# 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/

Try [black walnut](https://bluewhaletrees.com/tools/companions/index.html.md?species=black-walnut), [flowering dogwood](https://bluewhaletrees.com/tools/companions/index.html.md?species=flowering-dogwood) or [spicebush](https://bluewhaletrees.com/tools/companions/index.html.md?species=spicebush).

A native tree or shrub has companions, in the wild and in a yard. 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.

## Pick a tree or shrub to begin

Any of the 423 species we grow, or one of 45 other native trees and shrubs we do not grow. A large tree shows the shrubs and small trees that live in its shade; a shrub shows the trees to plant it under; everything shows its wild neighbors.

An example: black walnut, with the species its juglone rules out. Change any input for your own answer.

Black walnut's roots release juglone, which harms some plants. The Morton Arboretum lists rhododendron, linden, crabapple, yew, hackberry, blueberry, red chokeberry, red pine and larch as sensitive, so the 45 trees and shrubs of those kinds that we grow are left out here. The species it lists as tolerant are marked, and come first in the yard lists. The rest are on neither of its lists, which it calls incomplete.

### The 45 species left out

Alabama azalea, American basswood, American crabapple, Canada yew, Catawba rhododendron, Chapman's rhododendron, coastal azalea, common hackberry, creeping blueberry, Cumberland azalea, Darrow's blueberry, deerberry, dwarf hackberry, Elliott's blueberry, farkleberry, flame azalea, Florida flame azalea, Florida yew, hairy blueberry, hillside blueberry, Labrador tea, large cranberry, lingonberry, May white azalea, minnie-bush, Oconee azalea, Piedmont azalea, Piedmont rhododendron, pinkshell azalea, pinxterbloom azalea, plumleaf azalea, prairie crabapple, rabbiteye blueberry, red chokeberry, Red Hills azalea, red pine, rhodora, rosebay rhododendron, roseshell azalea, southern crabapple, sugarberry, swamp azalea, sweet azalea, tamarack and velvetleaf blueberry.

[What to plant under a black walnut](https://bluewhaletrees.com/articles/juglone-what-to-plant-under-a-black-walnut/index.html.md) tables the shrubs and small trees that two or more lists call tolerant and none calls sensitive.

![Black walnut (Juglans nigra) crown and compound leaves seen from below](https://bluewhaletrees.com/img/plants/black-walnut-160.jpg)

*Photo: R. A. Nonenmacher, CC BY-SA 4.0, cropped · [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Juglans_nigra_SCA-0322.jpg)*

## Under its canopy

Shrubs and small trees that take the shade a black walnut casts and like the same soil.

- [Wild Black Currant](https://bluewhaletrees.com/plants/wild-black-currant/index.html.md) (*Ribes americanum*): Shrub, Zones 3–7, 3–6 ft, Price on request. Shares floodplain forests and rich moist slopes in the wild. Hardy in zones 4 to 7 of the black walnut's 4 to 9. On Morton's tolerant list as “Currant (Ribes spp.)”.
- [American Hornbeam (Musclewood)](https://bluewhaletrees.com/plants/american-hornbeam/index.html.md) (*Carpinus caroliniana*): Small tree, Zones 3–9, 20–35 ft, Price on request. Shares floodplain forests in the wild. On Morton's tolerant list as “American hornbeam (Carpinus caroliniana)”.
- [Spicebush](https://bluewhaletrees.com/plants/spicebush/index.html.md) (*Lindera benzoin*): Shrub, Zones 4–9, 6–12 ft, Price on request. Shares floodplain forests in the wild. On Morton's tolerant list as “Spicebush (Lindera benzoin)”.
- [Wild Hydrangea](https://bluewhaletrees.com/plants/wild-hydrangea/index.html.md) (*Hydrangea arborescens*): Shrub, Zones 3–9, 3–6 ft, Price on request. Shares rich moist slopes in the wild. On Morton's tolerant list as “Wild hydrangea (Hydrangea arborescens)”.
- [Pawpaw](https://bluewhaletrees.com/plants/pawpaw/index.html.md) (*Asimina triloba*): Small tree, Zones 5–9, 15–30 ft, Price on request. Shares floodplain forests in the wild. Hardy in zones 5 to 9 of the black walnut's 4 to 9. On Morton's tolerant list as “Pawpaw (Asimina triloba)”.
- [Witch Hazel](https://bluewhaletrees.com/plants/witch-hazel/index.html.md) (*Hamamelis virginiana*): Shrub, Zones 3–8, 12–20 ft, Price on request. Shares rich moist slopes in the wild. Hardy in zones 4 to 8 of the black walnut's 4 to 9. On Morton's tolerant list as “Witch-hazel (Hamamelis spp.)”.

