Alcea Rosea Annua

The Alcea rosea annua Spring Celebrities series from American Takii is a multi-use plant that can be grown as a cut flower, used in large containers or planted in the landscape. The mature height is about 36 inches, much shorter than the typical 4½-5 feet of older varieties, making the plants a more versatile size. Bred by Sahin, this long-blooming hollyhock produces dwarf, multi-stemmed plants with 2½- to 3-inch, semi-double to double flowers. Colors include Carmine-Rose, Lemon, Purple, White and a formula mix. Three new colors are being introduced this year: Crimson, Lilac and Pink.
 
Considered a first-year blooming biennial or short-lived perennial, plants are hardy to USDA Hardiness Zone 6 (possibly Zone 5). Plants are quite cold tolerant, though flowers will be damaged by frost. In the garden plants take full sun, are drought tolerant and attract butterflies. Seed should be sown from March through June in large plug cells (200 cell tray or larger) filled with a well-drained growing medium with a pH of 5.8-6.0. Cover the seed with vermiculite. Maintain 55°F-60°F for optimal germination. Keep the growing medium evenly moist through germination. Don’t allow the medium to dry out.
 
Germination occurs in eight to 10 days. Once germination occurs maintain a day temperature of 65°F-70°F and a night temperature of 55°F-60°F. Supply plugs with 75 parts per million nitrogen flushing the growing medium with clear water occasionally to prevent salts build up.
 
Plugs should be ready to transplant into finished containers in five weeks. Plugs should be planted before tap roots form. Plant one plug into a 1-gallon container filled with a well-draining growing medium with a pH of 5.8-6.0. Keep the medium pH level below 6.2 to avoid having the leaves turn yellow. Grow the plants at an average temperature of 55°F-60°F until they are well rooted and new growth starts. Drop the temperature to 53°F-55°F for finishing. Maintain a moderate moisture level and do not allow the medium to dry out. Excessive drying can result in the yellowing and loss of lower leaves.
 
Alceas are heavy feeders. Apply calcium and potassium nitrate at 75-100 ppm constant feed. Low fertilizer levels can result in the yellowing of lower leaves. Avoid ammonium nitrate fertilizer as this produces large cabbage-like leaves.
Plants can be pinched at the fifth to seventh node to produce multiple strong flowered stems for large pots. Pinched plants finish in 119-133 days. Non-pinched plants finish in 105-119 days during May to October. Because of the plant size that develops, one pinched plant is sufficient to fill an 8-inch or 2-gallon pot.
 
The plant growth regulators daminozide (i.e., B-Nine) and paclobutrazol (i.e., Bonzi) are effective at controlling alcea plant height. Check with the product manufacturers for recommended rates for trialing.
 
The most common insect pests are aphids, thrips and whitefly. Rust can be controlled with preventive sprays and providing adequate ventilation. 
 
For more: American Takii Inc., (831) 443-4901; www.takii.com.