Late Season Hebes for Northwest Gardens

By: Neil Bell

Neil Bell is a horticulturist with the Oregon State University Extension Service in Marion and Polk Counties, where he oversees…

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Hebe ‘Violacea’

Hebe ‘Violacea’

The majority of species in this genus, about 100 including undescribed species, are endemic to New Zealand, with a few others found in Australia and South America. The genus includes plants of shrubby and sprawling growth as well as small trees and has natural habitats ranging from coastal to alpine.

Yvonne Cave and Valda Paddison, The Gardener’s Encyclopaedia of New Zealand Native Plants

For plant enthusiasts in the Pacific Northwest, fall has never represented the end of the gardening season but rather a time of transition following the flush of growth and riot of color that is summer. Fall is the quiet season, and foliage takes center stage, especially the change of color in deciduous leaves. Less often considered are fall-blooming plants, those that are in their peak in October and November, and perhaps even into December. Asters, roses, and other flowers of late summer are nearly finished, and it is too early for hellebores, wintersweet (Chimonanthus), sweetbox (Sarcococca), and the many other plants that flower in winter. The list of plants in full bloom in fall is fairly short. Grasses come to mind, and the curious blossoms of toad lily (Tricyrtis). A favorite often found in older gardens is false holly (Osmanthus heterophyllus), whose floral scent can be detected from far away, even on rainy days.

A genus less often considered for fall bloom and winter color is Hebe. I attribute this to the fact that, of the many hundreds of Hebe cultivars, only a few have found their way into cultivation here. Although the main flowering period for most cultivars is summer, there are some that reserve their show for the fall, and a number that rebloom significantly after their initial spring bloom. Hebes are renowned for their foliage, but less widely known is that a few show a dramatic color change in their leaves as the season progresses from summer to winter, much like certain conifers. A number of the more interesting cultivars are now trickling into nurseries and into the hands of sharp-eyed gardeners. What follows is a description of some of the best selections.

One thing to be aware of is that many of the hebes discussed are susceptible to freeze injury, particularly during the early part of fall. (This might also be a reason why so few are cultivated.) Most of the fall-blooming cultivars have in their parentage Hebe speciosa, a late blooming but tender species. The freezes of late October and early November in 2002 and 2003 were particularly hard on many of these hebes, as they were caught while still growing and flowering. Because they continue to grow essentially throughout the year, they remain tender, so a little bit of protection, from a wall or overhanging plant, will assist them in surviving such events.

Hebe ‘Purple Picture’

Hebe ‘Purple Picture’

Flowers

To Northwest gardeners, the best known of the fall-blooming hebes are ‘Amy’ and ‘Alicia Amherst’, two similar cultivars with purple shoot tips and purple to violet flowers. Both of these shrubs can reach four feet in height and width in a few years, and, if protected from freeze damage, may become much larger. These and other long-cultivated selections, such as ‘Autumn Glory’, continue to flower sporadically in the fall, but their main summer show is usually over by then. A better show is provided by ‘Purple Picture’, one of the reblooming cultivars that blossoms in June but is well-covered with purple flowers in October and November. Another purple cultivar flowering freely in fall is ‘Mohawk’, which covers itself with masses of small flowers into November. Perhaps the best of these deep-flowered selections is ‘Violacea’, which is a beautiful shrub with large leaves and prominent spikes of deep blue flowers. A rarely offered Hebe speciosa hybrid, it is worth seeking for a protected spot in the garden.

Hebe speciosa  ‘Simon Délaux’

Hebe speciosa ‘Simon Délaux’

Among the oldest selections of Hebe speciosa in cultivation are those with bright pink or red flowers. Some of these differ little from the species, although they are all likely to be of hybrid origin. ‘Hobby’, ‘Simon Délaux’, and ‘La Séduisante’ have the typical large, red-tinged leaves and long racemes of spectacular crimson or purplish flowers that are freely borne through November and sometimes into the new year (if the weather is mild). Although not commonly available, there is an array of similar cultivars, often with “pink” in their name. I have learned in growing some of these (for instance, H. speciosa ‘Pink’, ‘Pink Payne’, or ‘Pink Pearl’) that the nomenclature is confused, and these names are often synonyms for yet other cultivars. What they all share is an aversion to cold weather; they will continue to flower through a light frost, but a hard freeze will quickly bring an end to their show. Site them carefully!

