Attractive Addition to Russian Sage Selections

Perovskia atriplicifolia ‘Denim ‘n’ Lace

 

Proven Winners ® has introduced a new Perovskia atriplicifolia called ‘Denim ‘n’ Lace’. The plant has all the growth and hardiness characteristics of other Russian sage, but at 28”-32” (71-81 cm) tall, it is somewhat shorter than the species. Denim ‘n’ Lace is also more upright than the species, making it a perfect selection to tuck into limited space.

Visually, the most distinctive feature of Denim ‘n’ Lace is the shorter internodes, making the flowers grow closer together and giving the plant a bushier look rather than an open, airy look. The foliage is the classic cut-leaf gray-green typical of Russian sage, but the flower color is almost identical to Nepeta ‘Walker’s Low’—in other words, somewhat deeper in color than the species Russian sage. In bloom, it looks more like a perennial than a small shrub.

Denim ‘n’ Lace flowers

 

Denim ‘n’ Lace needs full sun (at least six hours sun per day) and dry to average well-drained soil. Pest problems are similar to other Russian sage. The plant starts blooming in late June in Zone 5 and continues to bloom throughout the summer. Old foliage can be pruned away in early spring.

Golden Vicary Privet

Here’s a fun plant to use in a mixed border or as a pair of accents by an exterior door. In full sun, the leaves are lemon yellow; in semi-shade locations, or where lower branches are shaded, the leaves are apple green. Each leaf is approximately 2″-2 1/2″ (5-6 cm) long and has a shiny surface.

Golden Vicary Privet (Ligustrum x vicaryi) can reach a height of 6′ (2 m), but more commonly is 3′-4′ (1.0-1.2 m). The width is about equal to the height on plants under 3′ (1.0 m), but, as with all privets, can be regularly sheared to the desired shape.

In the four years that I have owned my plant, I have never noticed insect pests. The foliage may develop purplish leaf blotches from too much rain or from overhead watering.

Golden Vicary is hardy in Zones 5-8 and is drought resistant once established. It has a naturally dense, rounded structure. Early spring is the preferred time for any hard pruning to maintain the desired overall shape. The shrub is late to leaf out, so don’t prune out dead branches until late May. Any well-drained soil, plus a location with at least morning sun, is ideal for the Golden Vicary Privet.

In addition to varieties of yellow barberry, Golden Vicary Privet provides a splash of yellow in the garden all season, even while yellow-flowered perennials go in and out of bloom. The white flowers are insignificant, but the elliptical leaf shape is a pleasant contrast to the strap-like leaves of daylilies and the feathery leaves of threadleaf coreopsis.

Plant of the month: Spiraea japonica ‘Little Princess’

Few shrubs are as spectacular in bloom as established plantings of Spiraea vanhouttei (Bridal Wreath Spirea). Not all of us have room for this magnificent bloomer, but breeders have worked diligently to develop smaller spirea with three-season interest. Two of my favorites are Spiraea ‘Magic Carpet’ and Spiraea ‘Little Princess’. Both plants are 2′-3′ (.6-1.0 m) high by 3′-4′ (1.0-1.2 m) wide at maturity. .

The red-tipped new growth and apple-green mature leaves make ‘Magic Carpet’ something of a specialty planting. It’s best used as a focal point. For a more conservative shrub that will settle in nicely with other border plants, or as an attractive massed bed, ‘Little Princess’ is my first choice.

The leaves of ‘Little Princess’ are a darker medium green, and the shrub has a pleasant rounded shape. (If planted in partial shade, the growth pattern will be more open.) In the fall the leaves turn a soft red.

Spiraea japonica ‘Little Princess’

Instead of the washed-out, barely pink flowers of most common spireas, ‘Little Princess” flowers form deep pink clusters that gradually fade to pale pink. In full bloom, it is common for both colors to be present at the same time. Re-bloom can be encouraged by trimming back the shrub lightly after its first growth (in Zone 5, first bloom is mid-June to early July).

Spireas prefer full sun but can manage light shade. They are known for being easy to grow in some of the worst soils, and, as long as they are regularly watered in their first year, they survive well with only average rainfall. ‘Little Princess’ is hardy in Zones 4-8.

Spireas have few insect or disease problems when planted in full sun with adequate air flow. Aphids could be a problem; powdery mildew is possible on overgrown plants in humid environments; leaf spot can occur in cool, moist climates; and, as a member of the Rosaceae family, spirea is susceptible to fireblight, although the occurrence is rare.

The main issue with any compact spirea is that growth can become scraggly–smaller branches don’t leaf out, while other branches shoot up higher than normal. To keep spireas looking attractive, the plant can be cut back at any time during the active growing season. For major rejuvenation, cut back the entire plant every three years to approximately 6″ (15 cm) above the ground before plants begin to grow in the spring.

