Quercus garryana var. garryana

Oregon white oak. A monarch of a tree locally native and forming Oak Savanna communities in the Willamette Valley that preceded European development. Slow growing tree of great age and grace. Deep green foliage forms dappled domes in the high rounded canopy. Birds and wildlife adore this completely summer drought adapted tree. To 130′ but not in your lifetime. Our acorn source is local. Whitish bark in patches and it will often develop pure white patches at the base- an outlet for sodium from the constantly saturated Oregon winter soils. Tolerates the most impenetrable clay and shuns summer irrigation. Fall color is russet orange. Grows just 2′-3′ a year in youth -if really happy. This as all oaks has what are referred to as banner years. In certain years huge amounts of acorns are produced. This is thought to overwhelm predators and at least a fair amount can germinate.  Famous for its moss covered enormous branches which have been likened to the perfect depiction of a Grimm’s Fairy Tale.  Oregon native plant.

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Quercus hypoleucoides

Silver Leaf Oak from Arizona is a favorite tree at Xera. Tall, rounded evergreen tree with skinny but thick leaves that are sage green on top and silver white on the underside. Its handsome all the time and even prettier when the gold catkins protrude from the foliage in spring. Naturally develops a straight trunk. Fast growing tree in our climate to 35′ in 12 years. Casts dense shade but tolerates limited summer water. Extraordinarily  cold hardy. It has endured subzero readings in Eugene without injury and I even encountered one in a garden in Denver. The leaves were kind of toasted from the previous winters -17ºF(!) but it was obviously thriving. Native to the mountains of SE Arizona at very high elevations and that translates to LOVE for our climate. Exceptional leaf form and shape. Be aware that in time this tree can cast quite dense shade. Wonderful on hot summer days but also inhibiting sun loving gardening. Makes you think. Wonderfully pest and disease resistant foliage- it always looks good.

Photo credit: Amy Campion

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Quercus rugosa (SW Form)

This is a remarkable oak whose geographic center is in high elevation Mexico. There are several forms of this evergreen tree with remarkable qualities. Its range extends from the SW U.S. south throughout Mexico into northern Guatemala. This southwest form has shown great cold hardiness and adaptability. These are started from acorns in a garden in Medford. The parent tree was pole straight with a boisterous green rounded crown. It is remarkably tolerant of drought and is cold hardy reliably to 0ºF. Full sun in  average soil for a moderately fast growing tree. The outline of its crown is oblong at first and if you remove the lower limbs it will send the crown skyward. As I said the trunk was pole straight on a tree that was 35′ tall (18′ wide) and very pretty. Doing research on this tree it was found in California that this tree literally collects pollutants from the sky with its rough leaves. Its proposed to be planted along intersections and freeways  and could be a boon to lower the particulate count.  Dark green foliage looks good year round.  Water to establish and then none in subsequent years. Grows fast for an oak and it really adores our climate. The bark is rough with gray striations. It  makes many acorns and this should be taken into account in siting. Good candidate for a street tree or a garden shade tree. Average soil, including clay soils. Full sun from every direction for the straightest tree. Syn. Quercus reticulata. This would also be a good candidate for a formal large screen. Sometimes called net leaf oak or southwestern net leaf oak. Casts moderately dense shade with time.

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Quercus suber

Cork oak. The commercial source for high quality cork comes from this evergreen mediterranean native. A large growing tree with a rounded crown. To 35′ tall and half as wide. As the trunk grows (expands) it develops the corky bark very quickly. Harvest correctly and it does not harm the tree. In mid-spring golden tassels eventually become acorns- loved by wild life. Frequently planted as a street tree in the city of Portland. Very, very drought tolerant, in fact it really should not see any water during the summer. Eventually casts a good amount of dark shade. Beautiful tree that is amazingly adaptable to freezing rain and snow. Grows about 2′- 4′ per year when established. Very climate adapted.

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Quercus wislezenii ‘Dense Form’

I collected the acorns of this tree near  Lake Isabella, CA in the southern Sierra Nevada. It was a particularly handsome form of what can be a less than majestic species. Densely foliaged with a straight upright trunk about 25′ tall with a rounded crown. Wow. We hope the progeny are as cool. Interior Live Oak of California. Evergreen tree to 25′-35′ tall with a spreading crown. Was native in Oregon in the past as hybrids known as Mohr Oaks (Quercus kelloggii x Quercus wislezenii) still can be found. Hardy to short shots to 0ºF. Grows about 2′-3′ a year in youth. Water to establish the first year then none in subsequent years.

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Sycopsis sinensis

Rare and somewhat obscure evergreen tree that belongs in the Hamamelis family. Graceful medium green tapered leaves fold neatly over each other in a pendant habit. The branching structure itself is graceful as well. To 18′ tall  with a columnar habit at first and then spreading a bit with time. In winter curious flowers look like little red brushes and occur profusely.  Nice looking cold hardy, shade tolerant and extremely drought adapted small tree. WE love this tree and have been incredibly impressed with how tough but beautiful it is. Accepts regular water in summer as well. Ideal sized tree for small gardens, or the space in-between the new close together construction. Not an oppressive evergreen but rather light. Moderately fast growing.

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We have been so impressed with the performance of this small evergreen tree species that when we saw this charming narrow leaved form we snagged it. An upright growing but not wide tree to 18′ tall. The thin leaves are 4mm wide but up to 6cm long and are thinly produced so that the tree has a fine texture and is even better to view the late winter and early spring red brushy, flowers. Moderately fast growing it is also very drought tolerant. Water to establish and in summer  or to speed growth otherwise it can get by on natural rainfall. Very neat and tidy and cold hardy to -5ºF.  This tree is a good candidate for areas affected by subfreezing east wind- its exceptionally tolerant of that for a broad leaved evergreen. Full sun to high overhead shade ( with less of the red flowers). In time the cut branches can be brought inside and forced into bloom for arrangements. Not deer food, but i’m not as familiar with this form. Unusual, tough and beautiful. Narrow leaved Sycopsis.  Tolerates many soil types including heavy soils in upland situations. SW China

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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.

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Trachycarpus fortunei var. wagnerianus

Waggies! Our fave hardy palm at Xera. The fronds on this slower growing tree are stiff and tidy and have none of the drooping filaments on the branch tips that the species T. fortunei possesses. To 12′ tall in 7 years. A very clean and tidy looking palm with a distinct asian look. The fronds are even finely outlined in white hairs…more definition for this stately plant. Grows about 2′-3′ a year if well watered. You really can’t water Trachycarpus too much in the ground, it just makes them grow faster. Same wooly trunk as the species. Waggies are recommended for windy cold areas as they are not affected by those conditions. Fantastic cold hardiness not suffering damage until temps dip below about 5ºF.  This is a great palm for colder gardens and tolerates quite a bit of shade. Always looks it’s clean best.

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