How Much Should I Water Broccoli Plants?

Broccoli is a cool-season vegetable that can be included in your backyard garden provided the right conditions are achieved. The plants do best in temperatures between 70 and 85 degrees Fahrenheit, and like most vegetables they require full sun, according to the University of Minnesota Extension. Proper watering is essential too, because the plants need a moist soil for optimum results.

Broccoli needs about 1 to 2 inches of water each week during the growing season, notes the Utah State University Cooperative Extension. During wet and rainy periods, rainfall may meet these needs. When it does not, you must irrigate the plants to ensure they get enough water for proper growth and development.

For best results, water broccoli with deep occasional irrigations as opposed to more frequent but shorter waterings. When rainfall does not supply all the water needs, water your plants once a week. For example, if your area has received a 1/2 inch of rain, you'll need to water the plants so they get an additional half to 1-1/2 inches.

Spreading mulch around your broccoli plants can help keep the soil moist and allows it to remain cool and prevent excessive evaporation, according to Ohio State University Extension. In addition, mulch can help prevent weeds. Use an organic mulch such as straw or grass clippings, and wait until the weather warms up before applying it.

Improper irrigation -- including too much, too little or uneven watering -- can make broccoli plants susceptible to some diseases. For example, overwatering these plants can cause a fungal condition called downy mildew, notes Minnesota University Extension. Gray leaf spot and black leaf spot -- two more fungal conditions -- can also develop as a result of improper watering techniques such as overhead watering.