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Sacramento Valley Elderberry Field Assessment

Key takeaways

  • Blue elderberry seedlings yielded more and grew faster than American elderberry cultivars over the first two growing seasons.

  • Yields increase as hedgerows mature from 4 years to 8 years of age.

  • Un-irrigated mature blue elderberry shrubs were highly productive but yield was variable, possibly due to differences in genetics, spacing, water access, and other factors. 

  • Main blue elderberry bloom on second-year plants began in mid-April and ended by late July, although occasional flowers persisted through September.

  • Harvest window for blue elderberries was mid June to late September, with a peak in early August. Yield peak timing in young plants may differ from un-irrigated mature shrubs. 

  • Good weed management, proper land preparation, and frequent irrigation may increase growth and yield over the first two growing seasons.
Further reading

Complete Elderberry Field Assessment report (pdf). (Fyrie et al., 2020)

Native blue elderberry in hedgerows bridges revenue and conservation goals (Brodt, et al. 2024)

Due to the conservation status of the Valley Elderberry Longhorn Beetle (VELB) and federal restrictions on certain pruning practices and removal of blue elderberry plants within the known range of the VELB, please read: Valley Elderberry Longhorn Beetle – What California Growers Need to Know

This field demonstration focused on comparing blue elderberry and American elderberry for fruit production in Sacramento Valley hedgerows.  Blue elderberry is native to the west coast and is currently most commonly planted for habitat, while American elderberry is native east of the Rockies and is more prominent in commercial fruit and flower production.  

Goals

  • Explore best establishment and management practices for elderberry in California hedgerows

  • Assess potential mature yield of un-irrigated blue elderberry

  • Assess harvest window and peak season for blue elderberry harvest

  • Compare American elderberry to blue elderberry over first two growing seasons

Early growth and yield

We planted blue and American elderberries on three organic Yolo/Solano farms, then tracked their growth and yield for two growing seasons (Table 1 and Figure 1). 

Table 1. Blue elderberry and American elderberry growth comparison

Blue elderberry and American elderberry growth comparison

harvest window graph

Elderberry row at farm A

Farm A

Elderberry row at farm B

Farm B

Elderberry row at farm C

Farm C

 

Blue elderberries were planted in 1,000-foot hedgerows in three different designs and pre-planting ground preparations: multiple California native species in adjacent rows with deep tillage, high-density elderberry-only hedgerow with shallow tillage, and low-density elderberry interspersed in existing border vegetation with no tillage (Table 2). We tracked the yield for blue elderberry hedgerows for a third season at all three farms and for five seasons at Farm A (Table 3).

Table 2. Field site planting design, preparation and early management.

Table describing planting design for hedgerows 1, 2 and 3.

 

Table 3. Average annual berry yields for blue elderberry in 1, 000-foot hedgerows (pounds destemmed berries).

Table showing average annual berry yields for blue elderberry in 1,000-foot hedgerows (pounds destemmed berries)

During the fourth season, when measurements were taken only in Hedgerow 1, the cessation of irrigation corresponded with a severe drought, causing yields to decline precipitously. However, yields bounced back to year 2 levels in the fifth season, despite continuing drought and absence of irrigation, demonstrating the resilience of blue elderberry. 

Strategies that may increase early growth and yield

Early growth is key:  Increasing growth rate in year one appears to increase yields in year two.  Choose management strategies that encourage wide, highly-branching growth with many basal shoots for maximum early per-tree yield.  

Timing and tillage:  Regardless of tillage strategy, fall is the best time to plant perennials in California, when soil softened by winter rains is easier for young roots to explore. For spring plantings, tillage may be especially important to help young roots to develop more quickly. Deep tillage may help deep and extensive root systems develop sooner if the planting site is compacted. 

Irrigation:  Weekly irrigation over the first two growing seasons may result in more extensive growth and higher early yield than less frequent irrigation, even with the same total quantity of water over the season. 

Mulch and weed control:  Using mulch is recommended for maintaining moisture, cooling and protecting soil, and controlling weeds.  Weeds should be carefully controlled; special care should be taken during the first winter rainy season when young plants are dormant. 

Tree protection tubes:  If using tree protection tubes to prevent damage to young plants, remove them relatively early to encourage basal sprouting for maximum per-plant yield. Tubes can be removed as soon as the plants are growing vigorously, especially if leaves are pressing against the sides of the tubes. If tubes are left on, some early yield may be sacrificed as basal sprouts can be stunted or killed from extreme heat inside the tube. 

Vegetative propagation and cultivar development: Since there is a significant variation in yield from one year to the next, as well as between individual plants, refining vegetative propagation techniques and using them to establish defined cultivars could improve uniformity and reliability of yields.

Mature plant yields

We harvested the ripe berries from nine established shrubs of known ages in un-irrigated Yolo/Solano county hedgerows weekly for two summer harvest seasons (2018, 2019). 

Table 4. Mature unirrigated blue elderberry yield results

Table of mature unirrigated blue elderberry yield results harvested in 2018 and 2019

Line graph of the average yield from mature, unirrigated blue elderberries at weekly harvest intervals from June to September.

Figure 2. Mature Harvest Window. This graph shows the average weekly yield of unirrigated mature blue elderberry shrubs according to planting date (2019 harvest season). All ripe berries within approximately 10-12 ft of ground level were hand picked weekly using an 8 foot orchard ladder. Yield is measured as pounds of destemmed ripe berries.

Mature elderberry hedgerow, planted in 2008.
Mature elderberry hedgerow, planted in 2008.
 

Management impacts on mature elderberry yield

  • Variability: Average results suggest that mature yield may increase for 10 years after planting, but per plant yield was variable among shrubs of the same age in the same hedgerow. Genetic differences and many other factors are interacting. 

  • Spacing: Closer spacing appears to decrease per tree yield.  The highest yielding shrubs were spaced at least 20-30 feet from the nearest large shrub or tree.

  • Water availability: Proximity to nearby water sources may increase per plant yield and change the timing of fruiting for un-irrigated blue elderberries, due to their ability to scavenge for water. 

 

Updated August 2024