How to Make Winter Broccoli Bloom

Choose the Right Crop

• Several types of broccoli grow well during the cool season. Traditional broccoli, exhibiting the thick, green crowns that most people associate with broccoli, grows well in cold weather but detests temperatures above 80 degrees Fahrenheit. Broccoli raab (Brassica ruvo) is a longer, bitterer broccoli specimen that is very frost-tolerant. Chinese broccoli (Brassica alboglabra), also known as Chinese kale, does well during the winter in warm areas and is longer than broccoli, with wider leaves. All are annuals.

Time Planting

• Because it is a cool-season vegetable, broccoli is normally grown as a fall or spring crop. This means you can plant it in spring by sowing seeds indoors 7 to 9 weeks before the last frost date, or in fall by sowing directly in the ground 85 to 100 days before the first predicted fall frost. If you live in a warmer area, you may be able to grow broccoli in wintertime by planting earlier in spring or later in fall.

Leave Until Bloom

• Broccoli doesn’t need any special help in order to bloom in wintertime. All it needs are the right temperatures and to be left in the ground long enough to reach the flowering stage. Since broccolis are hardy, withstanding temperatures down to 40 degrees, you can grow them through the winter in warm climates. Allow the plant to grow past the stage where recognizable tight green buds have formed. These are the incipient flowers, so leave in the ground to bloom. Once they've flowered, you can leave them to grow seed, or you can harvest for use in salads.

Harvest Before Heat

• Because broccoli is a cool-season crop, it becomes bitter very quickly when hot weather hits. Whether you aim to harvest your winter broccoli when it is still in its recognizable vegetable stage or once flowers have already bloomed, keep an eye on the forecast. It tastes best when harvested before flowers bloom, but if you plan to wait past that point, keep an eye on the forecast and harvest before temperatures climb to 80 degrees. A layer of mulch will extend the season a bit by keeping soil temperatures down.