Growing Broccoli: Seed to Harvest

Broccoli is one of my favourite crops to grow — not only because I love eating it fresh from the garden, but because it’s also perfect for freezing (just blanch it first!). It’s a versatile, cool-season vegetable that’s surprisingly easy to grow, even for beginners.

I grow broccoli from autumn to early spring in my frost-free garden, which also helps reduce pest pressure. Even though the plants get big and leafy, broccoli grows well in containers too — just don’t expect huge heads.

Broccoli is a brassica plant which is part of the cabbage and mustard family. The most prominent members besides broccoli are cabbages, cauliflower, and brussels sprouts.

When to Plant Broccoli

Broccoli prefers cooler seasons — either early spring or autumn. The exact timing really depends on your climate. In frost-free zones, you can plant from autumn through early spring (depending on the chosen variety). In colder regions, start seeds indoors a few weeks before your last frost date, then transplant them as soon as conditions allow in order to avoid growing them in the middle of summer.

Starting Broccoli: Transplants or Direct Sow?

To get a head start, sowing seeds indoors is ideal. Even if the weather is suitable for direct sowing, I still sow them in trays — it’s easier to keep the seedlings happy and monitor their progress. This is not only a good option to protect the plants from the weather, but it can also help if you have a small growing space. I start my broccoli seeds in trays, when the tomato plants are nearing their end. As soon as I have to take them out of the garden, I can put in the broccoli. This way I can grow more in valuable growing space.

Of course, buying healthy seedlings from a nursery is also a good option, especially if you’re short on time or just want to make sure you have a successful start.

If you’re sowing in trays or direct, make sure the soil stays consistently moist. I usually place two seeds per cell to increase the chances of success and thin them out later. Plant the seeds about 1 cm deep and water them in well. You can cover the trays with plastic wrap until germination to hold in the moisture.

Transplanting & Spacing

Once your broccoli seedlings are about 4–6 weeks old (or around 15 cm tall), they’re ready to move into the garden. I space mine about 45 cm apart to give them plenty of airflow and room for their large leaves. Adequate spacing is especially important in humid climates, where fungal issues can spread quickly.

If you’re tight on space, try interplanting. I like to tuck lettuce or other low-growing crops between broccoli plants. Lettuce doesn’t compete much for space or light and actually benefits from the shade cast by broccoli leaves as the season warms up.

Watering & Fertilizer

Broccoli needs consistent moisture to grow well. The soil should stay evenly moist — not soggy, but not dry. I try to mulch my beds to help with water retention (though I’ll admit, I skip it more often than I should!).

Midway through the growing season, I give my plants a boost with a gentle organic fertilizer like fish emulsion or kelp. Be cautious with high-nitrogen fertilizers — they’ll grow lush leaves but can delay or reduce head formation if used too late in the season.

For best results, use a balanced fertilizer early in the season to support leafy growth, then switch to a lower-nitrogen formula as the heads start forming. Compost is also a great option for feeding your soil and your plants naturally.

Pest & Protection

Broccoli, like all brassicas, is a magnet for pests — especially cabbage moths or the cabbage white butterfly. The best way to protect your plants is with physical barriers. Netting or row covers keep the moths from laying eggs on your plants and saves trouble down the line.

In the cooler months, I rarely have pest issues, but as the weather warms up, I often see the little white butterflies circling my broccoli. Since I’m not great at keeping covers on, I inspect the plants regularly for eggs. Look for small, yellow, oblong eggs on the undersides of the leaves — I just wipe them off by hand.

I’ve also tried companion planting, like adding nasturtiums nearby. While this doesn’t completely prevent pests, it may help distract them. For a more hands-off approach, consistent covering is still the best option.

Harvesting Broccoli

You’ll know the broccoli head is ready when it’s firm and the buds are still tight. Don’t wait too long — once you see yellow flowers forming, it’s past its prime. In summer, broccoli heads can bolt quickly to flower while in the cooler months you have a bit more margin.

Even after the main head is harvested, don’t pull the plant. On many varieties, smaller side shoots will keep coming, especially in cooler weather.

FAQ How to Grow Broccoli

How long does broccoli take to grow?
Most broccoli varieties take between 60 to 100 days from seed to harvest. Growth time depends on the variety and your local climate.
Can I grow broccoli in containers?
Yes! Broccoli can be grown in large pots or containers. Make sure to use good organic soil and feed the plants with fertilizer. While the heads may be smaller than those grown in the ground, it’s a great option if you have limited space.
When is the best time to plant broccoli?
Broccoli grows best in cool seasons. Plant in early spring or autumn, depending on your climate. In frost-free areas, autumn to early spring works well.
How much space do broccoli plants need?
Space broccoli plants 45 cm (18 inches) apart to allow for airflow and healthy growth. This helps prevent fungal diseases and gives the leaves room to stretch.
How do I know when to harvest broccoli?
Harvest when the main head is tight, firm, and deep green, before the buds begin to flower.
How do I keep pests off broccoli plants?
Use garden netting or row covers to protect from cabbage moths. You can also handpick
Can I grow Microgreens with Broccoli seeds?
Yes, you can! Check out this post to find out how.

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