The white flowered form of culvers root- but seldom called that in the PNW. Slender perennial with multiple vertical stems clad in symmetrically space pointed foliage surrounding the stem. At the tips in early summer multiple spires of pure white flowers give a really cool ethereal effect. Massed it is simply one of the coolest plants. Our form rises to just 4′ tall and forms slowly increasing clumps. In autumn the foliage that lines the stems often turns bright yellow and remains for a while- a second season of interest. Full sun to the very lightest shade in any soil of good fertility. Does well even in unamended clay as long as summer water is dependable. Long lived perennial that never requires division or fussing. Cool cut flower for big wild arrangements. Bees love it.
Biome: Hot Aspects
Its surprising in our climate that heat is as big of an issue as it is. But there are scores of sunburned and toasted plants littering our city by the end of summer. We average just 2.o” of rain during June-August and you have to take into account reflected heat. That could be heat emanating from an asphalt street such as occurs in a hellstrip or the accumulated heat of a hot wall. Both can conspire to fry plants. Luckily, we grow a LOT of plants adapted to excess heat. These plants won’t fry on the first day above 95ºF. Some plants revel in reflected heat, they come from hotter climates and need warmth to both bloom and to ripen wood for winter. That means it receives enough heating calories to ensure winter hardiness. Currently, Portland averages 14 days above 90ºF per year. By the next decade that number will have more than doubled. Part of gardening with climate change is to anticipate those effects and adapt to them. Increasingly, we will be considered a hot summer climate. We should garden accordingly.
Climate Adapted Plants for Gardeners in the PNW
Spring bouquet viburnum or Laurusitinus is a common shrub in our climate. This form lightens up what can be a very pedestrian plant. The edges of the evergreen leaves are margined in cream with an interior of soft green. This makes a shrub that glows year round and can be used to lighten up dark corners. In autumn clusters of pink buds form and hold until mid winter. Then as the days begin to lengthen it opens these clusters which are lightly fragrant and white. Strong growing shrub that requires very little water once established. To 8′ tall and 5′ wide in 6 years. Full sun to part shade to high overhead shade. Nice looking, tough shrub native to the Mediterranean very easy to grow and long lived. If a green sport appears simply prune it off to the base to retain the variegated form. Water to establish. Not deer resistant. Excellent backdrop to a mixed border or trimmed into a contained hedge. Nice fast growing screen. Blue berries sometimes follow the flowers. Buds and flowers put on a show for months. Blooms on wood from the previous season prune after flowering if needed. Naturally dense and rounded.
Viola corsica
One of the parents of modern violas this perennial is short lived but while its around its never out of bloom- year round. Slender indigo blue flowers are small but profuse on a compact plant to just 6″ tall and barely wider than that. Seeds itself around prolifically…how the seeds find their way so far from the parent plant is natures mystery. It will germinate anywhere – cracks, beneath rocks. Sun, Shade. Very hardy to way, way below 0ºF. Light summer water during the hottest weather. Part shade in nearly any texture soil. Mediterranean wild flower.
Vitex agnus-castus ‘Sensational’
Excellent California selection of Chaste tree with thicker, bluer flowers. Large growing shrub with aromatic finely divided leaves in mid-July in PDX spires of blue flowers erupt from each branch tip. It remains in bloom for 3-4 weeks. And if you remove spent flowers more will appear. Full sun and poor to average well drained soil. No summer water when established. Attains tree-like status with great age. May be pruned back hard in spring to contain the ultimate size. Blooms on new wood. Long lived and hardy below 0ºF. Leaves appear late in spring- often not until mid-May. Be patient. Loved by pollinators and bumble bees specifically. A shrub in full bloom will be a haze of drunken bumbles who after a day of working will often fall asleep in the flowers of this shrub. Tolerates the hottest sites and is very long lived.
Watsonia latifolia
A true red flowered Watsonia and one of the hardiest of the genus. Wide green spikey leaves rise to 2′ tall in spring. In late spring to early summer 3′ tall spikes of tubular true red flowers line the stems. Loved by hummingbirds and cut flower aficionados alike. Rich soil in full sun in a protected position- a south or west facing wall is ideal. Freezes to the ground below 20ºF- re-sprouts in spring. Forms an expanding clump to several feet across. A fun genus to experiment with in our climate. Rated as zone 7 in its native high elevation South Africa. We think its more like 10ºF in our climate. Plant with royal red Lobelia tupa and Rosa ‘Bengal Fire’ for a red extravaganza. Excellent performance at the Oregon Coast. Somewhat deer resistant.
