowers are delightfully uncomplaining and easy to grow.
Some popular perennial varieties are:
Helianthus angustifolius, swamp sunflower, grows to 6 ft. tall with a much branched stem and rough, sandpapery leaves 3-6 in. long but only ½ in. wide. The happy yellow flowers, 2-3 in. across, are borne profusely in late summer and autumn. Moderate water is needed.
Helianthus gracilentus, slender sunflower, is a long blooming California native that is quite refined with slender, branching hairy stems to 6 ft. tall and nearly as wide. It bears hundreds of cheery 2 in. bright yellow daisies May to October. Once established it is completely drought tolerant and deer resistant.
Helianthus laetiflorus, showy sunflower, grows 4-8 ft. tall filled with yellow blooms on long stems very late in the season from August thru fall. Drought tolerant once established, this perennial travels annually by underground stems and is best planted where it has room to spread.
Helianthus maximilianii, prairie sunflower originated in the Midwest. It is another 6-10 ft. showstopper that bears huge numbers of 3-4 in. golden yellow flowers. It tolerates nearly any soil type, requires little water, and also spreads by rhizomes to form colonies that require ample space.
Helianthus salicifolius, willow leaf sunflower, grows 5-6 ft. tall and 3 ft. wide that produces clusters of 2-2½ in. bright golden blooms with dark centers. The unusual long, drooping, willow-like leaves surround vertical stems, helping to make it a stunning vertical accent that sways beautifully atop the stalks. It is not fussy about soil as it spreads to form dense colonies.
Annual sunflowers must be seeded (or started from small transplants) annually. There is a much wider variety of color and bloom size among the annual varieties, but they do not lend themselves to integration with the rest of the garden nearly as well as the perennials and are generally grown for flower cutting.
Growing sunflowers for cut blooms is best done in a section of garden put aside especially for this use. You can then take as many as you wish without spoiling the display. Because high yields take priority over beauty, place plants close together and avoid using nitrogen-rich fertilizers that promote leaf production at the expense of flowers. Fast-draining soil with added compost is best.
A few popular, tall growing annual cultivars of Helianthus annuus include:
'Delta Sunflower,’ a wonderfully big and prolific native that grows in the San Francisco Bay delta, 6 ft. tall and 4-5 ft. wide and blooms for months in a great show in the garden.
'Velvet Queen,' with sumptuous velvet-red petals surrounding chocolate centers on tall, free-flowering growth to 5 ft. high.
'Pastiche,' blooming in mixed shades of reds, yellows and buffs that blend nicely together on multi-stemmed plants that make a very effective screen from 4-5 ft. high.
'Moonwalker,' grown for its yellow face with a chocolate dark centre, best at the back of a border where it reaches a height of 4-5 ft.
'Russian Giant,' a spectacular cultivar 10 ft. high with a single huge face of yellow petals surrounding the dark center.
Smaller sunflowers for the front of a border or in containers are 'Big Smile,' an aptly named midget that won't grow above 1ft. high; and 2-ft. tall 'Teddy Bear,' that produces downy, double blooms on short stems.
Pick sunflowers early in the day after dew has dried. Remove leaves low on the stem, leaving just two or three higher up near the flower's face. Place stems in a bucket filled with water, and leave them stand for several hours in a cool room before placing in a vase. Change the water every few days. Blooms can last up to two weeks.