Q: My question is about what is termed “perennial” (according to a Raleigh garden center) lantana, which I planted three years ago in my Sandhills garden. It has returned each year and is huge. However, it does not produce blooms until mid-June at the earliest. In the fall, I cut it back to about 12 to 18 inches and am wondering if this is resulting in it being a late bloomer.
A: Lantana is certainly not top hardy here in most of North Carolina. I generally recommend gardeners to not cut it back at all until spring when new growth starts at the base and then to cut it back hard. The twiggy stems will help hold in some heat during very cold nights and add to the plant’s hardiness. At any rate, flowering getting going by mid-June is typical and should continue to fall.
Will this plant survive the winter?
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Q: Will orange peel cestrum overwinter in northern Wake county? I have had two over the past two years. They performed beautifully. However, neither survived the winter. One winter was harsh and one was relatively mild. Any thoughts?
A: Cestrum ‘Orange Peel,’ known as willow-leaf jessamine, is purportedly a hybrid between C. diurnum and C. nocturnum, the day- and night-blooming cestrums respectively. Since both those species are white flowered, I have my doubts and think that the orange C. aurantiacum probably has something to do with the cross. For those unfamiliar with this plant, it makes a large, deer-resistant shrub to 10 feet tall and 8 feet wide topped from late spring through fall with rich, orange-yellow flowers in dense clusters.
In northern Wake County, you are at the very limits of its hardiness. The plant is generally listed as a zone 7b plant, which means it should be hardy to a low of 5 degrees. (Zone 7b extends from Raleigh to Charlotte.) My experience with this plant says that anything below about 8 degrees will kill it back to the ground, but it will re-sprout in spring to make a good sized shrub.
One key for increased winter survivability is to plant it in a well-drained, sunny spot as it does not appreciate excess winter moisture. If you have had trouble with the plant, get it in the ground early in spring to give it plenty of time to develop a good root system in case it is killed to the ground. Mulch it well before winter and don’t be too quick to compost it in the spring. It will need some warmth to start growing again.
An Ant Problem
Q: I have a problem with ants invading many of the potted plants I have on my paver stone patio and cement walks. Do you have any suggestions or solutions to help me with this problem I’ve had for many years?
A: I didn’t have a good answer for you so I checked in with one of N.C. State University’s experts, entomologist Steven Frank. Unfortunately, he didn’t have a great answer either. There are some commercial products specifically formulated for fire ants or as a perimeter protection for your house for multiple species of ants (I have used Amdro products for fire ants in our nursery). If you are planting annuals in your containers, using new, clean soil each season and raising your pots off the ground will help. Smaller pots can be immersed in tepid water to get rid of most of the ants if you are dealing with already infested plants. Sprinkling diatomaceous earth on top of your pots and around the base will also deter ants from setting up shop and can ultimately kill off populations in your pots.
Mark Weathington is the director of the JC Raulston Arboretum at N.C. State University in Raleigh. Info: jcra.ncsu.edu. Please send your garden questions, including the city where you garden, to: firstname.lastname@example.org.
Common name: Willow-leaf jessamine
Botanical name: Cestrum parqui
Family: Nightshade (Solanaceae)
Category: Flowering shrub
Primary uses: Shrub borders, perennial beds
Dimensions: 5-8 feet tall by 4-6 feet wide
Bloom time: June to September
Bloom color: Mustard yellow
Hardiness: 5 degrees (USDA hardiness zone 7b)
General attributes: Willow-leaf jessamine makes a large, multi-stemmed shrub with narrow, lance-like leaves. From mid-summer to frost the plant is covered in sprays of small, tubular, mustard-yellow flowers which attract hummingbirds by the droves. The flowers have little fragrance until the evening when they will scent the entire garden. The flowers are followed by showy, glossy black bead-like fruits. In cold winters and at the northern end of its hardiness range, this plant will die back to the ground. Expect it to quickly reach 5 feet tall and flower well by early summer of the following year. Plant this South American species in full sun and a relatively well-drained soil.