Brussels Sprouts

 Brassica oleracea (Gemmifera Group)

Last revised January 12, 2010


VARIETIES (approximately 100-180 days from transplanting).

See the Vegetable Variety Selection Resources page to find varieties that have been shown to perform well in the Pacific NW. 

IMPORTANT

Before planting this Crucifer crop, consider the following important factors:

No crucifer crop, or related weed has been present in the field for at least 2 years, 4 years preferable. Crucifer crops include cabbage, cauliflower, broccoli, kale, kohlrabi, Brussels sprouts, Chinese cabbage, all mustards, turnips, rutabagas, radishes etc. Cruciferous weeds include wild radish, wild mustards etc. Also, crucifer plant waste should not have been dumped on these fields. Soil pH should be 6.5 or higher. Soil pH over 6.8 is necessary to manage club root. The application of 1500 lbs/acre of hydrated lime, 6 weeks before planting is recommended for soils with pH less than 7.5 for club root control. Arrange to keep transplanted and direct-seeded fields separate to minimize spread of certain diseases that are more prevalent in transplanted fields.

Brussels Sprouts: Photo credit: Bill Mansour, Oregon State University

SOIL

Brussels sprouts may be grown on a variety of soils but they grow best on a well-drained, loam soil well supplied with organic matter. Sandy loams are preferred for early crops. Adjust soil pH to 6.5 or higher for maximum yields, and avoidance of club root.


SEED AND SEEDBED TREATMENTS

Brussels Sprouts seed number approximately 100,000 per pound, but this crop is most commonly transplanted rather than direct-seeded. Pelletizing is not necessary but primed and coated seed is now becoming popular. Consult your seed dealer about the availability of primed seed.

Use hot water and fungicide-treated seed for seedbeds to protect against several serious seed-borne diseases. Hot water seed treatments are very specific (122 F exactly, for 25 to 30 minutes; the wet seed must then be quickly cooled and dried). The seed treatments are best done by the seed company, and can usually be provided upon request.


TRANSPLANT PRODUCTION

Seed in a greenhouse for an early crop, in a cold frame for a less early crop, and in outdoor seedbeds when the weather is warm enough for germination and growth (above 50 F). In each case seed 5-6 weeks ahead of when the plants are wanted for transplanting.

Four to 6 ounces of high quality, sized and density graded seed will provide enough transplants to plant 1 acre. In the seed-bed use a drill with a scatter shoe to drop 15 to 20 seeds per foot in rows 10 inches apart, or a precision vacuum seeder or belt seeder with three lines per drill.

Greenhouse transplant production

Broadcast seed into flats containing a peat-lite (peat-vermiculite) mix or a sterilized soil and transfer individual plants into other flats when the first true leaves have formed or seed directly into modular flats, styrofoam trays or blocks of a growing medium. Crowding should be avoided.

Provide 1.5-2.5 square inches per plant in modular trays.

Temperatures should be maintained above 45 F at night and below 85 F during the day. Seven days before transplanting start the hardening off process.

Follow the same process in a cold frame, or seed directly into the covered soil after it has been limed, fertilized and fumigated as for outdoor seedbeds.

Seedbeds for transplants

When seedlings are to be grown in a seedbed for production of transplants, choose a site where cole crops have not been grown before or fumigate prior to seeding with an approved material following manufacturer's and label recommendations.

Locate these in an open, well drained area, free of club-root. Lime if necessary, and fertilize with 10-30-10 at 600 lb/acre or its equivalent. Fumigate prior to seeding if the area has been planted to cole crops in the past.


TRANSPLANTING

Transplant to the field about April 15. Space plants 16-18 inches in the row and space rows 36-40 inches apart. Use only healthy plants that are about 6 inches tall and about 6 weeks old. Irrigate immediately after transplanting to set plants firmly into the soil. Use a transplant starter fertilizer solution high in phosphorus when transplanting.


