A standout garden staple spanning countless generations of gardeners, Alcea rosea (al-SEE-ah RO-see-ah), or hollyhock, formerly Althaea, is an iconic landscape standout with a commanding presence in the landscape. Belonging to the mallow family, Malvaceae, hollyhock have been cultivated since at least the 15th century, with their true nativity unknown, believed to have been first imported to Europe from China, and ultimately seen as a cultigen—a plant species or variety known only in cultivation, especially one with no known wild ancestor—though likely originating from Turkey.
A true biennial, hollyhock historically lives for about two years in the garden. In the first season, plants generally do not flower, existing only as a low rosette of large, wrinkled, three- to seven-lobed, rounded leaves up to eight inches across, storing nutrients and resources in preparation for an incredible blooming display in their second season. After flowering, plants usually die, however hollyhock readily reseed, remaining in the garden as colonies build over time, eventually almost appearing perennial as bloom times stagger between groupings of first- and second-year plants.
Biennial hollyhock seeds sown the previous fall will also bloom in their first season of growth the following summer, acting more as an annual or tender perennial than a biennial. Additionally, modern strides in plant breeding have developed some truly perennial cultivars of hollyhock, notably the Spotlight™ series, which reliably bloom year after year, performing well even in their first season of growth. Non-blooming plants may also be divided in the spring or fall, though care should be taken to avoid disturbing their deep taproot, as plants generally do not respond well to transplanting or disturbance of their deep roots.
Blooming throughout the summer, hollyhocks send out rigid flower stalks reaching unbelievable heights upwards of six to eight feet tall without any support needed, though gardeners should take care if particularly high winds are expected or if hollyhocks are planted in open areas prone to sustained winds. These towering spires are decorated with massive, outward-facing, bowl-shaped single, semidouble, or double flowers up to five inches in diameter in a variety of bright colors and even bicolored varieties. The array of Alcea cultivars available spans a wide range of heights and colors, such as the semidouble flowers of the ‘Queeny’ series, including the compact habit and bright purple-pink blooms of ‘Queeny Purple,’ perennial bright red single blooms of Spotlight™ ‘Mars Magic,’ perennial yellow blooms of Spotlight™ ‘Sunshine,’ and the dramatic deep purple blooms of the nearly black perennial Spotlight™ ‘Blacknight.’
Though resistant to deer and rabbit feeding and tolerant of juglone produced near black walnut trees, hollyhock foliage is prone to disease including leaf spot and mallow or hollyhock rust (Puccinia malvacearum), though simple precautions can help considerably in preventing disease outbreaks. Leave adequate spacing of at least 18” between plants to encourage consistent airflow around foliage and avoid watering on the leaves or placing plants where they may be regularly moistened by sprinkler systems. Affected plants can be removed to prevent disease spread, or targeted, preventative applications of mild fungicide can be used in areas of concern before disease appears or immediately when the first signs of infection appear.
Alcea thrive in a range of soil conditions, preferring evenly moist, fertile soils in full sun, and are intolerant of excessively wet or poorly drained sites as they are prone to root rot, especially if plants are kept consistently wet while dormant. Hollyhocks are superb for adding needed structure and height in the back of sunny borders, massed as a showy specimen or background planting, incorporated into cottage garden designs, or used to cover open walls or fences. Be sure to fertilize every few weeks with a bloom focused fertilizer to keep these heavy feeders happy and blooming their best.