## Beside it

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

- [Bitternut Hickory](https://bluewhaletrees.com/plants/bitternut-hickory/index.html.md) (*Carya cordiformis*): Large tree, Zones 4–9, 50–80 ft, Price on request. Shares floodplain forests and rich moist slopes in the wild. On Morton's tolerant list as “Hickory (Carya spp.)”.
- [American Beech](https://bluewhaletrees.com/plants/american-beech/index.html.md) (*Fagus grandifolia*): Large tree, Zones 3–9, 50–80 ft, Price on request. Shares floodplain forests and rich moist slopes in the wild. On Morton's tolerant list as “American beech (Fagus grandifolia)”.
- [Yellow Buckeye](https://bluewhaletrees.com/plants/yellow-buckeye/index.html.md) (*Aesculus flava*): Large tree, Zones 3–8, 50–75 ft, Price on request. Shares floodplain forests and rich moist slopes in the wild. Hardy in zones 4 to 8 of the black walnut's 4 to 9. On Morton's tolerant list as “Yellow buckeye (Aesculus octandra)”.
- [Southern Shagbark Hickory](https://bluewhaletrees.com/plants/southern-shagbark-hickory/index.html.md) (*Carya carolinae-septentrionalis*): Large tree, Zones 5–8, 70–125 ft, Price on request. Shares floodplain forests and rich moist slopes in the wild. Hardy in zones 5 to 8 of the black walnut's 4 to 9. On Morton's tolerant list as “Hickory (Carya spp.)”.
- [White Oak](https://bluewhaletrees.com/plants/white-oak/index.html.md) (*Quercus alba*): Large tree, Zones 3–9, 50–80 ft, Price on request. Shares rich moist slopes in the wild. On Morton's tolerant list as “White oak (Quercus alba)”.
- [Shagbark Hickory](https://bluewhaletrees.com/plants/shagbark-hickory/index.html.md) (*Carya ovata*): Large tree, Zones 4–9, 60–90 ft, Price on request. Shares rich moist slopes in the wild. On Morton's tolerant list as “Hickory (Carya spp.)”.

## [Black Walnut](https://bluewhaletrees.com/plants/black-walnut/index.html.md) grows in floodplain forests and rich moist slopes

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

- [Red Mulberry](https://bluewhaletrees.com/plants/red-mulberry/index.html.md) (*Morus rubra*): Medium tree, 35–50 ft
- [Slippery Elm](https://bluewhaletrees.com/plants/slippery-elm/index.html.md) (*Ulmus rubra*): Medium tree, 40–70 ft · on Morton's tolerant list
- [Eastern Wahoo](https://bluewhaletrees.com/plants/eastern-wahoo/index.html.md) (*Euonymus atropurpureus*): Shrub, 6–20 ft
- [Devil's Walking Stick](https://bluewhaletrees.com/plants/devils-walking-stick/index.html.md) (*Aralia spinosa*): Small tree, 10–20 ft · on Morton's tolerant list
- [Butternut](https://bluewhaletrees.com/plants/butternut/index.html.md) (*Juglans cinerea*): Medium tree, 40–60 ft
- [Black Maple](https://bluewhaletrees.com/plants/black-maple/index.html.md) (*Acer nigrum*): Large tree, 60–75 ft
- [Kentucky Coffeetree](https://bluewhaletrees.com/plants/kentucky-coffeetree/index.html.md) (*Gymnocladus dioicus*): Large tree, 60–80 ft
- [American Holly, select line](https://bluewhaletrees.com/plants/american-holly/index.html.md) (*Ilex opaca*): Medium tree, 20–50 ft

How far apart: the [planting-distance tool](https://bluewhaletrees.com/tools/distance/index.html.md?species=black-walnut&near=tree) gives the gap between Black Walnut and any tree you name as the next one, by their pages' spacing or half of each crown, added.

