Plant of the Month: Sweet Alyssum
Feb 14, 2013 04:59PM ● Published by tina
"Snow Princess" photo courtesy of Dallas Arboretum
Submitted by Jenny Wegley, Dallas Arboretum
Are you getting bored with mums, pansies, violas and kale for your fall garden palette? If they are becoming mundane to you, we have a new plant to try, hybrid Lobularia. These new hybrid forms of alyssum are much more vigorous and cold tolerant than the older varieties that have disappointed us before. The genus name Lobularia comes from the Latin name globulus, meaning small globe, and refers to the shape of the clusters of flowers. It’s a perfect name for a plant that looks like a shaken snow globe.
Three seasons ago, Proven Winners released the first vegetative Lobularia into the market. Before this, all Lobularia were grown only from seed. A vegetative product allows for a more vigorous plant with more flower power. Just one of these new plants can reach 2 feet across in a season. There are now three cultivars available. ‘Snow Princess’ was the first on the market, with narrow, dark green leaves covered in pure white, quarter-sized flower clusters. ‘Frosty Knight’ and ‘Blushing Princess’ are additions to this series this season. ‘Frosty Knight’ has white and lime-green variegated foliage with cream to white flowers. ‘Blushing Princess’ has the same characteristics as ‘Snow Princess’, but is covered in lilac flowers. Both are more compact than the original ‘Snow Princess’. Plant them in containers to add a splash of cascading color, or use them in the landscape to add mounds of foamy white flowers, like a touch of baby’s breath in a bouquet.
Plant in full sun to part shade, and water on a regular basis; all three cultivars are thirsty plants. Most likely you will find these only in 5-inch, quart, 1-gallon or larger containers. The price point will be slightly higher than that for a 4-inch seed cultivar, but you only have to buy a quarter of what you would normally buy, and the plants will last much longer in your garden. At the Dallas Arboretum, we’ve found that we can keep them all winter long if we cover with frost cloth when there is a heavy frost or freeze. For areas north of Dallas, I recommend these only for early spring or late fall color. Zone 7 winters are their limit. From Waco south, you should be good for all-winter to late-spring color. We have found these varieties also are heat tolerant enough to last all summer if given constant moisture and a little late-afternoon shade. Be sure to buy these by name at the nursery. If you don’t see ‘Snow Princess’, ‘Frosty Knight’ or ‘Blushing Princess’, avoid the temptation. The seed-grown varieties just don’t perform as well for us Texas Gardeners.
AT A GLANCE
Latin name: Lobularia hybrid
Common name: Sweet alyssum
Flowers: Quarter-sized clusters of flowers
Mature size: 4-6” tall by 18-24” wide
Hardiness: Summer and fall annual
Soil: Moist soil
Exposure: Full sun to part sun
Water usage: High to medium
Sources: Local nurseries or mail order
About the author: Jenny Wegley is the senior manager of trials and greenhouse at the Dallas Arboretum. Visit Dallas Plant Trials for more information on the Arboretum’s trials.