Best Management Practices for Broccoli
» Broccoli production involves decisions on varieties, planting times and methods, fertilization, irrigation, harvest methods, and post-harvest handling.
» Variety selection and fertilization can differ with spring and fall broccoli crops.
» Plant population size impacts head size and rate of development.
Broccoli is a cool-season vegetable that is grown as an early
spring or fall crop in many parts of the United States.
Broccoli varieties differ in their tolerance of heat and cold, so
it is important to select varieties that are appropriate for the
planting period, location, and type of production.1 Varieties
for fall production will need to be heat tolerant. Varieties for
spring production need to be cold tolerant, especially in
areas that may experience frosts or freezes after planting.2
Additional selection criteria include the days-to-harvest
rating (75 to 140 days), resistance to diseases, yield
potential, and head quality. Quality traits include heads with
small, uniform beads, a blue-green to bright-green color, a
dome shape, and heads that stand above the leaves for
ease of harvest. Undesirable traits include a tendency to
form hollow stems, brown or yellow beads, bracts within
heads, uneven bead size, and excessive branching.1,3
Broccoli is planted by both direct seeding and transplanting.
Direct seeding can result in more weed competition and can
add up to 20 days from field planting to harvest, as
compared to transplanting. However, labor and supply costs
are lower with direct seeding.3 In many cases, the planting
method is determined by the equipment available. In the
Salinas Valley, most of the broccoli is direct seeded because
that planting equipment is also used for planting lettuce. For
transplant production, a minimum cell diameter of 1 inch is
recommended.3 Four- to five-week-old seedlings with four to
five true leaves are best for transplanting, and hardening of
seedlings before planting improves stand establishment.
PLANTING TIMES AND CONDITIONS
Broccoli seed can germinate at soil temperatures as low as
40°F, while the optimum range for seed germination is 45°
to 85°F. Therefore, the time of direct seeding a spring crop
should be based on the average date of soil temperatures
reaching 45°F in the local area. Late spring plantings should
be avoided in areas where summer temperatures regularly
go above 90°F, as plants can bolt and unacceptable levels of
head distortion can occur when heads mature during the
Planting of fall crops usually starts in late June and continues
through late August. The varieties planted in the summer
need to be heat tolerant in order to establish properly.
When transplanting into raised beds with plastic mulch,
white-on-black plastic should be used for summer plantings
to prevent excessively high soil temperatures. There are
some areas of the U. S. where broccoli is grown year-round.
Recommendations for plant spacing vary considerably
depending on the growing region, intended market, and
harvest method (described below). Much of the broccoli
produced in California is grown for fresh market sales, with a
significant amount of the crop exported to countries such as
Japan. This market desires relatively small (4- to 5-inch),
crown-cut heads. To produce these heads, broccoli is
planted at populations of up to 40,000 plants per acre.
Typical plantings are double rows on 38- to 42-inch raised
beds with 12 to 14 inches between rows and 5 to 6 inches
between plants in the row. Some growers use wide beds, 76
to 80-inches wide with four rows per bed.1
In other areas, different growing conditions and a market
preference for larger heads require wider plant spacings
and lower populations. Recommended planting
arrangements in New York are 3 to 4 rows per bed with a 17
-inch row spacing and 7- to 10-inch in-row spacing for direct-
seeded crops. For transplanted crops, row spacings of 24 to
36 inches with 8- to 12-inch plant spacing is recommended
for large head production, and 3 rows on 60-inch beds (20-
inch row spacing) for crown-cut heads.3 The Midwest
Vegetable Production Guide recommends a 36-inch row
spacing with a 12- to 18 inch-in-row plant spacing.4
Increased spacing results in larger heads and faster, more
uniform development. However, wider spacing also tends to
result in higher levels of hollow stem as plants grow more
quickly. Reduced plant spacing (higher plant populations)
results in smaller heads, slower plant development, and an
extended harvest period, but lower levels of hollow stem.5
Broccoli is a nutrient-demanding crop, and fertilization rates
should be based on soil nutrient tests. Over-fertilization can
lead to increased levels of hollow stem and unacceptable
nutrient levels in leached and run-off water. Fertilizer
applications are usually split into pre-plant and one or more
post-plant applications as sidedressings or through drip
irrigation systems. Recommendations for total nitrogen (N)
amounts range from 80 to 240 lb/acre depending on the
region, soil organic matter levels, and cropping season.
