‘Clear Crystal Purple Shades’ and ‘Clear Crystal White’ are part of a new tetraploid alyssum series bred to deliver more vigor than standard diploid varieties. Few plant growth regulators are needed in most markets, and these cool-season crops can be grown with little or no heat.
Germination takes three to four days. Use a well-drained media with a pH of 5.5-6.0 and EC less than 0.75. Maintain a temperature of 70-72° F. Maintain 95 to 97 percent relative humidity until cotyledons emerge. Avoid excess humidity later in the plug production, as this will create conditions favorable for disease incidence.
Growing on, use a media with a pH of 5.8-6.2 and a medium initial nutrient charge. Keep light levels as high as possible while maintaining temperature at 60-75° F days and 55-60° F nights. Under garden/landscape conditions, Clear Crystal requires full sun; however, partial shade may be beneficial for retail shelf life.
Starting one week after transplant, apply fertilizer at 175- to 225-ppm nitrogen using predominantly nitrate-form fertilizer with low phosphorous. Excessive fertilizer levels will result in large, lush leaves and smaller flower count.
Alyssum is susceptible to downy mildew. A preventive fungicide application for damping off is recommended. Avoid using copper-based fungicides.