Sweet alyssum hybrids enhance cool-season containers, landscape beds

Richard Bogren, Owings, Allen D.  |  1/23/2015 11:03:35 PM

Snow Princess lobularia produces a cascading display of fragrant white flowers. (Photo by Allen Owings)

Blushing Princess lobularia has pale blush flowers and a less-vigorous habit than Snow Princess. (Photo by Allen Owings)

News Release Distributed 01/23/15

By Allen Owings
LSU AgCenter horticulturist

HAMMOND, La. – New plants make gardening exciting. About five years ago, a new sweet alyssum variety started appearing in trial gardens and garden centers around the country. These are now well-established in the greenhouse trade and have added a great cool-season-to-warm-season transitional plant to the retail marketplace.

Snow Princess is a unique, vegetatively propagated sweet alyssum variety known botanically as a hybrid lobularia. The Snow Princess lobularia and its cousins – Blushing Princess, Dark Knight, White Knight and Frosty Knight – are exceptional in the landscape, containers and hanging baskets. All of these varieties are from Proven Winners. Each has more durable heat tolerance than our typical sweet alyssum and has a more extended bloom season. Snow Princess lobularia is being considered for Louisiana Super Plant recognition.

Snow Princess lobularia is extremely vigorous. And because it's sterile, no seeds are set, and plants keep blooming. Deadheading – removing old flowers – is not needed. Typically the plants do well in south Louisiana from midwinter (December-January) through early summer. They are also great for fall planting.

Snow Princess has fragrant mounds of white flowers, which are larger in cooler weather and smaller in warmer weather. It can be used as a perfect filler in combination plantings and works well in window boxes.

Blushing Princess lobularia debuted shortly after Snow Princess. Flower colors are blush instead of white. Cooler nights bring about more blush tinges to the flowers. Blushing Princess is less vigorous than Snow Princess, as are all of the Snow Princess cousins.

Frosty Knight lobularia has 50 percent the growth vigor of Snow Princess and has variegated foliage. Frosty Knight is a sport – or natural mutation – of Snow Princess. Dark Knight is new and has deep purple to purple flower colors. White Knight has white flowers and major flower power.

Lobularias need moderate irrigation in containers and prefer evenly moist soil, whether in pots or in landscape beds. Plants can show drought stress but have good bounce-back potential from drying out.

Try not to over-plant these in containers. Having too many plants in too small a pot will lead to higher water demand. In containers, an application of continuous-release fertilizer at planting is best. To help maximize performance a water-soluble fertilizer can be applied thereafter. Prior to adding plants to the landscape, a yearly topdress application of new landscape garden soil or compost helps refresh plant beds.

Other new sweet alyssums also are on the market. The lobularia Stream series is bred by Danziger and originally came in four beautiful and fragrant colors – Lavender Stream, Silver Stream, Summer Stream and White Stream. Two new varieties were added in 2014 – Purple Stream, a dark purple that will not fade, and Bicolor Lavender, which has a mix of lavender, white and a hint of yellow colors to the blooms. These two are fragrant also.

Now through early spring is still a good time to add these nice cool-season-to-warm-season transition plants to the landscape bed or patio container. Some hanging baskets would also look nice. Lobularia is also favored by bees, butterflies and other pollinators. These unique plants are some of the newer flowers that all home gardeners should consider using.

You can see more about work being done in landscape horticulture by visiting the LSU AgCenter Hammond Research Station website. Also, like us on Facebook. You can find an abundance of landscape information for both home gardeners and industry professionals at both sites.

Rick Bogren
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