Photo Credit: Robin Follette
Family: Brassicaceae
Genus and Species: Brassica oleracea
Climate
Brussels sprouts are often referred to as a cole crop. Brussels sprouts need a long cool growing season. Brussels sprouts can withstand hard frosts and even snow. Flavor improves with cooler temperatures because plant cells are working to convert starches to sugars to protect the plant against the cold. The result is a sweet, fresh taste that surpasses that of store-bought greens.
Brussels sprouts become puffy and soft when they mature at temperatures above 80°F and stop growing at temperatures below 52°F. At maturity, warm, sunny days and light frosts at night are ideal to produce tender, sweet sprouts.
Soil
Crop rotation is especially important with Brussels sprouts and other members of the Brassicaceae (previously referred to as the Cruciferae or crucifer) family that includes kale, radish, mustard greens, turnips, and broccoli. 2 - 4 years between plantings of the same family is recommended.
Brussels sprouts prefer well-drained, loam soils rich in organic matter with a pH of 6.0 and above. Sandy loam soils are fine for earlier plantings of Brussels sprouts.
Spacing
Brussels sprouts are a rather large plant that may grow to be 2'-3' with an umbrella like foliage. Space plants at 18"-24" within the row and space rows at 30" apart. Stake the plants in areas with strong winds.
Direct Seeding
A well-prepared seedbed with adequate moisture is a must for direct seeded Brussels sprouts. Sow Brussels sprouts seed 1/4"- 1/2" deep, every 18"-24" within rows spaced 30" apart. Gently press the soil after planting to ensure the seed is in contact with the soil.
Brussels sprouts require a long growing season so indoor seeding may be required to provide sufficient time for adequate growth. Plan on sowing Brussels sprouts seed 80-100 days before the first hard frost in your area to allow for adequate growth. Adjust this estimate, as needed depending on variety and local conditions.
Seeding For Transplants
Sow Brussels sprouts seed into flats, cells, or soil blocks of soil-less mix at 3-4 seeds per inch/unit. Ideal temperatures for Brussels sprout growth are between 45°F at night and 85°F during the day. Begin hardening off the seedlings seven days before transplanting.
Germination
These seeds germinate best in soils around 45°F-85°F.
Germination will take 4-20 days.
Transplanting Into the Garden
Transplant Brussels sprouts seedlings at 6-8 weeks, 3-4 weeks before the last spring frost. Brussels srouts seedlings should be set out at 18"-24" within rows spaced 30" apart.
Watering
An even moisture supply is needed for transplants to become established and to produce good yields. Never let the seedbed dry out. Sandy loam soils may require two to three waterings per day. You must maintain adequate moisture until seedlings are well established.
Harvesting
Harvest Brussels sprouts that are firm and well formed from the bottom up when they reach 1" - 1-1/2" inches wide. Harvesting of the Brussels sprouts may continue for several weeks. The upper Brussels sprouts will continue to form and grow as the lower ones are harvested.
Post-Harvest Handling
Brussels sprouts are highly perishable. Brussels sprouts respiration rate is very high and it is therefore necessary to hydro cool Brussels sprouts very soon after harvest and to keep them cool. Hydro cooling is the process of spraying or immersing vegetables in chilled water.
Storage
Brussels sprouts should be stored at 32°F with a relative humidity of between 95% and 100%. Brussels sprouts can be kept in good condition for a maximum of 3 to 5 weeks at 32°F. The rate of deterioration of Brussels sprouts escalates significantly at temperatures of 40°F and above.
Brussels sprouts require sufficient air circulation 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.
Diseases
Club Root, Black Rot, Black Leg, Wirestem, Alternaria Leafspot, and Downy Mildew
Pests
Aphids, Cabbage Loopers, Imported Cabbageworm, Cutworms, Flea Beetles, and Diamond Back Moth
References
Weekend Gardener, "Brussels Sprouts", Chestnut Software, Inc,http://www.chestnut-sw.com/seeds/vegseed/brussels.htm, Accessed 2003-01-01.
Bradley, F. M. and Ellis, B. W.(Ed.). (1992), Rodale's All-New Encyclopedia of Organic Gardening: The Indispensable Resource for Every Gardener, Emmaus, Pennsylvania: Rodale Press.
Oregon State University, "Brussels Sprouts, Commercial Vegetable Production Guide", Last modified 2002-12-26, Oregon State University, http://www.orst.edu/dept/NWREC/brussprt.html, Accessed 2003-01-01.