- [When these flower and fruit](https://bluewhaletrees.com/tools/calendar/index.html.md?plants=black-walnut,wild-black-currant,american-hornbeam,spicebush,wild-hydrangea,pawpaw,witch-hazel,bitternut-hickory,american-beech,yellow-buckeye,southern-shagbark-hickory,white-oak,shagbark-hickory), 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.

## 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.
- **How far apart.** Each yard card links the planting-distance tool with both trees named. The tool gives the gap between them: each one's own spacing from its page, or half of each crown added, unless a page gives a larger distance from other trees. The wild list links the same tool with the chosen tree set, for any next tree you name.
- **Your zone.** With a zone chosen, the yard lists keep only species rated hardy in it.
- **Black walnut.** The 45 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 28 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 or shrub we do not grow.** The 45 common natives under their own group in the menu take the same tests, with their ground, zones, sun, soil and states of native range from their sources (Silvics of North America, the USDA PLANTS Database, the Woody Plant Seed Manual, the Fire Effects Information System and extension and botanical garden pages). The answer says so, links the species' own page, and offers the sign-up for the companions only.

## Common questions

### What can I plant under a black walnut tree?

Under a black walnut, the tool puts first the species on the Morton Arboretum's tolerant lists, such as [pawpaw](https://bluewhaletrees.com/plants/pawpaw/index.html.md), [spicebush](https://bluewhaletrees.com/plants/spicebush/index.html.md) and [flowering dogwood](https://bluewhaletrees.com/plants/flowering-dogwood/index.html.md). It leaves out those Morton lists as sensitive to the walnut's juglone, and Morton warns that any such list is incomplete.

### What should you not plant near a black walnut?

Of the trees and shrubs we grow, the Morton Arboretum lists crabapples, hackberries, lindens, rhododendrons, blueberries, larch, yew and red chokeberry as sensitive to black walnut's juglone. Azaleas count among the rhododendrons, and the tool keeps all of them out of a walnut's answer.

### What can I plant under a big tree?

Under a large tree, the tool lists up to six shrubs and small trees that take part shade or shade, and species of the forest understory rank higher. Our article on [what to plant under a big tree](https://bluewhaletrees.com/articles/what-to-plant-under-a-big-tree/index.html.md) covers planting without hurting the tree.

### Which native trees and shrubs grow together in the wild?

The tool lists up to eight natives that share a natural community with your species and grow wild in one of its states, by the USDA PLANTS Database. The communities are our own tags, and sharing one does not mean two species always grow side by side.

### Can eastern red cedar be planted near crabapples?

The University of Minnesota Extension says not to plant [eastern red cedar](https://bluewhaletrees.com/plants/eastern-red-cedar/index.html.md) within a few hundred yards of crabapples, hawthorns, serviceberries, chokeberries or mountain ash, since cedar-apple and related rusts live on both. The tool keeps them out of each other's answers.

The communities are our own tags. Every species we grow, with its communities, is in the [habitats table, A to Z](https://bluewhaletrees.com/articles/plant-habitats/index.html.md). The states of native range are the USDA PLANTS Database's records, read between 2026-09-23 and 2026-10-28 (2026-10-13 for the common natives we do not grow), 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, or its record for a common native we do not grow. 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 species 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.

The address carries the companion species tool's inputs, so a link opens it filled in, and Copy link on a result writes one: species (a plant's slug, the last part of its page's address, such as white-oak), zone (a whole number from 2 to 10, to keep the companions to it), sort (featured, name, price-asc, price-desc, height, hardy or fast). For example, [/tools/companions/?species=white-oak&zone=6](https://bluewhaletrees.com/tools/companions/index.html.md?species=white-oak&zone=6).