Permaculture Plants: Pea Trees and Pea Shrubs

Siberian Pea Tree/Shrub (Caragana arborescens)

Description:
Known as Pea Shrubs or Trees (if they get large enough), the Caragana species are in the Legume Family, and they really do produce edible pods and peas. The Pea Shrubs are on my list of Permaculture super-plants! They are edible, fix-nitrogen, attract beneficial insects, can be used as a pioneer plant, a windbreak, and a hedge, are used to stabilize erosion-prone soil, can feed livestock, and are pretty with fragrant flowers. What more could you ask for in one plant?

Caragana species

History:
Native and widespread through Asia and eastern Europe, this plant has been used by native peoples for its edible pods and seeds, fiber from the bark, and dye from its leaves. It has been spread around the world first for its pods and seeds by settlers and in more modern times for its ornamental properties. It is also very recently begun to be used as a windbreak, erosion control, and degraded land reclamation plant.

Trivia:

• Pea Shrubs are considered invasive species in many locations in the United States… this just tells me there is a void which this plant is filling.
• Pea Shrubs can withstand -40 F (-40 C) temperatures – perfect for very cold locations!

There are many uses for the Pea Shrubs – seen here is Siberian Pea Tree/Shrub (Caragana arborescens) being used as a windbreak/hedge.

Primary Uses:

• Ornamental Plant – this has been one of its primary uses around the world due to its small fragrant flowers and attractive leaves
• Edible Pods – Young pods are eaten raw or cooked in Summer.
• Edible Seeds – Historically, Pea Shrubs were used for food much more than they are now. The pods form 3-4 “peas” each, and these peas can be eaten raw or cooked when young. The seeds may also be dried and then used like dried peas – soaked overnight and then cooked before eating. Some people still enjoy eating from this plant, but others find the taste bland and the small, low-seeding pods bothersome to open and not worth the trouble. The tree does produce a lot of pods though, so it may have potential as a future food source. I have yet to try pods or peas from this plant… I’ll let you know when I do
• Edible Flowers – reportedly can be used as a salad garnish

Secondary Uses:

• Nitrogen Fixer – this plant creates its own nitrogen through a symbiotic relationship with microorganisms (bacteria) in its roots. It typically produces an excess of nitrogen that can be used by neighboring plants. This is a leguminous plant; Clover, Cowpea, Lupine, Soybean inoculation groups.
• General insect (especially bees) nectar plant
• Pioneer Plant – helps reestablish overused or damaged land
• Windbreak Plant – fast growing, but not very tall
• Hedge Plant – the thorns on this plant will likely make it a worthwhile food-producing, living fence for livestock
• Wildlife Food – many animals will eat the seeds and hummingbirds enjoy the nectar
• Wildlife Shelter – mainly birds
• Lacewings prefer to lay eggs on Caranga species
• Parasitic Wasps prefer to rest and hide on Caranga species
• Erosion Control Species – the extensive root system helps stabilize soils prone to erosion
• Fodder Crop – chickens particularly enjoy this plant’s pods and seed, but there is also research supporting its use as fodder for sheep, goats, cattle, deer, reindeer, and camels!
• Fiber Plant – a fiber from the bark can be used to make cordage
• Dye Plant – a blue dye can be made from the leaves

Yield: No reliable information can be found, but these plant yield high quantities of pods each year.
Harvesting:  Summer – pods can be harvested when very small (just over an inch). Autumn – if the pods are older but still green, they the peas can be eaten raw or cooked. If the pods have turned brown, pick them before they split and harvest the dried peas.
Storage: Use pods and young peas within a few days. The dried peas will keep for years if kept in a dry location.

The pioneering Caragana species will help rebuild poor soils.
Russian Pea Shrub (Caragana frutex).

USDA Hardiness Zone:

• Siberian Pea Tree/Shrub (Caragana arborescens): Zone 2-7
• Caragana boisii (Caragana boisii): Zone 2
• Caragana brevispina (Caragana brevispina): Zone 6
• Caragana decorticans (Caragana decorticans): Zone 6
• Russian Pea Shrub (Caragana frutex): Zone 2-7
• Pygmy Pea Shrub (Caragana pygmeae): Zone 2-7

AHS Heat Zone:

• Siberian Pea Tree/Shrub (Caragana arborescens): Zone 8-1

Chill Requirement: No reliable information is available, but it is likely considering its origination location.

Plant Type: Medium to Very Large Shrub
Leaf Type: Deciduous
Forest Garden Use: Canopy Layer
Cultivars/Varieties: There are a number of varieties of Caragana arborescens available, but these were all developed for flowers, not for other beneficial characteristics. Other than that, almost no development has been undertaken.

Pollination: Self-fertile. Bee pollinated.
Flowering: Spring

Years to Begin Fruiting: 3-5 years
Life Span: Up to 50+ years

There are a variety of sizes in the Caragana genus.
Here is the medium-sized Russian Pea Shrub (Caragana frutex).

And the small Pygmy Pea Shrub (Caragana pygmeae)

Size:

• Siberian Pea Tree/Shrub (Caragana arborescens): 8-20 feet (2.4-6 meters) tall and 12-18 feet(3.5-5.5 meters) wide
• Caragana boisii (Caragana boisii): 8-20 feet (2.4-6 meters) tall and 13 feet(4 meters) wide
• Caragana brevispina (Caragana brevispina): 8 (2.4 meters) tall
• Caragana decorticans (Caragana decorticans): 18 feet (5.5 meters) tall
• Russian Pea Shrub (Caragana frutex): 6-10 feet (1.8-3 meters) tall and wide
• Pygmy Pea Shrub (Caragana pygmeae): 4 feet (1.2 meters) tall and wide

Roots: Fairly deep, but very extensive root system (used for erosion control)
Growth Rate: Medium to Fast

Fragrant flowers are just the icing on the cake of this multi-use “wonder-shrub”!

Light: Prefers full sun
Shade: Does not tolerate shade
Moisture: Dry to medium-moisture soils. Can tolerate failry dry conditions once established.
pH: 5.1-8.5 (tolerates a wide range of soil conditions)

Special Considerations for Growing: None.

Propagation:
Typically from seed. Soak for 24 hrs first. If the seed has not swollen, then scarify and soak again for 12 hrs. Typically germinates in 2-3 weeks. Not dormant. Can be propagated from cuttings and layering as well.

Maintenance: Minimal once established.

Concerns:

• Most species have thorns which can be annoying to problematic depending on where they are planted and how they are used.
• In some areas, the Caragana species are considered invasive; however, this appears to be more of a case in disturbed areas… which is why this is considered a great pioneer species. If the land was not mismanaged in the first place, and repeatedly disturbed, then there would be no place for pioneer species like this, and there would be no “invasive” label to this plant.