FIELD SEEDING

Due to cost of seed and time required to reach harvest, direct-seeding Brussels sprouts is not recommended. If field seeding is to be done, preparation for direct-seeding needs the same attention a transplant seed-bed area would be given. A fine-textured soil, free of rocks, clods and trash, firm and level, is required for precision seeding.

Use a precision seeder such as a Stanhay, or Gaspardo vacuum planter, to drop two seeds 2 inches apart every 15 inches. After the first true leaves have formed, thin the plants so as to leave one plant at each location. Spacing between rows should be 36 to 40 inches. The use of vermiculite anticrustant is recommended. Or, have solid-set irrigation available to keep soil surface moist and free from crusting until the stand has been established.


FERTILIZER

A soil test is the most accurate guide to fertilizer requirements. The following recommendations are general guidelines for western Oregon.

Good management practices are essential if optimum fertilizer responses are to be realized in the production of Brussels sprouts. These practices include use of recommended varieties, selection of adapted soils, weed control, disease and insect control, good seedbed preparation, proper seeding methods, and timely harvest.

Because of the influence of soil type, climatic conditions, and other cultural practices, crop responses from fertilizer may not always be accurately predicted. Soil test results, field experience, and knowledge of specific crop requirements help determine the nutrients needed and the rate of application.

The fertilizer application for Brussels sprouts should insure adequate levels of all nutrients. Optimum fertilization is intended to produce top quality and yields in keeping with maximum returns.

The suggested fertilizer applications are based on 36-inch row spacing. With decreased row spacings, increased fertilizer rates are suggested.

Recommended soil sampling procedures should be followed in order to estimate fertilizer needs. The Oregon State University Extension Service agent in your county can provide you with soil sampling instructions, soil sample bags, and information sheets.

Transplant Bed Fertilization

Broadcast and work into the transplant bed:

40 to 70 lb N/A.
Apply phosphorus, potassium, sulfur, magnesium, boron, molybdenum, and lime up to the maximum rates suggested below for field applications.
Transplanting Solutions

Dilute solutions of complete fertilizers high in phosphorus promote quick recovery and early growth of transplants. One-half pint of transplanting solution should be injected into the furrow at the roots of each plant at time of transplanting. A transplanting solution may be prepared by dissolving 3 lb 11-48-0 or similar monoammonium phosphate fertilizer in a 55-gallon drum of water.

Field Fertilization

NITROGEN (N):

A total application of 150-200 lb N/A is suggested. Broadcast about half the N just prior to direct seeding or transplanting or band 60-90 lb N/A with the phosphorus. For both direct-seeded and transplanted crops, sidedress 75 to 100 lb N/acre at time of last cultivation, or 1 to 2 weeks before the first harvest. At the higher rates, two applications should be made 2 to 3 weeks apart.

For N solutions having herbicidal effects, see the file Use of Nitrogen Liquid Fertilizer Formulations as Herbicides in Cole Crops.

PHOSPHORUS (P)

Phosphorus fertilizer should be banded at the time of seeding or transplanting. Bands should be located 2-3 inches to the side of the seeds or plants and 3-4 inches deep.

          If the soil test*                      Apply this amount of

          for P reads (ppm):                   phosphate (P2O5) (lb/A):



               0 - 30                                 150 - 200

              30 - 50                                 100 - 150

              Over 50                                  80 - 100

*Assumes extraction procedures similar to those used by the OSU Central Analytical Laboratory. Specific information on soil test procedures is available from the Dept. of Crop and Soil Science.

POTASSIUM (K)

Limit band applications of K to 90 lbs K2O/A. Broadcast remainder of K and work into seedbed prior to planting. The total of N plus K2O in the band should not exceed 90 lb/A. Apply K as follows:

              If the soil test*                Apply this amount of

              for K reads (ppm):               potash (K2O) (lb/A):



                     0 - 150                        150 - 200

                   150 - 200                         90 - 150

                   200 - 250                         60 -  90

                    Over 250                           None

*Assumes extraction procedures similar to those used by the OSU Central Analytical Laboratory. Specific information on soil test procedures is available from the Dept. of Crop and Soil Science.

