How to sow broccoli, a nutrient-rich vegetable

Broccoli is a vegetable from the Brassicaceae family, valued for its green inflorescences rich in vitamins and minerals. Widely used in cooking, it can be consumed raw or cooked, and is a health asset in many dishes. Sowing broccoli allows you to enjoy a wide variety of options and to fully control the growing cycle, from seed to harvest.

Growing broccoli from seeds is also more economical than buying plants, and allows for a generous yield of vegetables in a small space. This comprehensive guide explains step by step how to sow broccoli, indoors or in the open ground.

Why sow broccoli?

Sowing broccoli has many advantages:

• Cost reduction: seed packets are cheaper than established plants.
• Wider variety selection: you have access to early, late, or disease-resistant varieties.
• Control over the growing cycle: sowing yourself allows you to adapt the growing dates to your climate.
• Staggered harvest: by staggering sowings, you extend the harvests throughout the season.
• Adaptability: young plants from sowing adapt better to your soil and local conditions.

When to sow broccoli?

The ideal time to sow broccoli depends on the type of cultivation planned and the variety:

• Under cover or in buckets (indoors, greenhouse, cold frame): from February to March, for transplanting in April and harvesting in early summer.
• In open ground (directly in the garden): from April to June, once the frosts have passed, for summer or autumn harvests.
• At the end of summer (winter broccoli sowing): from August to September, to harvest the following spring in regions with a mild climate.

Sowing under cover allows for early cultivation, while sowing in open ground is simpler but more dependent on weather conditions.

Where to sow broccoli?

Broccoli prefers the following conditions:

• In open ground: in a sunny, well-ventilated vegetable garden.
• In pots: possible with a container of at least 40 litres, deep and well-drained.
• Exposure: in full sun or partial shade in very hot regions.
• Soil: rich in humus, moist but well-drained, slightly clayey or loamy. Soil that is too dry or acidic hinders its growth.

Depending on your space and goals, you can choose either cultivation method.

The necessary equipment for sowing broccoli

• A sowing tool or sowing board: for even distribution of seeds.
• Seed trays or pots: for early sowings indoors or under cover.
• An appropriate substrate: a light potting mix, enriched with compost or a mix of potting soil/sand.
• A mini-greenhouse or plastic film: to maintain the heat and moisture necessary for germination.
• A watering can with a fine rose: to avoid displacing the seeds during watering.
• A dibber or small rake: to aerate and prepare the soil in open ground.

Practical steps for sowing broccoli

In trays (indoors or under cover)

• Preparing the substrate: fill the trays with a mixture of light, sifted potting soil. Lightly moisten.
• Choosing the seeds: select a variety suitable for the season and your climate (e.g.: broccoli ‘Calabrese’, ‘Romanesco’…).
• Sowing the seeds: sow 1 to 2 seeds per tray, at about 1 cm deep.
• Covering: add a thin layer of potting soil on top, lightly compact.
• Watering: moisten with a watering can with a fine rose without over-saturating.
• Placement: place the trays in a bright location, at 15-20°C, sheltered from drafts.
• Monitoring: germination occurs within 7 to 10 days. Keep the substrate moist, but not waterlogged.

In open ground

• Preparing the soil: dig deeply to loosen. Enrich with well-matured compost.
• Sowing the seeds: mark out rows spaced 40 cm apart, then sow one seed every 3 to 5 cm.
• Covering: cover with a thin layer of soil, lightly compact.
• Watering: water immediately after sowing, without excess.
• Maintenance: weed regularly to prevent competition from adventive plants.

After sowing: care and maintenance of young plants

• Thinning: when the plants reach 5 to 7 cm, keep only the strongest, at a spacing of one plant every 50 to 70 cm.
• Transplanting: for seedlings in trays, transplant into open ground after 4 to 6 weeks, when they have 4 to 5 true leaves.

• Watering: maintain consistent moisture, especially during dry periods, without wetting the foliage.
• Exposure: ensure good light, without prolonged exposure to cold winds.
• Soil protection: mulch at the base to retain moisture and limit weed growth.
• Pest monitoring: watch for pests (flea beetles, caterpillars, aphids) and diseases such as cabbage root rot. Encourage crop rotation.