Depending on the cultivar, hollyhocks (Alcea rosea) may either be annuals, perennials, or biennials in their growth cycle. These towering blossoms create a spire of blooms that draw in hummingbirds and butterflies and may be cultivated successfully in zones 2 through 9 according to the plant hardiness ratings provided by the United States Department of Agriculture. It is not suggested to grow full-size hollyhocks in pots since they may grow to heights of six feet or more and generate enormous roots. However, dwarf kinds of hollyhocks often do well when grown in containers.
Hollyhocks need a very big container, like an old whiskey barrel, so that their roots have plenty of area to spread out and thrive. Despite the fact that dwarf kinds have more manageable root systems, the more space you offer them, the more content they will be. Choose a planter that has a depth of at least 12 to 16 inches and a diameter of at least 24 inches if you are going to be making it out of recycled materials.
Lighting and Positioning
According to the Cornell University Extension, hollyhocks grow best in full sun rather than in partial shade. The lack of light will prevent the plant from growing and flowering. These lovely blooms serve as a natural background for other, shorter flowers, and they direct the viewer’s attention upward. If you want your garden to seem larger and to have more height, you may want to think about positioning your container so that it is behind your flower arrangements.
Hollyhock roots need to be able to penetrate the soil in order to get water and nutrients. Soil that is lightweight and resistant to compaction is ideal. According to the University of Illinois, a soil that is good for growing hollyhocks in pots should be made from a combination of one part peat moss, one part perlite, and one part garden loam. This combination is porous enough to enable enough of air to reach the roots of the plant while yet enabling some moisture to be retained.
Water and Fertilizer
Because water drains out of the bottom of the container every time it is watered, plants that are grown in containers need to have their soil replaced more often than plants that are grown in soil. Each time you water, some of the nutrients in the soil will seep through the bottom of the pot. Because of this, giving your hollyhocks the nutrients they require on a 7- to 14-day cycle through the use of a water-soluble fertiliser formulated specifically for flowering plants, such as 15-30-15, mixed at a rate of 1 tablespoon of formula per gallon of water, will ensure that they are able to flourish.
When the earth is dry to the touch one inch below the surface of the soil, water the plant. It’s possible that you’ll need to water your hollyhocks every day if the weather is really hot and dry. Always water the plant until the water can be easily drained via the drainage holes on the bottom of the pot. This will ensure that the roots get the proper amount of moisture.
Hollyhocks have a continuous blooming period that lasts for a few weeks throughout the middle of summer and may continue to bloom into the autumn. You may coerce the plant into generating fresh blooms by removing the spent flowers from the stalk; nevertheless, the plant will ultimately cease producing flowers altogether despite your efforts. If you cut the stalk back to the rosette of leaves at the soil level, you can get a second round of flowers from the plant.