Brussels sprouts take a relatively long time to grow, but do not like summer heat. The plant also grows in summer, but does not develop the firm, compact Brussels sprouts. They thrive best in cool weather. Light night frosts usually do them no harm either. The best time to sow them is in June.

The soil should be fertile and well drained, preferably in full sun for the young plants. The soil should be well loosened to a depth of about 15cm and enriched with organic compost as early as May. This allows the compost to decompose and is firm enough when the seeds are sown. The ideal pH value of the soil is between 6.5 and 7.0. 

About 2 weeks after the soil has been prepared, add an organic, low-nitrogen fertiliser to the soil, spreading it well over the entire area with a rake, but not undermining it. 

The seeds of the Brussels sprouts are pressed two centimetres deep into the soil, 3 seeds at a time. Leave a space of about 50cm between the groups of seeds. After planting the seeds, water the soil well. The seeds will start to germinate after 4-7 days. Depending on the weather, the seeds should be watered every day, the soil must not dry out. 

When the Brussels sprout seedlings are 5cm tall, they can be thinned out. The two weakest per group are cut off just above the soil. Throughout the growing season, the plants need to be watered regularly. 

When the plants have reached a size of about 10cm, they should be fertilised again. Brussels sprouts need a lot of fertiliser, but the sprouts will not develop properly if the fertiliser contains too much nitrogen. From late summer onwards, fertiliser no longer needs to be applied.

Ideally, Brussels sprouts should be planted where beans or peas grew the previous year. Avoid sowing Brussels sprouts where savoy cabbage, kohlrabi, kale or broccoli have stood within the last three years, as these often leave plant diseases in the soil that can be transferred to Brussels sprouts.

The Brussels sprouts can be harvested when the heads have a diameter of 3-4cm, they should be light green and firm.