Updated: Mar 11
It is easy to dismiss some of the more Plane Jane plants of the ornamental landscape, but for landscape architects, they can play key roles in garden designs. Case in point, the rather unremarkable Pittosporum tenuifolium, with its elegant glossy medium green coloring and dense foliage. Lined up in the landscape, they are perfect for spatial delineation.
A popular design element is the outdoor room; the very idea prompts notions of walls separating spaces, however such walls are not always made from architectural materials like brick or wood. Often, designers will specify shrubbery to act as walls, but this means that plants should be reliable performers to maintain separation of sequential spaces. P. tenuifolium is one such plant.
Evergreen, P. tenuifolium will become a small tree if left on its own, but designers will use it as a formal hedge, offering an opportunity to define spaces, creating privacy screens, or providing a clean background for feature plants, sculpture, or site furnishings. Their lighter coloring is a little more challenging to work with, so foreground materials should offer a striking contrast so not to blend into the background. That's why other species, such as Taxus baccata or Ligustrum japonicum 'Texanum' tend to be more desirable for their dark green that helps to "pop" colors in their foreground. If P. tenuifolium's color works with the design, then as a hedge, it lends itself to hedging due to its smaller leaves.
Students hear me discuss appropriate plant selections for hedges all the time. The smaller the leaves, the more the plant lends itself to formal hedges, as in the species discussed here. Large-leaf species pruned into formal shapes can create an unsightly mass of butchered leaves, hacked away from mechanical hedging devices. So, for formal hedges and topiaries, stick to small-leaf varieties.
The first hedge I ever planted was at my childhood home was P. tenuifolium, and its still there some forty years later. The current owners maintain it at about five feet high, just as we did when we lived there. A funny thing happened after our hedge grew in; neighbors up and down the street started planting hedges, too, creating a lush public landscape on a small residential street. I planted it to change the view from our home's windows...instead of asphaltic pavement and cars, the view turned inward creating a courtyard like garden...an outdoor room. This was before I knew what landscape architecture was as a profession or academic study, but clearly I had the mindset.
'Abbotsbury Gold': Several sources discuss yellow-gold-green foliage, but photos do not depict it well. Approximate growth 8'-10' tall and wide.
'Irene Paterson': Variegated leaves starting white but becoming mottled white with some dark green. Smaller size to 5' tall and wide.
'Marjorie Shannon': Light green leaves with white margin, only reaching 8'-10' tall and wide.
'Silver Magic': Variegated medium green with irregular white marking up to 15'-20' tall by 8'-10' wide.
'Silver Sheen': Small, silver-green leaves, open growth form can be dense with pruning. Height 12'-16' by 6'-8' wide.
'Wrinkled Blue': Wavy light blue-green leaves contrasting with nearly black stems reaching 12' tall by 6' wide.
Landscape architect Jeff Wortham once again provides a great summary of Pittosporum tenuifolium including mention of two cultivars.
Botanical Name: Pittosporum tenuifolium
Pittosporum: Greek, pitta, for the pitch-like sticky substance on the spora, or seed.
Tenuifolium: Having slender leaves
Common Name: Kohuhu; tawhiwhi; tarata pittosporum
Family Name: Pittosporaceae
Origin: New Zealand
Garden Themes: Courtyard/patio, Mediterranean/drought, urban/suburban residential, commercial, public spaces
Uses: Large informal or formal hedge, shrub border, multi-trunk tree, screen/privacy, topiary, windbreak (dislikes cold winds)
Type: Evergreen shrub to small tree
Form: Round, upright
Size: 15'-25' tall by 10'-15' wide (cultivars vary)
Outstanding Feature(s): Foliage
Stem: Dark gray to black
Color: Medium green (cultivars vary)
Surface: Glabrous, glossy
Flower: Summer. Small, five-petaled, slightly fragrant, deep burgundy-black rendering them mostly inconspicuous.
Fruit: Summer to autumn. Small, woody capsule opens to reveal dark fruit with sticky residue.
cultural requirements, tolerances & problems
Sunset Zones: 9, 14-17, 19-24
USDA Zones: 9-10
Light: Full sun to light shade
WUCOLS SF Bay Area Hydro Zone: Moderate
Texture: Sand, loam
Moisture Retention: Well-drained
pH: Slightly acidic to slightly alkaline
Tolerances: Drought, salt spray, deer
Branch Strength: Medium, flexible
Insects: Scale, aphids
Disease: Sooty mold, anthracnose
citations & attributions
Bayton, R. (2019). The Royal Horticultural Society's the Gardener's Botanical: An Encyclopedia of Latin Plant Names. London: Mitchell Beazley.
Breen, P. "Landscape Plants." College of Agricultural Sciences, Department of Horticulture, Oregon State University, Corvalis. Accessed on January 1, 2022 from https://landscapeplants.oregonstate.edu/plants/pittosporum-tenuifolium-marjorie-channon.
Norris Brenzel, K. (Ed.). (2012). The New Sunset Western Garden Book. New York: Time Home Entertainment, Inc.
SelecTree. UFEI. "Pittosporum tenuifolium Tree Record." 1995-2021. Cal Poly State University, San Luis Obispo. Accessed on January 1, 2022, from https://selectree.calpoly.edu/tree-detail/1095.
Water Use Classification of Landscape Species. "WUCOLS IV Plant List." University of California, Division of Agriculture and Natural Resources, Davis. Accessed on January 1, 2022, from https://ucanr.edu/sites/WUCOLS/files/183488.pdf.
Form: "Pittosporum tenuifolium 'Abbotsbury Gold'" by Leonora (Ellie) Enking is licensed under Creative Comments - ShareAlike 2.0 Generic (CC BY-SA 2.0).
All other photos by TELCS.