How to Grow and Care for Hollyhock (Alcea)

Hollyhocks, also known as Alcea, have over 60 species of tall, pretty flowers that are available in almost every color (including black). These perennial or biennial flowering plants grow to 8 feet tall. Their height and large blooms make them ideal candidates for adding to the back of borders or growing up against walls or fences. Hollyhocks prefer full sun and temperate climates but don't do well in high humidity.

Hollyhock Care

Although there is variation in care requirements across hollyhock species, most are known for being adaptable and relatively cold-hardy plants that can be grown in many regions in the United States.

• Plant hollyhocks in full sun for best flowering.
• Choose a garden spot for your hollyhocks that has good drainage.
• Shelter hollyhocks from the wind to prevent the tall stems from flopping.
• Space individual hollyhock plants between 18 and 24 inches apart to promote good air circulation to avoid rust fungal disease.

Light

Plant hollyhocks in full sun, but they can survive in partial shade. These tall plants can flop in overly shady locations. If you live in a particularly hot and dry region, a partial shade location will prevent the lower leaves on your hollyhock from withering.

Soil

Grow versatile hollyhocks in any soil type. Rich, well-drained soils can produce the best results, but amending with organic matter is often all that is needed to boost your plants in poor quality, infertile conditions. This will also promote better air circulation and drainage.

Water

Water seedlings and young hollyhocks consistently to keep them moist. Aim to keep the top 5 inches of soil damp. Once established, your hollyhocks may only need watering when you experience prolonged hot and dry spells.

Water hollyhocks at the roots and not on their leaves to help prevent problems with the fungal disease rust.

Temperature and Humidity

Hollyhocks grow best in temperate regions. They are reasonably cold-hardy, and some species can survive in temperatures as low as 0°F, but early fall frosts can damage late blooms. These plants don't like high humidity because of their susceptibility to rust.

Fertilizer

Feed hollyhocks because they are fans of fertile conditions and do best with high levels of nutrients in the soil, or their foliage will yellow, and blooms will diminish. If your soil isn't rich, amending with organic matter during the spring is beneficial. Fertilizing isn't necessary in fertile soils, but in poor soils, feeding every two to four weeks during the bloom period can also help. An organic flower fertilizer or a fish emulsion that is high in nitrogen works well.

Types of Hollyhock

The common hollyhock (Alcea rosea) is the most well-known and cultivated species of hollyhock, though others would look just as at home in a traditional cottage garden setting. Some cultivars of this species are more rust-resistant, taller, or cold-hardy than others. Here are popular hollyhock cultivars:

• Bristly hollyhock (Alcea setosa): Flowering earlier than the common hollyhock, this species typically blooms from April to June, grows in USDA Hardiness Zones 5 to 9, and the blooms are pink.
• Russian hollyhock (Alcea rugosa): Not as cold-hardy as the common hollyhock, this yellow single-flower species is resistant to hollyhock rust.
• 'Chater's Double' (Alcea rosea):A common hollyhock cultivar, this beautiful double-flowered variety comes in many shades and blooms right through the summer.
• 'Blacknight' (Alcea rosea):A striking single to semi-double flower, this is an almost black hollyhock. This cultivar is a true perennial rather than a biennial variety.

Pruning

Cut back the plants after their bloom period in the fall and remove any plant debris or infected plants to help prevent the spread of unwanted growth and disease. Water carefully, space plants appropriately, and continue to remove the leaves on the lower part of the stem to minimize any problems.

Deadheading your hollyhocks prevents them from growing in unwanted areas of your garden (unless you want new growth, then skip this step). As for the flowers, these can be removed after the colors fade. Simply cut the flower off at the base of the bud or pinch the bud with your fingers.

How to Grow Hollyhocks From Seed

Hollyhocks readily self-seed, and new plants will likely pop up the following year without any effort on your part. To introduce new plants into the garden, most gardeners stick with growing hollyhocks from seed. Follow these general tips for a more successful germination rate, but always check temperature and timing specifics for each species or cultivar:

• Sow seeds indoors during the second half of spring or in early summer outdoors.
• Ideal temperatures for germination are usually around 60°F to 70°F.
• If you sow seeds in the fall, you can overwinter them in a cold frame or greenhouse, and they should flower the following year.
• Hollyhocks typically take around two weeks to germinate.
• At the end of the blooming season, gather the seeds from wilted flowers and dry them in the sun. Once fully dried, place them in an envelope until you are ready to plant.

Common Pests & Plant Diseases

The main problem for hollyhock species is the fast-spreading fungal disease rust (known as Puccinia malvacearum). This affects the plant's foliage and can cause leaf drop and damage, discoloration, and stunted growth. You will notice yellow or orange spots on the leaf's surface. Once this happens, it is very difficult to control and remedy, even with fungicide, so it may be best to remove the sick plant entirely before it affects others in the garden.

Slugs are interested in munching on hollyhocks' young foliage, and Japanese beetles and spider mites also find these species attractive.

How to Get Hollyhocks to Bloom

Bloom Months

Known for their long-lasting bloom period, hollyhocks typically flower in early summer through the fall, between June and September. Flowers begin to blossom from the bottom of the stem and open gradually upward. They easily self-seed, so you will have beautiful, long-lasting blooms every summer.

What Do Hollyhock Flowers Look and Smell Like?

Hollyhock flowers come in many bright colors, including white, pink, red, yellow, and lavender. The size and appearance of your hollyhock flowers will depend on the species you select. They are typically large (often around 5 inches in diameter), outward-facing, and on a long central stem. They do not emit a scent.

How to Encourage More Blooms

To make the most of the bloom period and to encourage large, healthy flowers, make sure your hollyhocks get enough nutrients, consistent moisture, and deadhead spent flowers.

Common Problems with Hollyhock

Hollyhocks are easy-care and most are known for being adaptable and relatively cold-hardy. But you may encounter a few problems that can be easily resolved.

Leaves Wilt or Droop

Wilting, drooping hollyhock leaves may indicate that the plant needs more or less water.

Leaves Turning Yellow

If your hollyhock's leaves are turning yellow at the tips, the plant is receiving too much water.

Leaves Curling

Curling hollyhock leaves may mean the plant is experiencing heat stress from harsh sunlight. Either reposition the plants in a shadier area or put up a shade-cloth barrier for relief. Add mulch to the soil to keep the plant's roots cooler.

Overall Sickly Appearance

If your hollyhocks look stunted and weak, they likely have the Puccinia malvacearum rust disease. It starts with yellow or orange spots on the leaves that turn into lumps, and the foliage shrivels and drops. Immediately remove infected plants and dispose of them in a closed bag.

From: thespruce