# Companion species

> Pick one native tree or shrub and see the species that share its ground in the wild, live under its canopy, or want the same sun, soil and climate in a yard.

Blue Whale Trees, a native tree nursery in the United States. Web version: https://bluewhaletrees.com/tools/companions/?species=eastern-red-cedar

Pick one native tree or shrub and see what grows with it. The matches come in three groups. Some species share its ground in the wild, and others live under its canopy or are the trees it can be planted beneath. The rest suit the same yard because they want the same sun, soil and climate. Every match is explained on the page, so you can see why a species is listed.

Eastern red cedar carries the cedar-apple, hawthorn, quince and juniper broom rusts over winter. They spend the rest of their lives on crabapples, hawthorns, serviceberries, chokeberries and mountain ash. The University of Minnesota Extension says not to plant it within a few hundred yards of them, so the 25 trees and shrubs of those kinds that we grow are left out here.

### The 25 species left out

Allegheny serviceberry, American crabapple, American mountain ash, Bartram's serviceberry, black chokeberry, blueberry hawthorn, cockspur hawthorn, downy hawthorn, downy serviceberry, green hawthorn, Harbison's hawthorn, littlehip hawthorn, mayhaw, Nantucket serviceberry, parsley hawthorn, pear hawthorn, prairie crabapple, red chokeberry, roundleaf serviceberry, shadblow serviceberry, southern crabapple, three-flower hawthorn, Washington hawthorn, weeping hawthorn and western mayhaw.

## Eastern Red Cedar grows in rocky ground, dry uplands, old fields and edges

These natives share that ground, so they will look right together and want the same care.

- [Common Hackberry](https://bluewhaletrees.com/plants/common-hackberry/index.html.md) (*Celtis occidentalis*): Large tree, 40–60 ft
- [New Jersey Tea](https://bluewhaletrees.com/plants/new-jersey-tea/index.html.md) (*Ceanothus americanus*): Shrub, 2–3 ft
- [Common Prickly Ash (Toothache Tree)](https://bluewhaletrees.com/plants/common-prickly-ash/index.html.md) (*Zanthoxylum americanum*): Shrub, 10–20 ft
- [Fragrant Sumac](https://bluewhaletrees.com/plants/fragrant-sumac/index.html.md) (*Rhus aromatica*): Shrub, 2–6 ft
- [Hillside Blueberry](https://bluewhaletrees.com/plants/hillside-blueberry/index.html.md) (*Vaccinium pallidum*): Shrub, 1–3 ft
- [Staghorn Sumac](https://bluewhaletrees.com/plants/staghorn-sumac/index.html.md) (*Rhus typhina*): Shrub, 15–25 ft
- [Dwarf Hackberry](https://bluewhaletrees.com/plants/dwarf-hackberry/index.html.md) (*Celtis tenuifolia*): Small tree, 15–30 ft
- [Prairie Redroot](https://bluewhaletrees.com/plants/prairie-redroot/index.html.md) (*Ceanothus herbaceus*): Shrub, 2–3 ft

## Under its canopy

Shrubs that take the shade an eastern red cedar casts and like the same soil.

- [Downy Arrowwood](https://bluewhaletrees.com/plants/downy-arrowwood/index.html.md) (*Viburnum rafinesqueanum*): Shrub, Zones 3–8, 3–10 ft, Price on request. Shares rocky ground, dry uplands, old fields and edges in the wild. Hardy in zones 3 to 8 of the eastern red cedar's 2 to 9.
- [Gray Dogwood](https://bluewhaletrees.com/plants/gray-dogwood/index.html.md) (*Cornus racemosa*): Shrub, Zones 4–8, 4–10 ft, Price on request. Shares rocky ground, dry uplands, old fields and edges in the wild. Hardy in zones 4 to 8 of the eastern red cedar's 2 to 9.
- [Blackhaw Viburnum](https://bluewhaletrees.com/plants/blackhaw/index.html.md) (*Viburnum prunifolium*): Shrub, Zones 3–9, 12–15 ft, Price on request. Shares dry uplands, old fields and edges in the wild. Hardy in zones 3 to 9 of the eastern red cedar's 2 to 9.
- [Mapleleaf Viburnum](https://bluewhaletrees.com/plants/mapleleaf-viburnum/index.html.md) (*Viburnum acerifolium*): Shrub, Zones 3–8, 3–6 ft, Price on request. Shares rocky ground and dry uplands in the wild. Hardy in zones 3 to 8 of the eastern red cedar's 2 to 9.
- [Carolina Buckthorn](https://bluewhaletrees.com/plants/carolina-buckthorn/index.html.md) (*Frangula caroliniana*): Shrub, Zones 5–9, 10–20 ft, Price on request. Shares rocky ground and dry uplands in the wild. Hardy in zones 5 to 9 of the eastern red cedar's 2 to 9.
- [Roughleaf Dogwood](https://bluewhaletrees.com/plants/roughleaf-dogwood/index.html.md) (*Cornus drummondii*): Shrub, Zones 5–8, 6–15 ft, Price on request. Shares rocky ground, dry uplands, old fields and edges in the wild. Hardy in zones 5 to 8 of the eastern red cedar's 2 to 9.

## Beside it

Plants that want the same sun and soil, for a bed, a hedge or a grove, with the same size class first.

