Thuja occidentalis 'Filiformis' / Threadleaf Arborvitae

[Excerpt from Dwarf & Unusual Conifers Coming of Age A Guide to Mature Garden Conifers
By Sandra McLean Cutler]
long trailing branchlets with rich green foliage pressed against tight to stem creating a cord-like effect; distinctive orange-brown arching branches; amber winter foliage in colder climates; low sprawling rounded form; full sun.

Thuja occidentalis
Photo by Sandra McLean Cutler
Thuja occidentalis 'Filiformis' - Foliage The foliage of this selection is generally long, thin, and weeping at the tips. Deep green in color. Branchlets are approx. 1/8" (3.2 MM) wide and thin.
Photo by Bill Barger
Thuja occidentalis 'Filiformis' The Harper Collection of Dwarf & Rare Conifers located at Hidden Lake Gardens in Tipton, MI. Photo taken August of 2005.
Photo by Dax Herbst
Thuja occidentalis 'Filiformis' This photo was taken at Bickelhaupt Arboretum located in Clinton, IA.
Photo by Dax Herbst
Thuja occidentalis 'Filiformis', Brunswick, ME, 2013.
Photo by Sean Callahan
Thuja occidentalis 'Filiformis' foliage, fall 2013, Brunswick, ME.
Photo by Sean Callahan


Aleah Gaines

I live inThe Villages Florida and my local nursery sold this tree to me as suitable for zone 9b. I see on your website that it is only suitable to zone 8. How can I help keep my very expensive tree happy. I was afraid of over watering but it does brown out some during the summer.

Maxwell Cohn

hello Aleah ... this species is native to northern USA and Canada. It has evolved to expect COLD and SNOWY winters. I think it will limp along for you, but unfortunately, it will not thrive. USDA Zone 9b is semi-tropical. You're lucky to have many conifers available that will be very happy in your climate.

Pat Cowgill

I live very close to the beach in central California. We tend to get foggy summers and not a lot of hot days. Our thread needle is planted in sandy soil that is damp a little way down, due to being close to the ocean. Our plant was not in great shape when we found it tucked away in a nursery. After 2 years it seems a bit happier but not fully happy. It’s about 6 feet high and 4 feet wide. We get some wind from being by the coast. How much should I water my plant? Should the top be sprayed with water? What about feeding?

Maxwell Cohn

Hi Pat ... conifers generally only need supplemental water for the first 3 years after being planted, and only when the soil is dry to the touch 1.5 inches below the surface.

Fog does the same thing as spraying the foliage, so it's not necessary. Most conifers fail from rotted roots, and often the result of poor drainage or being planted too deep (is the root flare visible?)

Never fertilize a plant in the landscape unless a soil test indicates a deficiency.

Bill Hoffman

Thuja occidentalis 'Filiformis' and Thuja plicata 'Whipcord' are two different species. How does one tell them apart in the landscape without labels?

Maxwell Cohn

the plicata will have reddish bark on second-year branchlets. That's probably the only way unless you've handled millions of them.