About half of this is applied as a pre-plant broadcast or
banded applications. The remainder is applied in one or two
applications starting at 4 weeks after direct seeding (2 to 3
weeks after transplanting).1,3,4 Phosphorus (P) and
potassium (K) are applied pre-plant with recommended
rates of P2O5 ranging from 25 to 200 lb/acre and rates of
K2O ranging from 0 to 160 lb/acre depending on the region
and soil nutrient test levels. Additions of boron and zinc may
be needed in soils that are deficient in these nutrients.1,3,4
Broccoli requires an adequate supply of soil moisture to
produce maximum yields and quality. However,
overwatering can cause the development of watery heads,
hollow stems, and root rots. Appropriate moisture levels are
the most critical during the period of head formation near
the end of the season. Irrigation is applied mostly with
overhead sprinkler and drip irrigation systems, and the most
common methods used vary by region. Some growers start
with sprinklers after planting or transplanting and then
switch to drip irrigation once the crop is established. Drip
irrigation systems usually provide higher water-use efficiency
and they can also reduce the amount of fertilizer needed by
as much as 20 or 30%.1 Overhead irrigation can help spread
some fungal and bacterial pathogens, so lower disease
levels may occur where drip systems are used.
All broccoli harvesting is done by hand, but there are various
harvest techniques used depending on the intended market.
For all systems, heads should be firm and well developed,
but not opening. For fresh market sales, heads are usually
harvested two to three times at 3- to 4-day intervals,
depending on market price and head quality.1,3 Heads
harvested for fresh market are typically field packed with 22
to 23 lb per box. For markets that want larger heads, heads
are harvested when they are 3 to 8 inches in diameter, and
stalks are cut about 8 inches in length. Sometimes two to
four heads are banded together in a bunch (Figure 1). Crown
-cut heads are usually 4 to 6 inches in diameter and cut
approximately 5 inches long. These heads are not bunched.
Other harvest/market options are field-cut florets for fresh
market and harvest for processing (freezing).1,3
POST HARVEST HANDLING
Field-packed boxes should be kept out of the sun and
quickly transported to a packing facility for cooling to
preserve quality and shelf life. Standard practice is to use
water or ice-based systems (liquid icing) within four hours of
harvest to cool the crop to 35°F. Forced-air cooling can also
be used, but this takes longer and can dehydrate the heads.1,3
After cooling, boxes should be stored at 32°F at 95% RH.
This usually allows a shelf life of 21 to 28 days. Storage at
41°F results in a shelf life of 10 to 14 days. Broccoli is very
sensitive to exposure to ethylene, which causes heads to
yellow, making them unmarketable.
1 LeStrange, M., Cahn, M., Koike, S., Smith, R., Daugovish, O., Fennimore, S., Natwick, E., Dara, S., Takele, E., and Cantwell, M. 2010. Broccoli production in California. UC Vegetable Research and Information Center. Vegetable Production Series. Publication 7211.
2 Kaiser, C. and Ernst, M. 2014. Broccoli. University of Kentucky, Center for Crop Diversity Crop Profile.
3 Reiners, S., Bellinder, R., Curtis, P., Helms, M., Landers, A., McGrath, M., Nault, B., and Seaman, A. 2017. Cornell integrated crop and pest management guidelines for commercial vegetable production.
4 Egel, D., Foster, R., Maynard, E., Weller, S., Babadoost, M., Nair, A., Rivard, C., Kennelly, M., Hausbedk, M., Hutchinson, B., Eaton, T., Welty, C., and Miller, S. 2017. Midwest vegetable production guide for commercial growers 2017.
5 Björkman, T. and Shail, J. 2011. Maximum crown-cut broccoli yield for New York. Eastern Broccoli Project report.
For additional agronomic information, please contact your local seed representative. Developed in partnership with Technology Development & Agronomy by Monsanto.
Individual results may vary, and performance may vary from location to location and from year to year. The information provided in this communication may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. The recommendations in this article are based upon information obtained from the cited sources and should be used as a quick reference for information about broccoli production practices. The content of this article should not be substituted for the professional opinion of a producer, grower, agronomist, plant pathologist, and similar professional dealing with this specific crop. SEMINIS DOES NOT WARRANT THE ACCURACY OF ANY INFORMATION OR TECHNICAL ADVICE PROVIDED HEREIN AND DISCLAIMS ALL LIABILITY FOR ANY CLAIM INVOLVING SUCH INFORMATION OR ADVICE. 170826150359 100917DME
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