Planting Flowers for Honey Bees in Almonds
Steve Peterson
AgPollen, LLC
Funded by CDFA/Project Apis m.
September 6, 2013
Almonds are dependent on bees for pollination and the California crop requires about twothirds of all the honey bees in the U.S. to accomplish the task. The bloom is short lived (usually from
mid-February to early March) and beekeepers typically need to move the bees to another crop (such as
cherries, plums, or to a location where wild plants are in bloom) shortly afterwards. Often, the bees will
need to be fed syrup and protein supplements because this is a time of rapid colony growth. If almond
growers planted flowering plants between the almond rows, the honey bees would likely not need to be
moved or fed so soon.
Xerces Society has proposed a mix of native wildflowers that are low growing, bloom early, and
break down by mid-Summer. Project Apis m (PAm) has developed a mix of non-native flowering plants
that have similar characteristics. In addition, PAm also is promoting rapini (Brassica rapa) as an early
blooming crop that could benefit honey bees in almonds. This report covers findings for flower mixes
planted for the 2012 and 2013 field seasons in Stanislaus County, California.
Methods:
2011-12. This study was conducted in a one-year old almond orchard in Stanislaus County
California. A more mature orchard was located directly south of the orchard and 2 colonies of honey
bees were supplied to that orchard. The blend of 6 species and their percentages by number of seeds
was as follow:
Species
Nemophila maculata
Nemophila menziesii
Eschscholzia californica
Phacelia campanularia
Lupinus bicolor
Collinsia heterophyllus
Common Name
Five spot
Baby blue eyes
California Poppy
California Bluebells
Bicolor Lupine
Chinese houses
Percent of Blend
20.0%
15.0%
20.0%
20.0%
10.0%
15.0%
Seed suppliers were Pacific Coast Seed (Livermore, CA, www.pcseed.com), Wildseed Farms
(Fredricksburg, TX, www.wildseedfarms.com) and Hedgerow Farms (Winters, CA,
www.hedgerowfarms.com). 70% of seed cost was attributed to two species, five spot, and bicolor
lupine.
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Seed Cost
Five spot
Baby blue eyes
CA poppy
CA bluebells
Bicolor lupine
Chinese houses
Seeds were planted on two dates: 10/12/2011 (“early planting”) and 11/13/2011 (“late planting”) using
a Schmeiser, 4-foot no-till seed drill. The seeds were planted in the center of the strip between the
almond trees and did not receive any irrigation. The target density was 42 seeds per square foot or 19
pounds per acre. Seed was planted in a 4 foot strip, in every other row of almonds, covering 200 acres
of almonds. The cost was $27.97 per acre of almonds. If the strips were condensed into a solid planting,
it would cover 18 acres, at a cost of $310.83 per acre.
Honey bee visitation was documented by counting bees seen on flowers in a strip for 5 minutes at a
slow walking pace. Observations were made in an area where the weeds were less prevalent, between
11:30 am and 4 pm.
2012-13. Three plantings were made adjacent to an almond orchard in 2013. These were the
same seed mix as in 2012 with a small amount of Great Valley Phacelia, Phacelia ciliata (Xerces mix), a
blend of clovers, alyssum and lana vetch (PAm mix) and rapini (Brassica rapa). All were planted on
10/25/12, with the Xerces mix at 18.8 lb./acre, the PAm mix at 17.8 lb./acre and the rapini at 4.8
lb./acre. Purple tansy (Phacelia tanacetifolia) was broadcast seeded in a nearby ravine and was
monitored for bloom timing as well. This species is highly attractive to bees but grows to 2 to 4 feet.
Grasses germinated heavily in the plots after seeding. The grass herbicide Poast was applied with a
backpack sprayer in a 1.5% solution on 1/4/13. Grass seedlings were 2 to 3 inches tall at that time.
Results:
2011-12. Most seed appeared to germinated well, but little rain fell between mid-November
and Mid-January. Cool temperatures also kept growth to a minimum during this time. When rain began
falling more regularly from mid-January through April, the plants grew steadily. Grass weeds became
abundant in much of the planted area, but in some areas, usually hilltops, there was less weed
competition.
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Oct
Nov
Dec
Jan
Feb
Mar
Apr
Total
Inches of Rain
2011-12 2012-13
1.36
0.12
0.82
1.59
0.25
2.91
1.43
1.16
0.97
0.32
3.01
0.19
2.28
0.34
10.12
6.63
The first plant to bloom in 2012 was five spot on February 9th, which was about 9 days ahead of the
nearby almonds. The late planting bloomed 6 to 26 days later than the early planting, depending on the
species.
