Silver Germander is a wiry shrub with gray foliage and even lighter gray/white stems. All summer it bears pale blue small flowers with a prominent central lip. Traditionally used in topiary or as a trimmed hedge, it takes amazingly well to heavy shearing. It responds by becoming incredibly dense. Its malleability leads people to also trim it into any whimsical shape they can dream of. Full sun, average, well drained soil. Little to light summer water when established. Requires full sun and a hot position with protection from subfreezing wind. Classic mediterranean shrub. Grows as well at the cool coast as it does in the hot inland areas. To 4′ x 4′ if left unpruned.
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
Thymus vulgaris ‘Peter Davis’
Form of the useful culinary herb that is also a nice looking little evergreen shrublet. To 6″ x 6″ the gray green foliage is aromatic and most useful before it blooms. In early summer it becomes a ball of light pink flowers- very pretty. Wait a bit until the blooms have receded to harvest again. A first rate, semi-woody evergreen garden plant that is good looking for most of the year. Average to rich, well drained soil in full sun. Light summer water. Very easy go grow. Takes quite a bit of drought when established.
Tigrida x pavonia
Is this hardy? Why, yes, yes it is. Mexican Shellflower or just Tigridia is a fun bulb that produces large, immensely showy flowers that last but a day. Three large petals emanate from a wildly speckled center. White, red, orange, yellow, and pink flowers are all represented in this mix. Rich, well drained soil in a warm position- mine are on the south side of my house in average soil and they not only multiply year to year they self sow. The wonderful flowers appear individually for weeks in mid to late summer. Add a handful of all purpose fertilizer when planting and water consistently through bloom. Full sun- no fudging here. Very easy to grow. To 20″ tall in bloom on average. Flowers 3″ wide. -Emerges late in the spring- usually mid-May. Patience.
Trachelium caeruleum
Flossflower- this short lived perennial is a wonderful long blooming plant. Umbels of blue flowers rise to 20″ tall. Remove the first set of blooms and it will sprout vigorously from the sides, rows of flowers. Loved by butterflies and pollinators in general. This Mediterranean native has been raised as a cut flower forever, blooming continues to October if you remove spent flowers. They last in a vase for a week or more and deliver a light, sweet fragrance. Freezes to the ground below 20ºF, and is root hardy to about 10ºF. Typical lifespan for an individual plant is 3-5 years but it almost always guarantees seedlings which will sprout in adventitious places. Full sun to very light shade and rich soil with light consistent summer water. It may go very dry and recover from a deep soak. Very easy to grow plant for spectacular effects. Perennials borders, cutting gardens. Hummingbird manna. Forms arching clumps. A distant relative of Campanulas. Rich soil and regular water guarantees a much larger, bloomier plant that will have a longer lifespan.
Trachelium caeruleum ‘Dark Purple’
Florists variety of Flossflower that we think makes a nifty garden plant too. Large rich violet umbels repeat through summer. Remove spent flowers to encourage more. Full sun and rich, well drained soil. Lightly fragrant and a stupendous cut flower. To 30″ tall and 20″ wide. Deep green foliage and black stems are handsome. Short lived perennial- approximately 3-4 years per plant. Freezes to the ground below 20ºF- resprouts from the base if temperatures never drop below about 10ºF. Often self sows in open disturbed sites- even following hellacious winters that compromise the parent plant. Best in rich, soil that drains, double dig the soil to incorporate oxygen into the root zone and allow water to penetrate deeply. Light summer water- extends bloom. If you cut the main bloom on each stem- and it will last for 10+ days in a vase, the sides of the plant will erupt in further bloom and continue to autumn. Loved by butterflies who find an accommodating landing pad and copious amounts of nectar filled flowers. Iberian peninsula and Mediterranean.