Hebe 5 lewisii ‘Lewisii’ flowering in the open fields of the trial grounds in Aurora, Oregon. Author’s photographs

Hebe x lewisii ‘Lewisii’ flowering in the open fields of the trial grounds in Aurora, Oregon. Author’s photographs

If bright pink flowers are not to your taste, there are several cultivars with pale blue or white flowers. One of the showiest is ‘Bowles’s Hybrid’, a fairly hardy shrub that reaches about two feet tall and three feet wide and produces light purple flowers fading to white. ‘Sarana’ is a hybrid of Hebe recurva, from which it has inherited blue-tinted leaves; the youngest leaves develop a noticeable reddish tint in winter, and the pale blue flowers are produced into November. An erect-growing shrub to four feet, H. x lewisii ‘Lewisii’ has pale green leaves offsetting the lilac-blue flowers at the shoot tips-a beautiful plant but, unfortunately, tender.

Hebe cupressoides ‘Boughton Dome’ forms a dense mound

Hebe cupressoides ‘Boughton Dome’ forms a dense mound

Foliage

As far as foliage is concerned, Hebe is a wonderfully diverse genus; it can be hard to believe that all the species belong in the same genus. Among all the evergreen shrubs that fill our gardens, the foliage and form of hebes rate highly. Some of the best foliage forms can be found quite readily, and they include some of the hardiest cultivars. The hardiness of a hebe is inversely proportional to the leaf size: the larger the leaf, the less hardy the hebe. In their natural range in New Zealand, leaf size decreases as the genus moves up in elevation; the tiniest leaves appear at the highest and coldest elevations.

Hebe cupressoides ‘Boughton Dome’ forms a dense mound

Hebe cupressoides ‘Boughton Dome’ forms a dense mound

As a result, such well-known, small-leaved cultivars as ‘Quicksilver’, ‘Boughton Dome’, and ‘James Stirling’ are fully hardy throughout the Pacific Northwest, west of the Cascades. Each offers something different and is almost instantly recognizable. ‘Quicksilver’ is a selection of Hebe pimeleoides with a sprawling habit to two feet and tiny, silvery leaves. ‘Boughton Dome’ is a dwarf selection of H. cupressoides and forms a dense, tight mound of grayish foliage up to eighteen inches tall. Just as distinctive is ‘James Stirling’, a dwarf selection of H. ochracea that grows slowly to eighteen inches tall by perhaps two feet wide and has the same ocher-colored leaves as the species. The overall look of this one is much like that of a dwarf conifer. Another species sharing this conifer-like appearance is H. salicornioides, a shrub to two feet, with erect branches and fresh green leaves. One of the most distinctive selections is H. anomala ‘Purpurea’, which has erect branches reaching three feet tall, with each shoot tip tinged with purple. I know of no other shrub that resembles this plant.

Hebe anomala ‘Purpurea’ in flower in May

Hebe anomala ‘Purpurea’ in flower in May

Hebe ‘Silver Dollar’ with red shoot tips in winter

Hebe ‘Silver Dollar’ with red shoot tips in winter

Another smallish-leaved cultivar is ‘Silver Dollar’, a dwarf shrub to perhaps one foot in height, with gray variegated leaves. In winter, the youngest leaves at the tips of each shoot turn bright red, an effect so pronounced that it is noticeable from some distance. Displaying this same striking characteristic is ‘Sapphire’, which is a larger plant, to perhaps thirty inches tall and wide.

Hebe  ‘Silver Dollar’

Hebe ‘Silver Dollar’

If hardiness is not a concern, or you have a well-protected spot in your garden, there are a number of other choices. Among the hardier of these is ‘Caledonia’, a well-known cultivar that will flower fairly well in fall but is more valued for the reddish blue color of the shoot tips, a condition that persists through winter. The variegated selections of hebe are fairly stable but are quite tender. One of the most widely cultivated is usually offered as Hebe x franciscana ‘Variegata’, although it may be more correctly known as ‘Silver Queen’. This cultivar grows to thirty inches and has broad leaves bordered by a cream edge. ‘Tricolor’ is another unusual selection with the same broad leaves, here mottled with green, cream, and red. A larger growing plant is H. x andersonii ‘Variegata’, a four-foot shrub with slender, pointed leaves, each of which is edged irregularly with a cream border. This cultivar not only offers excellent foliage year round, but has lilac flowers in fall as well.

Hebe ‘Tricolor’

Hebe ‘Tricolor’

I have mentioned here only a few of the better forms of Hebe that I have been fortunate to grow in Oregon. These have been part of a trial at Oregon State University’s North Willamette Research and Extension Center in Aurora (Sunset zone 6, USDA hardiness zone 8). The trial fields are located in an open, windy location, and, over the last three years, quite a number of the trial cultivars have succumbed to winter cold, although some have been damaged and recovered well. These cultivars will not be hardy in exposed locations throughout the Pacific Northwest. However, with only moderate protection from a building or from adjacent plants, even the tender cultivars will survive most winters. If you provide a reasonably well-drained soil, a partly sunny or sunny location, a little summer water, and protection for the more tender ones, any of the hebes mentioned should thrive. I would encourage gardeners to try them, since, in so many respects, they are distinctive and useful additions to the garden.