Dianthus Devon Cottage ‘Waterloo Sunset’

Dianthus ‘Waterloo Sunset’

Deep magenta pink has always been my favorite color to make all other garden plants come alive. Its intensity makes pale blues and lavender look softer. Combined with yellow and orange, magenta turns the garden into a Monet painting. It harmonizes all other pinks and makes white sparkle.

Sadly, few perennials, other than peonies and roses, are available in deep magenta; but now, thanks to the breeders at the British firm Whetman Pinks, a gorgeous dianthus is available for mid-height plantings in the herbaceous or mixed border. Hardy in Zones 5-9, the ‘Waterloo Sunset’ dianthus is a compact 12″-14″ (30-36 cm) high with airy blue-gray foliage. It has the classic carnation fragrance and ruffled petals of other pinks (so-called because the flower edges appear to have been trimmed with pinking shears). Deadheading allows the plant to bloom throughout the summer.

Dianthus ‘ Waterloo Sunset’ flower

The dianthus requires good drainage, but otherwise doesn’t seem fussy about soil. If you’re concerned about whether your soil has adequate drainage, just mound up the soil underneath the dianthus when planting, creating your own mini raised bed. Although this is a new plant for my garden, I have a couple of immediate observations:  1) It requires full sun to maintain its upright, compact habit; and 2) it requires plenty of water while it’s becoming established. Do not let the soil dry out for more than a day if temperatures are over 80° Fahrenheit.

Dianthus rarely have insect or disease issues when a healthy plant is placed in the correct location. Along with its other attributes, ‘Waterloo Sunset’ seems a major advance for this class of perennials. You should be able to find it at Home Depot in the U.S. and at garden retailers throughout the U.K.

Plant of the Month: ‘Technito’® Arborvitae

Technito arborvitae image courtesy of Charles Fiore Nursery

Thuja occidentalis ‘Techny’ (the Techny arborvitae) is, perhaps, the most handsome of the lush, dark green arborvitaes. Unfortunately, not all of us can find the right location for a 12′-15′ (3.7-4.6 m) tall evergreen. Now, however, there is a moderate sized, naturally occurring sport of the Techny, the Technito arborvitae (officially, Thuja occidentalis ‘BailJohn’).

Selected by Michael Yanny of Johnson’s Nursery, Menominee Falls, Wisconsin, the Technito was introduced by Johnson’s Nursery and Bailey Nursery, St. Paul, Minnesota, as part of their joint breeding program to produce superior cold-hardy plants. Technito is a more dense selection than Techny, with dark green foliage extending to the ground. The Technito has a compact, pyramidal form that requires no pruning, although it may be lightly sheared every 2-3 years to maintain its essential shape.

A slow growing plant, the breeders maintain that when grown in Zone 4, a 14-year old plant will become 6′ (1.8 m) high by 4′ (1.2 m) wide at the base. At maturity, Technito may achieve an 8′ (2.4 m) height.

Technito is hardy in Zones 3-7. It has no known disease or insect pests, although it is not deer resistant. The plant needs a half day to full day of sun, average to moist soil with good drainage, and it tolerates heavy clay soils. As with all evergreens, avoid locations near roads that are salted in winter. Technito is relatively new in the trade, so if you are interested in the plant but are not sure where to find it locally, try calling or emailing Johnson’s Nursery for the name of a local distributor.

Lilac Blights

A long rainy spring, such as many of us experienced this year, creates the perfect conditions for lilac blight. There are two types of lilac blights, a fungal variety, Ascochyta syringae, and a bacterial variety, Pseudomonas syringae p.v. syringae (the p.v. stands for pathogen variety and indicates a subspecies). Both varieties affect new growth on lilacs, and, since the symptoms can appear somewhat similar, we’ll look at each blight separately.

Ascochyta syringae

Ascochyta is a disease that usually affects grains and grasses; it causes large, wheat-colored  patches of dead grass on bluegrass, for example. The fungus can also appear as leaf spots on various trees, including ash, boxelder, dogwood, and walnut, among others. Before being renamed Phoma clematidina, Ascochyta clematidina was the name of the pathogen responsible for clematis wilt. So Ascochyta is a well-distributed plant pest.

On lilac, Ascochyta is sufficiently severe to cause a blight, in which the leaf spots coalesce into blotches. Eventually the blight girdles new twigs and kills the leaves. In the spring, look for symptoms on new growth, including a brown or black shepherd’s crook. This is one of the confusing symptoms, since shepherd’s crooks are more commonly seen with bacterial diseases, such as fireblight on crabapples.