Illustration
Techny
Thuja occidentalis 'Techny'
Techny is grown for its foliage rather than flowers, giving the garden structure and color all season long.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Techny
Plant it in full sun. It prefers moderate water. It is hardy in USDA zones 3–7. Expect it to reach about 15 ft tall and 6.5 ft wide at maturity, in roughly 12 years (not yet checked).
What was checked
Mature height and spread, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not, and each fact above says which. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Techny
Plant Techny in spring once the soil is workable, or by very early fall at the latest: an evergreen needs its roots down well before the ground freezes. In zone 5, the middle of its hardy zones 3 to 7, that is April to June, or August on the fall side.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 5, the middle of this plant's hardy range, start with zone 5 in April. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Techny get?
15 fttall5 ft 7 inan adult6.5 ftwideSee Techny in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Techny
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Techny about 6.5 ft apart, center to center, so each plant has room to reach its full width.
Add Techny to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Techny's height, spread, hardiness zones, sun and trait tags were checked against 5 published sources on July 29, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- kb.jniplants.comJohnson's Nursery (Wisconsin) knowledgebaseheight, spread, hardiness zones, sun and trait tags
- Missouri Botanical Gardenheight, spread, hardiness zones, sun and trait tags
- Chicago Botanic Gardenheight, hardiness zones, sun and trait tags
- Purdue ArboretumPurdue Universityheight, spread, hardiness zones and sun
- NC State Extensionspecies page, sun and zones onlyhardiness zones and sun
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Techny
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note.
Safety
Foliage and oil hold thujone, a convulsant neurotoxin. Small culinary or homeopathic amounts are safe, but concentrated oil or large ingestions can cause convulsions and liver and kidney toxicity. per Evidence-Based Complementary and Alternative Medicine
Explore similar plants
You might also like
Foliage
Foliage
Foliage
Foliage
Foliage
FoliageDesign a garden with this
Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.