SULFUR (S)

Include 25-40 lb S/A in the fertilizer program. Sulfur is sometimes contained in fertilizers used to supply other nutrients such as N, P, and K, but may not be present in sufficient quantity.

Plants absorb S in the form of sulfate. Fertilizer materials supply S in the form of sulfate and elemental S. Elemental S must convert to sulfate in the soil before the S becomes avail able to plants. The conversion of elemental S to sulfate is usually rapid for fine ground (less than 40 mesh) material in warm moist soil).

Sulfur in the sulfate form can be applied at planting time. Some S fertilizer materials such as elemental S and ammonium sulfate have an acidifying effect on soil.

The S requirements of crucifers can be provided by:

The application of 25-40 lb S/A in the form of sulfate at or prior to seeding or planting.
Applying 40-50 lb S/A as fine ground (finer than 40 mesh) elemental S the preceding year.
Applying coarser ground elemental S at higher rates and less frequently.
MAGNESIUM (Mg)

When the soil test value for Mg is below 2 meq/100g soil, band 15-20 lb Mg/A at transplanting or seeding time. If Mg deficiency symptoms develop, spray with 10 lb Epsom salts in 100 gal water/A. Magnesium can also be supplied in dolomite, which is a liming material and reduces soil acidity to about the same degree as ground limestone. Dolomite should be mixed into the seedbed at least several weeks in advance of seeding and preferably the preceding year. It can also be supplied by the application of Epsom salts or Sul-Po-Mag fertilizer prior to seeding or transplanting as follows:

Sul-Po-Mag at 150 to 200 lb/acre.
OR Epsom salts at 150 to 200 lb/acre.
OR Dolomitic Limestone at 225 to 275 lb/acre.

BORON (B)

Brussels Sprouts are sensitive to boron deficiency. Apply boron as follows:

            If the soil test*                    Apply this amount

            for B reads (ppm):                      of B (lb/A):



                 0 - 1                             3 - 4 broadcast

                 1 - 3                             1 - 2 broadcast

                Over 3                           1/2 - 1 foliar spray

*Assumes extraction procedures similar to those used by the OSU Central Analytical Laboratory. Specific information on soil test procedures is available from the Dept. of Crop and Soil Science.
A satisfactory foliar spray contains 1 lb B/100 gal water. Fertilizers containing B should not be banded.

Fields East of the Cascades or where winter rainfall is low, and to which the higher rates of boron have been applied, should not normally be planted to beans or cucumbers the following year, as both these crops are extremely sensitive to boron.

LIME

If a mineral soil is below pH 6.3 or an organic soil is below 5.5 and/or the calcium (Ca) level is below 8 meq/100g soil, lime should be applied. Compared to other vegetables, Brussels Sprouts have a fairly high lime requirement.

The application of lime is suggested when the soil pH is below 6.3

              If the SMP Buffer*               Apply this amount

             test for lime reads:                of lime (T/A):



                 Below 5.6                          5 - 7

                 5.7 - 5.9                          4 - 5

                 5.9 - 6.1                          3 - 4

                 6.1 - 6.3                          2 - 3

                 6.3 - 6.6                          1 - 2

                 Over  6.6                           None

*Assumes extraction procedures similar to those used by the OSU Central Analytical Laboratory. Specific information on soil test procedures is available from the Dept. of Crop and Soil Science.
The liming rate is based on 100-score lime. Lime should be mixed into the seedbed at least several weeks before seeding and preferably the preceding year. A lime application is effective over several years.

