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Cineraria

Series: Venezia™, Jester®

 

1. Soil and pH Needs

Cineraria plants need a constantly moist but well-draining soil to prevent wilting and premature loss of flowers. Heavy clay soils will retard root growth and starve the plant of oxygen, which can lead to root diseases. Soil should be amended with fully composted organic matter prior to planting and in the case of clay soils the addition of Canadian sphagnum peat moss and well-rotted compost are good sources of organic matter that will aid in aeration. If possible, incorporate two to three inches of organic matter into the top six inches of soil. If adding organic matter, be aware that organic matter that has not been fully composted will tie up nitrogen and sulfur leading to nutrient deficiencies and poor growth.  Soil pH should be between 5.9- 6.2 for optimum growth; and should be tested prior to planting but after adding any amendments. This can be done quite easily with a portable pH tester available for about $100. Mix one part soil with two parts distilled water, stir well and wait thirty minutes, then follow the instructions for using the pH meter. If pH is too low, the addition of lime is warranted. However, the rate will vary depending on how much you need to raise the pH and the type of soil you are dealing with. Clay soils or those with a lot of organic material have a high buffer capacity and require more lime than sandy soils, which have a low buffering capacity. A good soil testing lab can determine the lime requirement index (LRI) of your particular soil and can recommend types and rates of lime to use. The frequency of watering will depend on the type of soil, weather conditions and the amount of mulch. Mulch will not only reduce soil water evaporation but will also reduce splashing of water onto the lower leaves, moderate soil temperatures and reduce weed competition. Water in the morning into the soil around the plant, never into the crowns or leaves. Cinerarias are thirsty, so the soil should be kept moist with regular deep watering.

 

2. Fertility

Cinerarias are light to moderate feeders once in the landscape.  An application of a balanced controlled-release fertilizer (CRF) such as 10-10-10 or 14-14-14 with a 3-4 month formulation applied to the bed at planting will keep the plants well fed, depending on the amount of irrigation applied and the average daily temperature. In high pH soils (alkaline soils) additional iron or iron sulfate may be beneficial to reduce chlorosis (yellowing) of the foliage.  Yellow foliage on Cineraria may also be caused by a nitrogen deficiency within the plant. Both can be corrected with the proper supplemental fertilizers. 

 

3. Disease

The primary diseases to be aware of are powdery mildew, Alternaria leaf spot and downy mildew. A plant with powdery mildew will have white fungal growth on the upper leaf surface; it may also form on the flower petals. Alternaria leaf spot will begin as dark brown to black leaf spots. These will enlarge to engulf large portions of the leaf. Spots may also form on the petioles that can cause them to break. Downy mildew will start as yellow spots on the leaves that later turn black. Sparse fungal growth may appear on the underside of the infected foliage. Cineraria are also susceptible to Impatiens Necrotic Spot Virus (INSV). Symptoms of an infected plant include the leaves being mottled with yellow spotting, dead flecks or line/ring patterns. Plants may also be distorted, show flower color breaking or may be stunted. Infected plants should be immediately destroyed since there is no cure. Implementing a good thrips control program will kept INSV in check since the virus is vectored through by thrips. These diseases can be avoided by employing proper cultural practices such as: avoiding overhead irrigation, improper plant spacing, poor air circulation, and watering too late in the day.

 

 

Symptoms of powdery mildew on the top of the leaf

 

INSV symptoms on leaves and stems

 

4. Insects

Cineraria are susceptible to aphids, whiteflies, thrips and leaf miner. Aphid nymphs and adults feed on the plant sap by piercing the tissue. This slows growth and can cause leaf curling. Aphids also excrete honeydew. The honeydew will lead to sooty mold formation which will reduce growth and production. Thrips cause damage to the plant by piercing and sucking cells on the leaf surface. This causes silver-grey spots to form on the foliage. At high infection rates, the leaves may wither. Thrips are also a primary vector for virus transmission. Both adult whiteflies and larvae extract food from the plant. This affects the plant’s processes and results in reduced growth. Leaf miner damage is caused by the larvae mining below the leaf surface after the female has laid her eggs. The leaf tissue dries and turns brown. Remember that healthy, vigorous plants are less susceptible to pest damage than unhealthy plants.  

 

Aphid infestation along the stem

 

Adult Western Flower Thrips

 

Whitefly population on the leaf underside

 

 

Signs of leaf miner damage

 

5. Tips for Success

  • Cinerarias grow best in moist, slightly acidic soil with light shade.
  • When irrigation is necessary, water thoroughly and never into the crown of the plant.
  • Deadheading (removal of spent flowers) will prolong bloom time and help produce a fuller plant.
  • Remove weeds from the plantings that compete with Cineraria for moisture, nutrients and light.