Watsonia pillansii
This is one of the hardiest species of Watsonia Lily. It forms large evergreen clumps of spikY foliage to 3′ tall. In early summer 6′ spikes of tubular brilliant orange flowers are stunning. They bloom for weeks. A protected location such as close to a south or west facing wall. Capable of freezing to the ground in extreme cold (below 20ºF) but regrowing vigorously and still blooming in late spring to early summer. Rich, well drained soil with regular summer moisture. If allowed to go completely dry in summer this as with other Watsonias will go dry dormant. It returns with the first rains in autumn. Amazing cut flower. Mulch your clump in autumn. Wonderful South African perennial that is glorious at the Oregon Coast. To 3′ wide eventually.
Watsonia x pillansii ‘Coral and Hardy’
We love Watsonias but the most successful climate is truly on the coast. This form is seed from a persistently hardy, well blooming plant that has survived in Portland. The majority of these seedlings will be coral/ orange/ light pink. To 20″ tall forming clumps in RICH, well composted soil in full sun. Regular summer water increases both the growth rate and the cold hardiness. Larger more established clumps are hardier to cold. Amazing cut flower that will produce several dozen spikes off of one good clump. Mostly evergreen. Foliage looks burnt below 20ºF and can freeze to the ground. This winter growing bulb is also immensely drought tolerant with a period of summer drought inducing dormancy. Place in a warm, protected location Near a south facing wall or fence. Mulch for the first few winters with dry leaves. Place in a location where summer dormancy is not an issue. Very fun to grow South African bulb. Excellent performance at the Oregon Coast. Not bothered by deer or elk- well the elk might step on them but they won’t eat them. Fantastic cut flower and clumps become huge there.
Xera Plants Introduction
Wyethia angustifolia
Mules Ears are rare in cultivation. These cheery bold perennials make the transition of our wild flowers from spring into real summer. So named for its long leaves it forms very permanent spreading colonies in clay soils in habitat. The brilliant yellow sun flower blossoms rise up on sturdy stems directly from the ground. Each ebullient large flower is about 4″ across. Blooms appear from late April to early June. This plant usually finishes blooming just as summer drought commences. Its a memorable sight in wild meadows where it blooms simultaneously with native Rosa nutkana and Farewell to spring (Clarkia amoena var. lindleyi) and Giant blue eyed mary (Collinsia grandiflora). Wonderful cut flower and immediate and popular pollinator perennial. This plant was once very common in the Willamette Valley but civilization has immensely shrunk its native range. Good, long lived garden plant that goes summer dormant quickly after blooming has ended. The leaves turn gray and brittle and can easily be removed then. Give it a summer rest w/ little to no summer water once established. Full sun to very light shade. Water to establish its first season then none in subsequent years. Fun to grow and LONG lived. To 14″ in bloom forming a plant several feet across. Moderate deer resistance. Native to the Portland city limits. Very slow to finish in a salable size. Patience. Limited quantities. Oregon native plant
Yucca (nana) hermmaniae
Adorable and rugged little dwarf Yucca from southern Utah. Tight round quills are decorated with filaments on the leaf edges. Not a friendly guy and very slow growing. Forming spheres of spikes to 1′ across and multiplying to produce colonies with pups. Full sun and very well drained soil of average to poor fertility. Requires excellent air circulation- no crowding. Plants that are smooshed with little air circulation protest heavily and it then takes a while for recovery. Open and free in rock garden conditions produces the happiest plants. At home nestled with boulders or as a finer texture element with Agaves. In time it produces adorable and conical shaped hoods of flowers- a gnome wedding. Excellent in containers- open, well drained containers. Light summer water during hot weather seems to speed growth. Locate away from paths. Owwie. Strongly deer and rabbit resistant.
Yucca rostrata
Beaked Yucca does fantastically well in our climate and is one of the Yucca species that will form a dramatic trunk. Blue thin leaves radiate out in a perfectly round orb. Slowly rises to 8′ tall in our climate. Full hot all day sun in a warm position. Very well drained soil with light summer water during the hottest stretches to encourage growth. Occasionally, with age 4′ spikes appear holding large trusses of ivory flowers. Perfectly hardy to cold, way below 0ºF. Avoid cold wet sites- to really do well it needs heat and exposure. Not prone to bacterial leaf blight that affects other Yucca species. Good air circulation. Lives happily in large containers for eons. Focal point in many of the best gardens in our region. High deer resistance. Evergreen.