Trachelospermum asiaticum ‘Chirofu Chirimen’
Cool little Asian Star Jasmine with tiny variegated leaves that forms dense mounds as a ground cover or in time it can reach up as a cute and not strangling vine. Each leaf is margined and splashed with white. New growth has distinct pink tints for a distinct multicolor effect. Forms a fine textured plant but as a small scale ground cover it will block weeds. To 1′ tall x 30″ wide as a ground cover. To 8′ tall or higher as a self clinging vine in wind free places. Rich, well drained soil with regular summer water. Definitely double dig the soil before planting to incorporate oxygen as well as assist in absorption of water. Add organic fertilizer as well. Trachelospermums appreciate good drainage and regular summer irrigation to do their best. Otherwise drought tolerant but slow growing. Nice on fences or screens or up the trunk of a Trachycarpus (Windmill Palm). Good deer resistance. Evergreen.
Trachelospermum asiaticum ‘Variegatum’
Variegated Asian Star Jasmine. Excellent evergreen ground cover with playful foliage that looks great year round. Lovely entire leaves are spaced and outlined in cream. Great contrast to the sage green leaf interior. Trailing ground cover (occasionally it can rise up to be a vine- in windfree locations with support) but mainly its value is a year round showy and consistent look. Mounding and trailing it will root into the ground when it feels like it. To 10″ tall and 3′ wide as a ground cover. To 10′ tall as a vine. Full sun to dense shade in rich, well drained soil. But it adapts to harsher sites if given regular water. Excellent under trees, shrubs. Dense enough to discourage weeds. Very cold and drought tolerant. Seldom blooms. Moderate deer resistance. This and all Trachelsospermum asiaticum have two distinct forms of foliage. Juvenile and adult. Juvenile foliage is associated with long trailing and vining material. In wind free, still locations it can rise up as vine and thats when it becomes adult. This plant ONLY BLOOMS ON ADULT foliage. So, that is one reason you seldom see flowers on Asian star jasmine. Over time adult foliage will appear on ground covers. Its less vining and more bushy. Again, until adult foliage forms there will be no flowers.
Trachelospermum jasminoides ‘Madison’
Reputed to be a hardier form of Star Jasmine, we really haven’t witnessed that. It seems just as hardy as the commonly grown clone. But it has several important differences. The large deep green leaves are conspicuously convex and thick. In June to September it alights with tons of ivory colored sweetly fragrant pinwheel shaped flowers. These are slightly smaller but come in such fragrant abundance that it doesn’t seem to matter. Evergreen from the base to the top which is nice. No bare knees. Full sun to quite a bit of shade in rich, well drained soil. Summer water speeds both growth and early establishment. Then light regular summer water. Moderate deer resistance. Twining to 15′ provide support. Fences, pergolas.
Trachelospermum jasminoides ‘Variegatum’
Nice form of star jasmine with large sage green leaves edged in cream. New growth emerges a very pretty pink. From June to August a continuous supply of clusters of sweetly fragrant ivory flowers. To 12′ tall and twining. Provide sturdy support. A nice attribute of Star Jasmines is their habit of keeping their foliage densely to the ground- never any bare knees. Takes full sun to quite a bit of shade- and still blooms. Slightly more tender than the species it requires a protected location- against a wall is ideal. Regular summer water speeds growth and this intensifies the re-blooming. Evergreen. Moderate deer resistance.
Trachycarpus fortunei
A classic palm in the PNW. Windmill Palm or Trachys as they are also known are extremely popular. And they should be. Moderately fast growing palm to about 18′ tall in 10 years. The trunk is covered in fur and this acts almost like insulation to protect the interior meristem from cold. Very cold hardy to near short dips to 0ºF- many venerable and ancient Windmill Palms can be found in old neighborhoods having gone through the very worst winters of the last 50 or more years. The fronds usually have drooping filifers on the species but that can vary. Male and female and requires one of each for viable fruit set. Following huge aromatic cream colored flower structures pollinated berries drop and will often germinate in open ground. Full sun to full shade. Drought tolerant but regular irrigation in rich soil will speed growth. Excellent performance in tight spaces. Occasionally young palms become nitrogen starved and turn yellowish. To correct simply feed with all organic fertilizer and mulch and water well through summer.