# Red Alder (Alnus rubra)

> Red alder, Alnus rubra: a large tree of 40 to 98 feet where planted, for zones 5 to 8, when it flowers and fruits, and the natives we grow for the same ground.

Blue Whale Trees, a native tree nursery in the United States. Web version: https://bluewhaletrees.com/species/red-alder/

![A dense stand of young red alders with pale, lichen-mottled trunks beside a paved trail in late winter](https://bluewhaletrees.com/img/species/red-alder-1000.jpg?v=03bdb7ab "Young red alders along the Banks-Vernonia trail at Buxton, Oregon, on March 28, 2026. Its maximum age is about 100 years.")
*Photo: Samsung.55.3636, [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0) ([source](https://commons.wikimedia.org/wiki/File%3AYoung_Alnus_rubra_20260328.jpg))*

Large tree, 40 to 98 feet where planted, zones 5 to 8; full sun; dry, average or wet ground.

We do not grow red alder, and it is not in our shop. This page gathers what our tools say about it and the natives we grow for the same ground.

## At a glance

| Fact | Red Alder |
| --- | --- |
| Other names | Oregon alder, western alder, Pacific Coast alder |
| Form | Large tree |
| Height, feet | 40 to 98 where planted; up to 130 in its native stands |
| Spread, feet | Up to 50 |
| Zones | 5 to 8 |
| Sun | Full sun |
| Soil moisture | Dry, average or wet ground |
| Growth | Fast |
| Leaves | Deciduous |
| Traits | Wildlife value, hedge or screen, nitrogen fixing, erosion control |
| Flowers | February to May |
| Fruit | Cones, August to February |
| First crop | 3 to 4 years (most trees in a stand 6 to 8) |
| Pollination | One bears; a second improves the crop. Male and female catkins grow on the same tree. Most seed comes from crossing between trees, though a lone tree sets some from its own pollen. |
| Lifespan | Lives up to 100 years. |
| Planting season | Spring. The NRCS plant guide sets seedlings out in summer if they are big enough, otherwise the following spring. |
| Black walnut | Not named on the Morton Arboretum's lists |
| Ground | Floodplain forests, stream banks, the coast, swamps and wet flats |
| Native in | 6 states |

Red alder is native in 6 states: [Alaska](https://bluewhaletrees.com/tools/native/index.html.md?state=AK), [California](https://bluewhaletrees.com/tools/native/index.html.md?state=CA), [Idaho](https://bluewhaletrees.com/tools/native/index.html.md?state=ID), [Montana](https://bluewhaletrees.com/tools/native/index.html.md?state=MT), [Oregon](https://bluewhaletrees.com/tools/native/index.html.md?state=OR) and [Washington](https://bluewhaletrees.com/tools/native/index.html.md?state=WA). The states are the USDA PLANTS Database's records, with the native range read from Silvics of North America, the Fire Effects Information System, the NRCS plant guide and NC State Extension.

## What our tools say

- [How fast it grows and how big it gets, by site](https://bluewhaletrees.com/tools/growth/index.html.md?species=red-alder): the growth estimator
- [Whether it suits your zone, sun and soil](https://bluewhaletrees.com/tools/site-check/index.html.md?species=red-alder): the planting-site check
- [How far from a house, wires and a septic field](https://bluewhaletrees.com/tools/distance/index.html.md?species=red-alder&near=house,septic,pavement,wires,boundary,tree): the planting-distance tool
- [What grows with it in the wild and in a yard](https://bluewhaletrees.com/tools/companions/index.html.md?species=red-alder): the companion species tool
- [When to plant it where you live](https://bluewhaletrees.com/tools/planting-window/index.html.md?species=red-alder): the planting-window tool
- [When it flowers and fruits, month by month](https://bluewhaletrees.com/tools/calendar/index.html.md?plants=red-alder): the bloom and fruit calendar
- [How to sow its seed, with dates for your place](https://bluewhaletrees.com/tools/sowing/index.html.md?species=red-alder): the seed sowing planner
- [How many to plant for a crop of seed](https://bluewhaletrees.com/tools/pollination/index.html.md?plants=red-alder:2): the pollination planner
- [Whether one you have can be moved, and what the move takes](https://bluewhaletrees.com/tools/transplant/index.html.md?species=red-alder): the transplant planner
- [How old one is, from its trunk](https://bluewhaletrees.com/tools/tree-age/index.html.md?species=red-alder): the tree age calculator
- [How a big one scores against the champion trees](https://bluewhaletrees.com/tools/big-tree/index.html.md?species=red-alder): the big-tree measurer

## For the same ground, we grow

- [American Elm](https://bluewhaletrees.com/plants/american-elm/index.html.md) (*Ulmus americana*): large tree, 60 to 80 feet, zones 2 to 9. Shares floodplain forests, stream banks, swamps and wet flats in the wild.
- [Balsam Poplar](https://bluewhaletrees.com/plants/balsam-poplar/index.html.md) (*Populus balsamifera*): large tree, 30 to 100 feet, zones 2 to 5. Shares floodplain forests, stream banks, swamps and wet flats in the wild.
- [Peachleaf Willow](https://bluewhaletrees.com/plants/peachleaf-willow/index.html.md) (*Salix amygdaloides*): medium tree, 35 to 60 feet, zones 2 to 8. Shares floodplain forests, stream banks, swamps and wet flats in the wild.
- [Tamarack](https://bluewhaletrees.com/plants/tamarack/index.html.md) (*Larix laricina*): large tree, 50 to 75 feet, zones 2 to 6. Shares stream banks, swamps and wet flats in the wild.
- [Bur Oak](https://bluewhaletrees.com/plants/bur-oak/index.html.md) (*Quercus macrocarpa*): large tree, 60 to 80 feet, zones 3 to 9. Shares floodplain forests in the wild.
- [American Plum](https://bluewhaletrees.com/plants/american-plum/index.html.md) (*Prunus americana*): small tree, 15 to 25 feet, zones 3 to 8. Shares stream banks in the wild.
- [Every companion of red alder in the companion species tool](https://bluewhaletrees.com/tools/companions/index.html.md?species=red-alder)

## Read from

Its figures come from Silvics of North America, the Forest Service's Fire Effects Information System, the Woody Plant Seed Manual, the USDA PLANTS Database, Oregon State University's Landscape Plants, Cal Poly's SelecTree, NC State Extension, the Wildflower Center and Calscape.