Heat Tolerance Sets New Alyssums Apart

Proven Winners' Princess and Knight lobularia collections thrive in areas with lots of sunlight,

The  goal of Proven Winners’ lobularia breeding program was to bring a fragrant, easy, all-season performer into a crop that previously had a very limited range of success. The Princess and Knight collection of hybrid lobularia look like sweet alyssum, but appearances can be deceiving.


Where old-fashioned seed-type alyssum do well only in Mediterranean climates, quickly dying in the summer in all other parts of the country, these new hybrids thrive in the heat. They have received top marks for performance in summer trials across the Southern U.S., including the Dallas Arboretum in Texas and Costa Farms’ trials in Miami, Fla.

While there have been many knock-off genetic lines introduced over the past three years, none of those boast the record of performance of ‘Snow Princess,’ ‘Blushing Princess,’ and ‘Frosty Knight.’ While these plants may look the same, the plants in this Proven Winners collection do not grow or perform like any other lobularia.

Production Information

‘Snow Princess’ and ‘Blushing Princess’ are vigorous — almost too vigorous for a 4-inch pot — but they make amazing hanging baskets. They also thrive in gallon containers and can be produced easily in 5- to 6-inch pots. This is ideal for retailers wanting to provide an easier plant for the customers to use in custom mix containers.

If you use growth regulators, 4-inch production can be very easy. Simply apply Sumagic spray at 5 ppm three weeks after transplant. Bonzi at 1 to 2 ppm is a good holding drench for nearly finished material, and growers can also use a Topflor spray at 10 ppm. All respond to DIF for control of stem length, and the highest light levels will also help to control growth.

A note on watering: Since these plants are luxuriant growers, they require a lot more water than the old-fashioned forms. Don’t be surprised if they need a lot of water once they begin actively growing. When producing hanging baskets, give some thought to what crops will be below. ‘Snow Princess’ and ‘Blushing Princess’ bloom constantly, and the old flowers will drop. Plan ahead to make sure whatever you grow beneath them will tolerate some snowfall. Keep in mind that the color intensity of ‘Blushing Princess’ is based on light intensity and temperature. The brighter the light and cooler the nights, the deeper the color will be. Flowers open silvery lavender, and the colors deepen as they age, so make sure you have high light levels for the best plant and flower quality.

‘Frosty Knight’ has a more traditional vigor and will take the same amount of water as most bedding plants. The variegation of the foliage reduces the vigor somewhat and also makes for a plant that will sell based on the foliage impact as well as the flowers. Bright light is still the key to producing the highest quality plants and the most flowers. ‘Frosty Knight’ makes a beautiful combination with all bedding plants and provides a great foliage interest for early sales.