Broccoli

Growing Broccoli

Introduction

Broccoli is a member of the Brassica family along with brussels sprouts, cabbage, cauliflower, kale and rocket. It is an annual plant which can be planted as seed or seedlings, and a cool climate vegetable well suited to Canberra.

Types of broccoli include those which produce a main head (common supermarket broccoli varieties), sprouting broccoli which have a number of small, looser heads, and broccoli raab or rapini, a branching type of broccoli. Romanesco (an Italian heirloom variety) has a pale green head with a whorled spiraling pattern. Chinese broccoli or gai lan is a quick growing Asian green which doesn’t form heads; the whole plant is eaten. Broccolini has been developed by crossing main head type broccoli with gai lan.

Broccoli seedlings commonly sold in Canberra are mostly main head varieties, including Marathon, Green Dragon and Waltham. Home gardeners purchasing seeds have access to many more varieties. Seedlings of other varieties such as Broccoli di Ciccio (an early variety with vigorous side shoots), and Broccoli “Piracicaba’’ (non-heading with prolific side shoots) are occasionally available from local seedling producers.

The harvest period could be extended by making smaller plantings every two weeks or as suggested by seed sellers, planting several varieties with differing growing weeks needed to reach harvest. Let us know how different varieties have performed in Canberra conditions if you have done this.

Site and soil

Soil should be well drained with a pH around 6-7and rich in organic matter as broccoli is a heavy feeder. It is usually a cool season crop, so plant it on a site that will get plenty of sun. In Canberra, plant in Spring or late Summer, early Autumn so the plants are well established before Winter. If temperatures are too warm, broccoli (and other brassicas) may bolt, running to flower before the plant fills out.

Planting

Sow seeds in December/January. Some gardeners report difficulty with growing broccoli from seed. The seed is quite fine and often started in trays where the seedlings can be more easily protected from pests. These can be transferred to small pots or punnets and grown on for transplanting into the garden when they are around 10 cm tall. Space plants 50-60 cm apart to optimise production of side shoots.

Cultivation

Keep broccoli well weeded, watered and mulched. Broccoli seedlings may bolt if not regularly watered.

Harvesting

Broccoli should initially be harvested while the main head is still tight, and the flowers are yet to open. In most main heading varieties cutting the head will stimulate the production of side shoots, prolonging the harvest for some weeks from well grown plants.

Problems

Broccoli is particularly susceptible to white cabbage butterflies. Plants, particularly while small, should be protected with netting, or regularly inspected to remove butterfly eggs and caterpillars by hand. If grey aphids appear (often on older plants) these can be hosed off. Some gardeners recommend waiting until the end of February/early March before planting seedlings to reduce attacks by cabbage butterflies. Decoy cut-out likenesses of the cabbage butterfly may also give some protection to seedlings. Broccoli is often eaten by rats