Alders are sometimes hard to find in local garden centers and tree nurseries around the country. It can be a valuable asset in a yard with landscaping problems such as wet soil or just plain lousy soil. Just like peas in the vegetable garden, Alders are legumes which means their roots fix atmospheric nitrogen, consequently it makes much of its own fertilizer. Most species are fast growers and when grown as a multi-stemmed plant, they can create a sound barrier screen in just a few years.
While there are some native Alders in the United States, the two best species come from Europe. European Alder (Alnus glutinosa) is probably the most commonly grown Alder in American home landscapes. However, there is a significant vocal minority who say the Italian Alder (Alnus cordata) offers some terrific landscape values overlooked by growers up to this point.
Species |
Size |
Zones |
European Alder (Alnus glutinosa) |
At 20 years the height is 30’ with a spread of 15’. Mature height is 40 to 50’ with a spread of 20 to 40’ Growth rate is fast when young, slowing to moderate 12 to 15 inches per year |
Zones 3A through 7B, Full sun and partial shade, any soils. |
Italian Alder (Alnus cordata)
|
Mature height 35 to 40’ |
Zones 5 through 8A |
White Alder (Alnus rhombifolia) |
Mature height 50 to 75’ with a spread of 30 to 40’ |
Zones 8A through 11 |
Japanese Alder (Alnus japonica) |
Mature height 12 to 25’ with a spread of 8 to 12’ |
Zones 6 through 9 |