Some soils may have a fairly high SMP buffer value (over 6.6) and a low pH (below 6.0). This condition can be caused by the application of acidifying fertilizer. In this case the low pH value is temporary and the pH of the soil will increase as the fertilizer completes its reaction with the soil. This temporary "active" acidity from fertilizer is encountered following recent applications of most nitrogen fertilizer materials. Acidifying fertilizers also have a long term acidifying effect on soil that is cumulative and leads to lower SMP buffer readings.

Sandy soils to which fertilizers have not been recently applied sometimes record low pH and high SMP buffer values. In such cases, a light application of lime (1 to 2 ton/A) should suffice to neutralize soil acidity.

For acid soils low in Mg (less than 0.5 meq Mg/100g soil) one T/A of dolomite lime can be used as a Mg source. Dolomite and ground limestone have about the same ability to neutralize soil acidity.

These P, K, Mg, B and lime recommendations are based on soil test values from the Soil Testing Laboratory, OSU, Corvallis, Oregon. They are largely the result of experiments conducted by Oregon State University Agricultural Experiment Station faculty. and are quoted from OSU Fertilizer Guide FG 27.


IRRIGATION

Brussels sprouts are a long season crop. Depending on planting date, seasonal variation and variety, 15-20 inches of water may be required.

Soil type does not affect the amount of total water needed, but does dictate frequency of water application. Lighter soils need more frequent water applications, but less water applied per application.


TOPPING

To stimulate growth of the sprouts at the top of the plant and to provide uniform development for once-over harvesting, top (pinch-off the growing point) the plants when they are almost full-grown and when the lower sprouts have a diameter of about 0.5-0.75 inches.


HARVESTING AND HANDLING

The University of California-Davis has a file on Minimal Processing of Fresh Vegetables that discusses film wrapping and other topics.

Yields of Brussels sprouts are reported to average approximately 140 cwt/acre with good yields at 175 cwt/acre.

Most Brussels sprouts in the northwest are hand harvested. Harvest sprouts when they are round, firm, tight, and of good color. The lower sprouts mature first and should not be left on the plant too long as they will break down and become diseased.

Alternatively, the crop can be once-over mechanically harvested with one of an assortment of European or American strippers.

Deterioration of Brussels sprouts--yellowing of the sprouts and discoloration of the stem end--is rapid at temperatures above 50 F.


STORAGE (Quoted or modified from USDA Ag. Handbook 66 and other sources)

Store Brussels sprouts at 32 F and a relative humidity of 95 to 100%. Brussels sprouts can be kept in good condition for a maximum of 3 to 5 weeks at 32 F. Longer storage may result in black speckling of the leaves, loss of fresh bright green color, decay, wilting, and discoloration of the surface. Rate of deterioration is twice as fast at 40 F as at 32 F. At 50 F and above, deterioration--yellowing of the sprouts and discoloration of the cut surface-- is rapid; yellowing becomes evident within 1 week at 50 F.

A controlled atmosphere of 2.5 to 5% oxygen and 5 to 7.5 % carbon dioxide is helpful to the quality maintenance of Brussels sprouts held at 40 or 50 F but not at 32 F. Oxygen levels below 1% can cause internal discoloration. Controlled atmosphere extends storage about a week at 40 F. Film packaging or film crate liners are useful in preventing moisture loss because transpiration by Brussels sprouts is high even if the relative humidity is kept at the recommended level. The film should be perforated because accumulated volatiles other than carbon dioxide produced by the Brussels sprouts results in objectionable odor or flavor and because a build-up of 20 % carbon dioxide in the atmosphere can cause injury. As with broccoli, sufficient air circulation and spacing between packages are desirable to allow good cooling and to prevent yellowing and decay. Also, Brussels sprouts should not be stored with fruits because ethylene from the fruits will accelerate yellowing and can cause abscission of leaves.


PACKAGING

Film packaging is recommended to prevent wilting.

Brussels sprouts are most commonly packaged in 25-lb loose-pack cartons or in flats or cartons containing 12 cups of 10 ounces each.

Tags:

Fresh Market Vegetable Production, Brussels sprouts, Vegetable production