Here Comes the Sun! - Sunflowers - (genus Helianthus)
By Gwen Kilchherr, Master Gardener
As July fades into August, the Sonoma garden often starts to fade, too. Too much heat literally bleaches out many of early summer's colors, and by late summer our gardens have lost their vigor. Want to give your garden an August-September shot in the arm? Plant sunflowers!
Most gardeners are familiar with the annual sunflower, with the dinner-plate sized flower on a single stalk. While those are great fun to grow, most of us don't have the room for them. In fact, the vast majority of the sunflower genus are annuals. However, it is the perennial varieties that coexist most happily with other garden plants, and once planted, require little more than an annual cutting to the ground when they go dormant in winter, but bounce back to life and burst into dramatic display every August.
As their name suggests, plant all varieties in full sun, although some late afternoon shade is fine if you are in one of the hotter parts of the County. In exposed, windy sites the taller kind with large flowers must be staked or they'll end up at 45° to the ground. Also beware of snails and slugs when they are still young plants. Other than that, they are delightfully uncomplaining and easy to grow.
Some great perennial varieties are:
Helianthus angustifolius- Swamp Sunflower: 6 ft tall with a much branched stem and rough, sandpapery leaves 3-6 inches long but only a half inch wide. The happy yellow flowers, 2-3 in across, are borne profusely in late summer and autumn.
Helianthus gracilientus "Slender Sunflower": A long bloomer - quite refined with its slender, branching stems, it will bear hundreds of cheery, 2", bright yellow daisies May to October.
Helianthus laetiflorus "Showy Sunflower": growing 4' to 8' tall & bearing lots of yellow blooms on long stems very late in the year - August thru Fall.
Helianthus maximilianii "Prairie Sunflower": From the Midwest comes this beautiful, tall (6-8') Sunflower that bears huge numbers of 4" golden yellow flowers clustered in eye-catching spires
Helianthus mollis - "Downy Sunflower": bears lovely, soft, grayish green foliage covered with fine hairs. Lemony yellow, 3"- 4" flowers are borne July thru October & are highly attractive to butterflies.
Helianthus salicifolius - "Willow leaf Sunflower": 4' to 8' tall but is not fussy about soil at all. The unusual, willow-like leaves surround the vertical stems, helping to make it a stunning vertical accent. The 2" - 2.5" bright golden blooms have dark centers & sway beautifully atop the stalks.
Annual sunflowers: These plants must be seeded (or started from small plants) annually. There is a much wider variety of color and bloom size amongst 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, plant the seeds close - 8 inches apart - and avoid using nitrogen-rich fertilizers that promote leaf production at the expense of flowers. Good draining soil with added compost is best, because the aim is to encourage more flowers than leaves.
A few popular tall growing annual varieties are:
* H. 'Moonwalker': grown for its yellow face with a chocolate dark centre; best at the back of a border where it reaches a height of 4ft to 5ft.
* H. 'Pastiche': available in mixed shades of reds, yellows and buffs which nicely blend together. The flowers appear on multi-stemmed plants that make a very effective screen - from 1.2m to 4ft to 5ft high.
* H. 'Russian Giant': the one to get if you want to be in the record books. Capable of hitting 10ft high with a huge face of yellow petals surrounding the dark centre. Spectacular!
* H. 'Velvet Queen': sumptuous velvet-red petals surround chocolate centres on tall, free-flowering growth to 5ft high.
*H. annuus 'Delta Sunflower': This is a wonderfully big and prolific wild sunflower from California that grows out by the delta, near the San Francisco Bay. It grows to 6' tall and 4-5' wide and blooms like crazy for months. Makes a great show in the garden.
There are several smaller plants that flower at or below the height of a child. Grow in containers or at the front of a border.
* H. 'Big Smile': an aptly named midget that won't grow above 1ft high.
* H. 'Teddy Bear': produces downy, double blooms without a central zone on short stems.
Good value; 2ft high.
Pollen-free hybrids, mostly from Japan and Europe, have been bred for flower arrangers who want to avoid pollen stains. They usually have shorter stems than the ones with pollen, and are much easier to use in floral arrangements.
* H. 'Music Box': its flowers range from creamy yellow to an unusual dark reddish-brown; 28in high. Other good choices include 'Big Smile', 'Full Sun', 'Sonja' and 'Sunspot'.
Pick flowers early in the day, but wait until the sun has dried the dew. Remove leaves that are low on the stem, leaving just two or three higher up, near the flower's face. Place the flowers in a bucket filled with water, and leave them to 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 when kept in water.
Perennial Helianthus are available at California Flora Nursery in Fulton, and seeds for annuals from most nurseries, hardware stores and specialty seed vendors.
Good companion plants for Helianthus in the late summer garden are: tall ornamental grasses such as Miscanthus or Calamagrostis, Salvias, Solidagao, Asters and Agastache.