Hollyhock Size: How Tall Do They Get?

Hollyhocks are known for their towering stalks and beautiful flowers and known for being grown in cottage gardens or farmsteads. These beautiful plants are gaining popularity again due to their winter hardiness and versatility. 

Before you decide to plant, you must understand how tall these plants can get. Choosing the right location is important because they can easily overpower other low-growing plants. Other factors go into how tall your hollyhocks can get, such as sunlight, water, and soil conditions. 

By lining hollyhocks along a fence or building, you will add dramatic height to your garden spaces. Keep reading to discover how large hollyhocks can get and some popular varieties to add to your space. 

The Long Answer

Hollyhocks are biennials that only have a two-year life cycle. The first year is spent growing roots and storing nutrients for the following year. In the second year, hollyhock will shoot up and produce beautiful towers of flowers.  

Hollyhock height will look different depending on the life cycle of the plant. In the first year, the plant will be very low and shrub-like. They produce a cluster of large, velvety leaves that don’t produce flowers. 

In the second year, your hollyhocks will change dramatically from the first year. The plant will begin to grow stalks that can reach amazing heights, and stakes of flowers will begin to bloom. Classic varieties have a mature height of about 5 to 8 feet tall. They can grow taller if conditions are ideal. 

Different Species and Their Sizes 

Hollyhock has been around for centuries and is known for soaring above cottage gardens. The classic varieties are the tried and true hollyhocks. These are the most common hollyhock and are the tallest of all varieties. 

With over 80 species of hollyhock, there are endless options for height and flower color. Let’s consider some common species and how tall they can get. 

Common Hollyhock

The common hollyhock, Alcea rosea, is one of the tallest hollyhocks grown. The average height of this species is around 6 to 8 feet. This classic beauty will shine above all other plants. Under ideal conditions, it’s common for this variety to grow over 8 feet tall. 

Through the development of hybrid forms, they have made a few cultivars of Alcea rosea shorter. Some varieties are as short as 3-4 feet tall. Many of the hollyhocks we see today are bred using Alcea rosea as one of the parent plants but may be hybridized with other Alcea species. These varieties are a great choice for containers or walkways. 

This species blooms from June to August and reaches heights of 5 to 8 feet. The common hollyhock is available in a myriad of colors, from white to yellow and pink to red, many of which are excellent at attracting hummingbirds and butterflies. 

Fig-Leaved Hollyhock

Better known as the fig-leaved hollyhocks, Alcea ficifolia originally only had yellow flowers. Through hybridization with Alcea rosea, a dramatic range of colors of hybridized plants have emerged. This species has a mature height of 6 to 7 feet tall. 

Naturally rust-resistant, the fig-leaved hollyhock is a great option in hot and humid climates where rust or other fungal diseases are common. Plant in full sun, and this species will grow to amazing heights. 

Russian Hollyhock

This Russian species, Alcea rugosa, only produces beautiful lemon-colored flowers. This species typically has a mature height of 6 to 8 feet tall. Since this hollyhock is native to the colder weather of Russia, it is hardy enough to handle harsh winters in the United States. 

They generally flower from June through August. Their leaf shape is similar to Alcea ficifolia in that it’s reminiscent of the shape of fig leaves, but that’s their only true similarity. Hummingbirds love this species, and these can be an excellent addition to a pollinator flowerbed. 

Sunlight

The amount of sunlight your hollyhock receives will determine its eventual growth. Planting in full sun will produce the most flowers and the healthiest plants. If planting in zones above an 8, consider planting in a location that has full morning sun but afternoon shade to avoid stress from excessive heat. 

Hollyhock tolerates partial shade, but planting in full sun will increase flowering and foliage growth, resulting in taller plants. Be sure not to overcrowd your hollyhocks. Overcrowding can stunt growth and encourage disease formation. 

Soil Conditions

Hollyhocks are versatile but should be planted in rich, moist soil conditions and prefers a soil pH of 6 to 8. If your soils tend to be dry and lack nutrients, don’t panic. Your soil health can be improved by adding organic matter, like compost. 

Consider adding organic matter if your region has sandy soils. This soil type tends to leach nutrients and water. Adding organic matter can also be beneficial to loosen up hard-packed clay soil. There are many types of organic matter to choose from, and you most likely have some at home waiting to be composted! Grass clippings, dead leaves, and kitchen scraps are good examples. A good-quality straw mulch or wood chip mulch on the soil’s surface is another way to add organic matter, as these mulches will break down into the soil over time.

Water

Noted for being drought tolerant, they can tolerate a lack of water for quite a while. Although they don’t need much water once established, frequent watering is necessary when the plant is young, and as a mature plant, it can help improve the overall growth of your hollyhock. 

Consider watering a few times weekly to keep the hollyhock blooming all summer. Water until the soil is moist, about 3 to 4 inches below the soil surface. If your region is experiencing long periods of hot and dry conditions, consider watering more frequently. 

On the opposite end of dry, hollyhocks don’t like soggy soil conditions. Hollyhocks can develop root rot and other diseases if they are grown in extremely wet soil. In addition, due to their height, they can be knocked over by wind or animal passage if the soil is too wet to provide a solid footing for their root systems. Consider staking your hollyhock if you live in a windy region. 

Pruning

Prune hollyhock to help control the self-sowing of seeds and produce bigger stalks with increased flowering. Hollyhocks produce many seeds, so deadheading the flowers as they fade will help control their spread. Simply cut or pinch off the spent flowers before they produce seed. 

This will allow the plant to focus on stalk growth and flower production. Leave the finished blooms on the stalk towards the end of the season. These last flowers can then self-sow, resulting in flowers for the next year. 

Consider collecting the seeds and storing them until you are ready to plant in the spring. To do this, place a fine mesh bag over the flowers as they start to fade, tying it tightly to the stem to ensure seeds don’t escape the bag. Once fully dry, cut the finished flowers from the stalk. Shake the bag to knock the seeds from the spent, dry flowers, then store them in a cool, dark, and dry location. Paper envelopes work best for seed storage as they allow moisture to escape; plastic baggies can lock the moisture in with the seeds and cause them to rot.