- [Winged Elm](https://bluewhaletrees.com/plants/winged-elm/index.html.md) (*Ulmus alata*): Medium tree, Zones 6–9, 40–60 ft, Price on request. Shares rocky ground, dry uplands, old fields and edges in the wild. Hardy in zones 6 to 9 of the eastern red cedar's 2 to 9.
- [Hop Hornbeam](https://bluewhaletrees.com/plants/hop-hornbeam/index.html.md) (*Ostrya virginiana*): Medium tree, Zones 3–9, 25–40 ft, Price on request. Shares rocky ground and dry uplands in the wild. Hardy in zones 3 to 9 of the eastern red cedar's 2 to 9.
- [Sassafras](https://bluewhaletrees.com/plants/sassafras/index.html.md) (*Sassafras albidum*): Medium tree, Zones 4–9, 30–60 ft, Price on request. Shares dry uplands, old fields and edges in the wild. Hardy in zones 4 to 9 of the eastern red cedar's 2 to 9.
- [Chinquapin Oak](https://bluewhaletrees.com/plants/chinquapin-oak/index.html.md) (*Quercus muehlenbergii*): Medium tree, Zones 3–8, 40–60 ft, Price on request. Shares rocky ground and dry uplands in the wild. Hardy in zones 3 to 8 of the eastern red cedar's 2 to 9.
- [Post Oak](https://bluewhaletrees.com/plants/post-oak/index.html.md) (*Quercus stellata*): Medium tree, Zones 5–9, 35–50 ft, Price on request. Shares rocky ground and dry uplands in the wild. Hardy in zones 5 to 9 of the eastern red cedar's 2 to 9.
- [Shingle Oak](https://bluewhaletrees.com/plants/shingle-oak/index.html.md) (*Quercus imbricaria*): Medium tree, Zones 4–8, 40–60 ft, Price on request. Shares dry uplands, old fields and edges in the wild. Hardy in zones 4 to 8 of the eastern red cedar's 2 to 9.
- [When these flower and fruit](https://bluewhaletrees.com/tools/calendar/#plants=eastern-red-cedar,downy-arrowwood,gray-dogwood,blackhaw,mapleleaf-viburnum,carolina-buckthorn,roughleaf-dogwood,winged-elm,hop-hornbeam,sassafras,chinquapin-oak,post-oak,shingle-oak), in the bloom and fruit calendar.
- [What to plant under a big tree](https://bluewhaletrees.com/articles/what-to-plant-under-a-big-tree/index.html.md), and how to plant without harming its roots.
- [The habitat around a tree is part of the tree](https://bluewhaletrees.com/articles/habitat-around-a-tree/index.html.md): what keeps its roots alive.
- [Native hedges, screens and windbreaks](https://bluewhaletrees.com/articles/native-hedges-screens-and-windbreaks/index.html.md): which to use, and how far apart.

## Email me when Eastern Red Cedar or a companion is ready to order

For Eastern Red Cedar, Downy Arrowwood, Gray Dogwood, Blackhaw Viburnum, Mapleleaf Viburnum, Carolina Buckthorn, Roughleaf Dogwood, Winged Elm, Hop Hornbeam, Sassafras, Chinquapin Oak, Post Oak: one email per plant when it is priced or back in stock, and nothing else.

## How the matches are made

- **Natural communities.** Every species we grow is tagged with the communities it lives in: floodplain forests, swamps and wet flats, stream banks, rich moist slopes, dry uplands, sandy barrens, rocky ground, old fields and edges, the forest understory, the Appalachians and the coast.
- **In the wild.** Up to eight natives that share one of those communities with it and grow wild in one of its states. The most communities in common come first, then the native range most like its own. A species in a yard list is not repeated here.
- **Under its canopy, or trees to plant it under.** Up to six species at least two sizes apart, the smaller one taking part shade or shade: shrubs under a medium tree, shrubs and small trees under a large one.
- **Beside it.** Up to six that share a sun with it, the same size first.
- **The order of a yard list.** Every yard pick shares a zone, a soil and a state of native range with it. A shared community counts two points, and a shared sun or soil one. Under a canopy, a species of the forest understory counts two more, and one that takes full shade one more. Of equal scores, the one hardy in more of its zones comes first.
- **Your zone.** With a zone chosen, the yard lists keep only species rated hardy in it.
- **Black walnut.** The 37 species we grow that the Morton Arboretum lists as sensitive to its juglone are left out of its answer, and it is left out of theirs. Under a walnut, the species on Morton's tolerant lists come first and are marked.
- **Eastern red cedar.** The 25 crabapples, hawthorns, serviceberries, chokeberries and mountain ash we grow are left out of its answer, and it is left out of theirs: the cedar-apple, hawthorn, quince and juniper broom rusts live on both, and the University of Minnesota Extension says to keep them a few hundred yards apart.
- **A tree we do not grow.** The note under the menu names a relative we grow, in the words of its page.

The communities are our own tags. The states of native range are the USDA PLANTS Database's records, read on 2026-09-23, as the [native trees by state](https://bluewhaletrees.com/tools/native/index.html.md) tool reads them. Zones, sun and soil are each species' own page. The juglone lists are the Morton Arboretum's, read on 2026-10-05, which warns that "any list regarding this topic is incomplete and some of the information may be anecdotal." The rusts' hosts are the University of Minnesota Extension's, read on 2026-10-06. [What to plant under a big tree](https://bluewhaletrees.com/articles/what-to-plant-under-a-big-tree/index.html.md) and [the article on juglone](https://bluewhaletrees.com/articles/juglone-what-to-plant-under-a-black-walnut/index.html.md) cover the subject.

Sharing a habitat tag does not mean two plants always grow side by side, and a tag says nothing about how far apart to plant them. Use the [planting-site check](https://bluewhaletrees.com/tools/site-check/index.html.md) for the spot itself, and the [growth estimator](https://bluewhaletrees.com/tools/growth/index.html.md) for how much room each one will want in twenty years.