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Growing Hollyhock Plants in a Pot

Althaea rosea / Hollyhock Flower
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Hollyhocks (​Alcea rosea​, USDA zones 2-10) are biennial flowering plants. Cornell University describes how these plants mimic the growth of a perennial plant because they are known for their ability to self-seed, which results in new plants each year. They are tall growing plants, usually reaching between 5 and 6 feet high. Hollyhocks produce brilliant, showy, 2- to 4-inch-wide flowers in a wide array of colors, including, rose, pink, white, yellow, violet and red.

Plants can be started from hollyhock seeds and easily grown in large ceramic pots or in wooden tubs or barrels. You can use a smaller container if you grow dwarf hollyhocks. Although standard-size hollyhocks may grow to 10 feet or taller, the University of California notes that the dwarf hollyhocks in the Queeny, Majorette and Celebrity series grow about 3 feet tall.

Germinating Hollyhock Seeds

Fill up a planting tray with a good quality, sterilized seed-starting mix. Plan on starting hollyhock seeds indoors about five to six weeks before the last spring frost date in your growing region. Firm the mix down in the planting pack using your fingers, a fork or a spoon.

Place one to two hollyhock seeds on the surface of the growing mix in the cells. Firmly press the seeds into the mix to a depth of approximately 1/4 inch. Mist the seeds with water to ensure good soil-to-seed contact.

Place the seed-starting tray in the brightest lit area in your home that is not going to provide direct sunshine. A south- or west-facing window is ideal and will keep the temperature warm enough the seeds should begin germinating in seven to 14 days. Keep the mix moist, but not soggy wet.

Transplant the hollyhock seedlings when each has two to three sets of leaves.

Growing Hollyhock Plants in a Pot

Choose a suitably sized planting pot. Keep in mind hollyhocks can grow to 6 feet tall, so choose a pot that is large enough to accommodate the hollyhock plants plus planting stakes. Select a heavy pot so the tall, mature plants do not cause the container to fall over in strong winds.

The best spot for where to plant hollyhocks is in a location that is going to provide the hollyhocks with maximum sunshine. Although the plants may grow in a shady spot, blooming will be compromised.

Place potting mix into a large basin or wheelbarrow until there is enough to fill the planting pot about 2/3 full. Mix into the potting mix approximately 1 cubic foot of dehydrated compost, aged manure, leaf mold or peat moss.

Scoop the potting mix and organic matter mixture into the pot to fill it to approximately 2 inches from the top of the rim.

Dig planting holes spaced about 8 to 10 inches apart that are the same depth and width of a cell in the planting pack.

Remove a hollyhock seedling from a cell in the planting pack. Place your thumb and index finger at the bottom of the cell and push upward gently.

Plant the seedling into one of the planting holes. Scoop potting mix in and around the seedling, firming it down as you proceed.

Mix into a gallon of water an appropriate amount of starter fertilizer such as 15-30-15, 16-32-16 or similar type. Follow the instructions on the label so you will know how much to use. Water each of the seedlings with approximately 1 quart of the fertilizer-and-water solution.

Tip

You can plant hollyhocks in planting pots at any time from May through September.

Push in a 3- to 4-foot-high planting stake near each hollyhock once they have grown at least 6 to 8 inches tall.

Plan on watering container-grown hollyhocks about two to three times a week, depending on conditions. Provide enough water to moisten the soil at a depth of 6 to 8 inches.

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