Five spot
Baby blue eyes
CA bluebells
CA poppy
Bicolor Lupine
Chinese houses
Early planting
First bloom
2/9/2012
2/17/2012
2/21/2012
3/2/2012
3/9/2012
3/9/2012
Late planting
First bloom
3/2/2012
3/2/2012
3/15/2012
3/18/2012
3/15/2012
4/4/12
Days apart
22
14
23
16
6
26
Bloom Timing 2012
5/11/2012
4/21/2012
4/1/2012
3/12/2012
2/21/2012
First bloom
2/1/2012
Start Full Bloom
1/12/2012
End Full Bloom
12/23/2011
Five spot Baby blue
CA
CA poppy Bicolor
eyes bluebells
Lupine
Chinese
houses
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Honey bees favored five spot through most of March and early April. California poppy began blooming
heavily as the five spot went into decline in the middle of April.
Honey bees observed in 5 minutes
200
180
Five spot
Baby blue eyes
CA blue bells
CA poppy
160
140
120
100
80
60
40
20
0
3/2
3/12
3/22
4/1
4/11
4/21
5/1
5/11
Other bees seen visiting the flowers were bumble bees (Bombus vosnesenskii queens) on Chinese
houses, blue orchard bees (Osmia lignaria) on the five spot and Chinese houses and small sweat bees
(Lasioglossum spp.) on the California poppies, baby blue eyes and California blue bells.
2012-13. About one-third less rain fell over the winter of 2012-13, compared with the previous
season. In particular, February, March and April were extremely dry. Seedlings germinated in the fall
but the plants remained small through February. Consequently bloom timing was later than in 2012 and
flowers were less abundant. The herbicide Poast worked well to control post-emergent grass weeds in
the plots.
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Xerces mix
PAm mix
Rapini
Species
Five spot
Baby blue eyes
Calif. bluebells
Calif. poppy
Bicolor Lupine
Chinese houses
Great Valley Phacelia
Lana vetch
Balansa clover
Alyssum
Crimson clover
Rapini
Purple tansy
First bloom
2/27/13
3/12/13
3/25/13
3/24/13
3/4/13
4/8/13
2/27/13
3/12/13
3/12/13
3/5/13
4/8/13
2/21/13
3/29/13
Full bloom
3/13/13
3/24/13
5/2/13*
3/29/13
3/13/13
4/18/13
3/19/13
3/12/13
3/3/13
*Planted 1/30/13.
Xerces mix: Five spot bloomed 18 days later and poppies bloomed 22 days later in 2013. Bicolor lupine
bloomed about the same time as last year. California bluebells bloomed about 10 days later than the
previous year and Chinese house began blooming about 30 days later this year. Great valley Phacelia
bloomed with similar timing to five-spot and was very attractive to bees.
PAm mix: The lana vetch, balansa clover and alyssum all came into bloom around 3/12/13 and the
crimson clover began blooming around 4/8/13. The other clovers in the mix were not seen blooming.
The lana vetch was the dominant plant in the mix and spread vines over the clovers, shading them.
Honey bees were seen visiting the lana vetch, but not the clovers.
Rapini: The rapini came into bloom before any of the other flowering species (2/21/13) in this year. It
bloomed heavily and attracted honey bees for 3 weeks in March and was finished blooming by 4/2/13.
Honey bee visits in 5 minutes:
Flower species:
Rapini
Lana vetch
Five spot
Great valley Phacelia
Baby blue eyes
3/11/13
32
0
0
0
0
3/24/13
60
55
46
9
4
4/18/13
0
5
0
0
0
Conclusions: Without irrigation in central California, the blooming forbs planted in this study thrived
when rainfall came in normal amounts in the early spring. As we saw in 2012, five spot can bloom ahead
of almonds and will continue to bloom after almonds are finished blooming. In 2013, rainfall was
5
meager in February and March and this had a detrimental effect on the plants. Despite this, the rapini
grew well and bloomed for 3 weeks in March. With more moisture it may be possible for it to bloom
longer, and possibly begin flowering ahead of almonds. Great valley Phacelia bloomed as early as five
spot and was attractive to bees as well, making it a good potential addition to the Xerces mix or a good
stand alone wildflower. Purple tansy began blooming in late March, 2 weeks after almonds were
finished. This wildflower could be useful where plant height is not an issue and bee forage is needed in
April. The grass herbicide Poast at 1.5% worked well to control grass seedlings.
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